Which tool is needed. . . ?
TwoGuns
tools you want what tool would you choose? A metal lathe a metal mill
or some other?
DL
Jordan
A metal lathe a metal mill
> or some other?
>
> DL
It's hard to hold a job in the rotating spindle of a mill, but
relatively easy to mount a job on the saddle of a lathe, so lathe trumps
mill. In fact, a mill is a lathe, specialised for work with stationery
job and rotating cutter.
Jordan
Wes
sta...@prolynx.com
If you want to see how flexible a lathe can be, go look at back issues
of The Model Engineer. They had virtually nothing in the way of
modern machiine tools and came up with a lot of ways of doing with
what they had.
Stan
Gunner Asch
A mill.
"Aren't cats Libertarian? They just want to be left alone.
I think our dog is a Democrat, as he is always looking for a handout"
Unknown Usnet Poster
Heh, heh, I'm pretty sure my dog is a liberal - he has no balls.
Keyton
Steve W.
A good lathe.
It can be used for far more things than a mill.
--
Steve W.
Jim Wilkins
A horizontal boring machine with a spindle that accepts lathe chucks.
jsw
Michael Koblic
"TwoGuns" <R-D-L...@neb.rr.com> wrote in message
news:4a9ff5d1-b6a5-41e4...@p35g2000yqh.googlegroups.com...
> If you could only use one machine tool to make ALL or ANY machine
> tools you want what tool would you choose? A metal lathe a metal mill
> or some other?
>
FWIW even at my level I seem to use a small lathe about 8 times as often as
a small mill.
On a Desert Island I would have a lathe, The Godfather DVD and Dylan's
Highway 61 revisited...
--
Michael Koblic
Campbell River, BC
Rick Samuel
"TwoGuns" <R-D-L...@neb.rr.com> wrote in message
news:4a9ff5d1-b6a5-41e4...@p35g2000yqh.googlegroups.com...
A lathe can make another lathe, but a mill can not make another mill. No
CNC's allowed.
Jim Wilkins
wrote:
> "TwoGuns" <R-D-Lora...@neb.rr.com> wrote in message
> ...
> > If you could only use one machine tool to make ALL or ANY machine
> > tools you want what tool would you choose? A metal lathe a metal mill
> > or some other?
>
> > DL
>
> A lathe can make another lathe, but a mill can not make another mill. No
> CNC's allowed.
A lathe can make shafts, bearings and threads but a mill is much
better for machining ways, dovetails, etc. I've tried, it wasn't fun.
I picked the horizontal boring machine because it combines elements of
both, the spindle and tailstock of a lathe plus the XYZ axes of a
mill. If for some strange artificial reason I had to build one machine
to do everything it would resemble a horizontal boring mill with a
leadscrew added for threading, but it wouldn't be nearly as easy to
set up as separate turning and milling machines.
jsw
Gerald Miller
Some years back, I got playing around with me SB "A" and some CI
plate. After making a milling attachment, I made a duplicator for my
wood lathe, one piece of which is a piece with 14 flat sides.
Gerry :-)}
London, Canada
Jim Wilkins
> On Mon, 23 Nov 2009 03:57:55 -0800 (PST), Jim Wilkins
>
> Some years back, I got playing around with me SB "A" and some CI
> plate. After making a milling attachment, I made a duplicator for my
> wood lathe, one piece of which is a piece with 14 flat sides.
> Gerry :-)}
I made a lathe milling attachment, and then found a South Bend one.
Both work about equally poorly unless I take VERY light cuts. The
problem seems to be the inadequate clamps that hold the carriage down.
How did you index the 14 sided piece? A 14/28/56 tooth change gear?
jsw
Gerald Miller
It is a flat rectangle (6 surfaces) with two corners cut off to give
two more surfaces, then the perimeter is chamfered.
Top, bottom, six vertical faces and six bevels = 14
I clamped the piece to the milling attachment and used a fly cutter on
the spindle.
Gerry :-)}
London, Canada
RogerN
"Rick Samuel" <richard...@qatar.tamu.edu> wrote in message
news:hedmc4$d7d$1...@news.tamu.edu...
What part of a mill can't a mill make? How do you machine a lathe bed in a
lathe?
I think I'd prefer to use a mill to make 90% of either a lathe or a mill.
And for the other 10% I think it would be easier to make a spindle on a mill
than it would be to mill a cross slide table, but then again I've never seen
a very nice milling setup in a lathe.
RogerN
Jim Wilkins
>
> > A lathe can make another lathe, but a mill can not make another mill. No
> > CNC's allowed.
>
> What part of a mill can't a mill make? How do you machine a lathe bed in a
> lathe?
I think the idea is to remove the head and tailstock and use a tool
bit in the carriage to plane the ways. You might want to hang the new
lathe bed upside down over the old one so you can plane all the way
surfaces parallel.
When I needed to remachine a worn lathe bed I used a large horizontal
milling machine.
>
> I think I'd prefer to use a mill to make 90% of either a lathe or a mill.
> And for the other 10% I think it would be easier to make a spindle on a mill
> than it would be to mill a cross slide table, but then again I've never seen
> a very nice milling setup in a lathe.
>
> RogerN
You can mill cylindrical or conical surfaces on a rotary table or
between indexer centers. That's how I make tubing bender dies. I
suppose you could cut threads with a vee cutter or a fixed flycutter
bit by gearing the indexer to the table feed.
The American Precision Museum in Vermont has machine tools going back
to 1820 or so. By about 1860 practical experience had shaped them into
the forms we still have now. The smaller details such as quick-change
gearboxes and HSS tool bits were in place by 1900.
There are some versatile hybrids meant for moderate production runs
such as the Lincoln miller, which would be my model for a machine that
makes other machines.
http://www.sperdvac.org/Horizontal%20Mill/milling_machine_lincoln.jpg
I would make the tailstock support with two posts like the headstock
to better support it for tailstock drilling.
Scroll down to the bottom and look at "take-up" bearings:
http://www.baileynet.com/index.php?id=31&productcategory=1000011
jsw
Ed Huntress
"Jim Wilkins" <kb1...@gmail.com> wrote in message
news:057de754-0b57-4cfd...@t18g2000vbj.googlegroups.com...
On Nov 24, 1:24 am, "RogerN" <re...@midwest.net> wrote:
>
> > A lathe can make another lathe, but a mill can not make another mill. No
> > CNC's allowed.
>
> What part of a mill can't a mill make? How do you machine a lathe bed in a
> lathe?
>I think the idea is to remove the head and tailstock and use a tool
>bit in the carriage to plane the ways. You might want to hang the new
>lathe bed upside down over the old one so you can plane all the way
>surfaces parallel.
>
>When I needed to remachine a worn lathe bed I used a large horizontal
>milling machine.
I recall some drawings that I saw in the '70s, at _American Machinist_, that
illustrated the self-replicating nature of the lathe. It was a hypothetical
machine, with many components machined flat and/or bored on the faceplate
and with cylindrical ways, like a chucker (American Lathe?) that gained some
interest around 1978 - 1980 or so. There also were very small lathes,
typically types of specialized screw machines, made that way in the early
part of the last century.
Some of the very earliest screw-cutting lathes, maybe even Maudslay's
machine, had a V-way in front and a flat bedway in the back. The idea behind
that was that the V-way didn't require perfect straightness; slight
compensations could be made by filing or scraping the flat way to
compensate, effectively tilting the cross slide up or down a bit. It always
seemed to me that this would help only at one diameter of work, but that's
the way it was done, and many of them were made by hand before planers were
in common use for the purpose. The idea of the self-replicating lathe may
have included an assumption that some of the work was done by hand.
In any case, the running parts of a lathe depend upon round journals and
bushings, and most parts can be made that way either for running or for
locating, so the lathe was the most capable of self-replication.
--
Ed Huntress
Jim Wilkins
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
> Some of the very earliest screw-cutting lathes, maybe even Maudslay's
> machine, had a V-way in front and a flat bedway in the back. The idea behind
> that was that the V-way didn't require perfect straightness; slight
> compensations could be made by filing or scraping the flat way to
> compensate, effectively tilting the cross slide up or down a bit.
Are you sure? One vee way constrains its side of the carriage
horizontally and vertically, the other flat way allows the carriage to
center itself on the vee without over-constraining it. My South Bend
has two inverted vees for the carriage, which will wear out any slight
spacing error, and a vee plus a flat for the head and tailstocks which
won't.
> .... The idea of the self-replicating lathe may
> have included an assumption that some of the work was done by hand.
> Ed Huntress
What I've read in Holtzapffel et al suggests that the old lathe bed
was largely a reference for checking the new one as it was filed,
scraped and fitted by hand.
jsw
Ed Huntress
On Nov 24, 10:10 am, "Ed Huntress" <huntre...@optonline.net> wrote:
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
> ...
> Some of the very earliest screw-cutting lathes, maybe even Maudslay's
> machine, had a V-way in front and a flat bedway in the back. The idea
> behind
> that was that the V-way didn't require perfect straightness; slight
> compensations could be made by filing or scraping the flat way to
> compensate, effectively tilting the cross slide up or down a bit.
>Are you sure?
I'm sure that's the way many lathes were built, prior to the mid- or late
1800s. I'm not sure that the people explaining it got their explanation
right. I've always questioned it, but I never had a lot of literature to go
on.
>One vee way constrains its side of the carriage
>horizontally and vertically, the other flat way allows the carriage to
>center itself on the vee without over-constraining it.
Well, that's true, and the V-and-flat configuration has been used for the
simple reason that it requires little coordination between the location of
the two ways. That was always the way that I thought it was intended, from
the start. But a couple of sources that I used back when I was working on
the _AM_ 100th Anniversary Issue (1977) discussed the use of the flat way to
compensate for inaccuracies in the V-way.
It may be that one was just quoting the other unquestioningly. I suspect
that's the case, but I have no basis to question it except my own suspicion.
> My South Bend
>has two inverted vees for the carriage, which will wear out any slight
>spacing error, and a vee plus a flat for the head and tailstocks which
>won't.
Yeah. My South Bend, too. <g>
> .... The idea of the self-replicating lathe may
> have included an assumption that some of the work was done by hand.
> Ed Huntress
>What I've read in Holtzapffel et al suggests that the old lathe bed
>was largely a reference for checking the new one as it was filed,
>scraped and fitted by hand.
'Could be. I haven't read anything about it for decades, and there's been
quite a bit written about Maudslay's screw-cutting lathe. The trouble with
these informal histories is that they tend to use each other as sources,
which perpetuates a lot of wrong ideas.
--
Ed Huntress
Jim Wilkins
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
> 'Could be. I haven't read anything about it for decades, and there's been
> quite a bit written about Maudslay's screw-cutting lathe. The trouble with
> these informal histories is that they tend to use each other as sources,
> which perpetuates a lot of wrong ideas.
>
I just checked my two best sources, Holtzapffel #2 and Oscar Perrigo's
1916 "Lathe Design", Both skip quickly over the rationale for the
choice of flat vs vee lathe ways, and suggest that ease of production
was as much or more of a factor as sustained accuracy.
jsw
Ed Huntress
Well, yeah, we know that's why it was done later, after planers came into
widespread use. It's a lot easier to make three planes work together than
four.
And that may be (and I agree with your conclusion; it probably is) the
reason it was done from the very beginning.
As I think about this, I'm remembering what I thought about it at the time,
30 years ago. I believed then that the issue was the difficulty, without
planers, mills, or big surface grinders, of getting the four planes of a
pair of V-ways coordinated for straight and smooth travel. One way to
interpret this is that you can adjust the single plane of the flat way a lot
easier than the pair of planes you have with a second V. So to say that it
was simpler to correct accuracy with the V-and-flat could just mean that; if
the ways are hand-finished, you're correcting accuracy, and V-and-flat is a
lot easier to correct than two V's.
Maybe. <g>
--
Ed Huntress
Jim Wilkins
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
> ...
> ...
> As I think about this, I'm remembering what I thought about it at the time,
> 30 years ago. I believed then that the issue was the difficulty, without
> planers, mills, or big surface grinders, of getting the four planes of a
> pair of V-ways coordinated for straight and smooth travel. One way to
> interpret this is that you can adjust the single plane of the flat way a lot
> easier than the pair of planes you have with a second V. So to say that it
> was simpler to correct accuracy with the V-and-flat could just mean that; if
> the ways are hand-finished, you're correcting accuracy, and V-and-flat is a
> lot easier to correct than two V's.
>
> Maybe. <g>
>
> --
> Ed Huntress
If I read Holtzapffel correctly the two sides of inverted vee ways
were at first made separately, joined and aligned afterwards to fit
the fixed and moving poppit heads (headstock and tailstock to us).
"This slight width of base does not afford sufficient lateral support
to the heads, which with only moderate force in turning are liable to
vibration; while exact parallelism of the two angular edged bars is
also necessary. Improvement in stability was sought by making one side
of the bearers flat and broad, fig. 72, with a corresponding flat on
the underside of the lathe heads; retaining one angular side, to give
the direction or common axis. This arrangement also facilitated the
construction, as the parallelism of the two bars was no longer
essential,..."
Fig 72 shows one flat and one inverted vee way on a cast iron bed.
The difficulties of the early machine builders that Holtzapffel
recorded aren't that much different from those of a homebrew machine
tool maker today, except that we can buy ground drill rod and flat
stock and they could hire cheap child labor for tedious hand fitting.
jsw
Ed Huntress
Yeah. In the very beginning of modern lathes, the V-and-flat combinations
were assembled the same way. The first screw-cutting lathes had wood beds
with bolted-on iron ways, IIRC. (I'm doing this from memory; don't bite me.
<g>)
>"This slight width of base does not afford sufficient lateral support
>to the heads, which with only moderate force in turning are liable to
>vibration; while exact parallelism of the two angular edged bars is
>also necessary. Improvement in stability was sought by making one side
>of the bearers flat and broad, fig. 72, with a corresponding flat on
>the underside of the lathe heads; retaining one angular side, to give
>the direction or common axis. This arrangement also facilitated the
>construction, as the parallelism of the two bars was no longer
>essential,..."
Right. That sounds familiar.
>
>Fig 72 shows one flat and one inverted vee way on a cast iron bed.
>
>The difficulties of the early machine builders that Holtzapffel
>recorded aren't that much different from those of a homebrew machine
>tool maker today, except that we can buy ground drill rod and flat
>stock and they could hire cheap child labor for tedious hand fitting.
Right. Maybe you've peeked at my ideas for a ferrocement lathe with steel
ways. d8-)
(Having finished reading Naaman's _Ferrocement & Laminated Cementitious
Composites_, I'm less enthusiastic about that construction.)
--
Ed Huntress
Jim Wilkins
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
> ...
>
> ways. d8-)
>
> (Having finished reading Naaman's _Ferrocement & Laminated Cementitious
> Composites_, I'm less enthusiastic about that construction.)
Too late. There's one from ~1830? at the American Precision Museum
with wrought iron ways mortared into grooves in a granite base.
Another possibility is to make the ways rigid but not precise, like
spacers blocks between two channel irons, and use a bolt-on X-Y table
to control the tool. I would make the head and tailstock spindles a
standard drill rod size and use a separate piece of it to align the
head, tail and X-Y table axes after moving them.
jsw
Ed Huntress
On Nov 24, 2:03 pm, "Ed Huntress" <huntre...@optonline.net> wrote:
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
> ...
>
> Right. Maybe you've peeked at my ideas for a ferrocement lathe with steel
> ways. d8-)
>
> (Having finished reading Naaman's _Ferrocement & Laminated Cementitious
> Composites_, I'm less enthusiastic about that construction.)
> Ed Huntress-
>Too late. There's one from ~1830? at the American Precision Museum
>with wrought iron ways mortared into grooves in a granite base.
>
<g> Yes, there have been lots of concrete lathes, and stone-base lathes. I
ran a photo of one cast in reinforced concrete in _AM_ around 1978, made in
the USSR, that had a 65-foot-long bed.
My never-ending project is about a lathe for hobbyists. My original idea was
post-tensioned concrete. I may go back to that, based on some things I
learned about ferrocement. Or I may stick with the ferro and change a few
things to deal with issues. Post-tensioned concrete has its own issues.
Neither ferro nor post-tensioned answers all of the problems.
>Another possibility is to make the ways rigid but not precise, like
>spacers blocks between two channel irons, and use a bolt-on X-Y table
>to control the tool. I would make the head and tailstock spindles a
>standard drill rod size and use a separate piece of it to align the
>head, tail and X-Y table axes after moving them.
Good ideas. Lining things up is one of the issues, of course. Finish-honing
the headstock bearing retainers, using a simplified honing head (closer to a
lapping tool, actually) that runs on the lathe bedways, is a design I worked
on in the early '80s. I still think it would work OK.
--
Ed Huntress
Jim Wilkins
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
>
> Good ideas. Lining things up is one of the issues, of course. Finish-honing
> the headstock bearing retainers, using a simplified honing head (closer to a
> lapping tool, actually) that runs on the lathe bedways, is a design I worked
> on in the early '80s. I still think it would work OK.
>
> --
> Ed Huntress
I would try pillow blocks with setscrews or shaft clamps and jam two
of them together to get preloaded angular contact at the working end
of the spindle. Then the spindle (key-slotted shafting) could be
easily swapped so you could weld a plate on one to mount a chuck, for
instance.
jsw
Mark Rand
wrote:
>
>"Jim Wilkins" <kb1...@gmail.com> wrote in message
>news:01728995-32c7-4571...@1g2000vbm.googlegroups.com...
>On Nov 24, 11:00 am, "Ed Huntress" <huntre...@optonline.net> wrote:
>> "Jim Wilkins" <kb1...@gmail.com> wrote in message
>> ......
>> 'Could be. I haven't read anything about it for decades, and there's been
>> quite a bit written about Maudslay's screw-cutting lathe. The trouble with
>> these informal histories is that they tend to use each other as sources,
>> which perpetuates a lot of wrong ideas.
>>
>> Ed Huntress
>
>>I just checked my two best sources, Holtzapffel #2 and Oscar Perrigo's
>>1916 "Lathe Design", Both skip quickly over the rationale for the
>>choice of flat vs vee lathe ways, and suggest that ease of production
>>was as much or more of a factor as sustained accuracy.
>>
>>jsw
>
>Well, yeah, we know that's why it was done later, after planers came into
>widespread use. It's a lot easier to make three planes work together than
>four.
>
How the hell do you use rear tool posts or do heavy interrupted cuts with only
three or four guiding surfaces? (Hardinge Dovetail excepted, that works).
double V== six surfaces
Double box way== six surfaces
V-flat== five surfaces
Dovetail/flat== four surfaces
If the lathe does not have those numbers of guiding surfaces for the carriage,
then its design is dangerously compromised :-|
Grumble grumble grumble...
Mark Rand
RTFM
Jim Wilkins
> On Tue, 24 Nov 2009 13:04:07 -0500, "Ed Huntress" <huntre...@optonline.net>
> three or four guiding surfaces? (Hardinge Dovetail excepted, that works).
>
My South Bend, 44 years old this month, has a screwed-down plate under
the rear of the carriage that hooks over a ledge on the rear of the
ways. Perhaps it fit snugly all over once but now if it's a close fit
at the tailstock end there's a bit of play near the headstock. I just
checked and retightened it.
So I don't use a rear tool post and bandsaw the corners off plates
before turning disks. 3/8" and 1/2" tee slot studs work well to clamp
plates to the 4x6" bandsaw's base.
jsw
Ed Huntress
"Mark Rand" <ra...@internettie.co.uk> wrote in message
news:36nog5polg72ngao3...@4ax.com...
I'm not with you, Mark. Early lathes could not handle lifting forces on the
carriage, if that's what you're thinking. With a V-and-flat arrangement, the
X-axis location for the slide is the two sides of the V.
--
Ed Huntress
Ed Huntress
Interesting, but I think you'd have growth problems at the back end, unless
you made the spindle float in the inner race of the backside bearing -- or
had the backside bearings run right on the spindle, with clearance.
I'd use a tubular bearing holder (a piece of pipe) cast into a ferrocement
headstock, with floating rollers at the tail end and a pair of facing
tapered roller bearings on the head end. That's one traditional setup for
lathes, and it combines Z-axis stability, high load capacity, and
free-floating at the tail end to deal with Z-axis growth of the spindle.
I'd have to look at what kinds of bearings are cheaply available first.
--
Ed Huntress
Jim Wilkins
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
>
> you made the spindle float in the inner race of the backside bearing -- or
> had the backside bearings run right on the spindle, with clearance.
>
> I'd use a tubular bearing holder (a piece of pipe) cast into a ferrocement
> headstock, with floating rollers at the tail end and a pair of facing
> tapered roller bearings on the head end. That's one traditional setup for
> lathes, and it combines Z-axis stability, high load capacity, and
> free-floating at the tail end to deal with Z-axis growth of the spindle.
>
> I'd have to look at what kinds of bearings are cheaply available first.
So you have the drive pulley on the end of the spindle instead of
between the bearings? That does allow a higher reduction ratio, and
perhaps a crank handle for threading to a shoulder. Schedule 80 pipe
might have enough wall thickness to make a bearing seat and you could
clamp the bearings with bored-out pipe caps, as long as you can get
the pipe to run true both ways to make the seats parallel.
I would rather be able to adjust the spindle vertically for the Z axis
milling feed, or to turn an oversized pulley or bore a taper in the
spindle end.
I don't see the spindle heating and expanding enough to cause a
problem with the relatively light and flexible bearing support
framework of a homebrew machine.
jsw
Ed Huntress
On Nov 24, 6:42 pm, "Ed Huntress" <huntre...@optonline.net> wrote:
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
>
> Interesting, but I think you'd have growth problems at the back end,
> unless
> you made the spindle float in the inner race of the backside bearing -- or
> had the backside bearings run right on the spindle, with clearance.
>
> I'd use a tubular bearing holder (a piece of pipe) cast into a ferrocement
> headstock, with floating rollers at the tail end and a pair of facing
> tapered roller bearings on the head end. That's one traditional setup for
> lathes, and it combines Z-axis stability, high load capacity, and
> free-floating at the tail end to deal with Z-axis growth of the spindle.
>
> I'd have to look at what kinds of bearings are cheaply available first.
> Ed Huntress-
>So you have the drive pulley on the end of the spindle instead of
>between the bearings?
Yeah, I worked that out in one of my first sketches, and I saw no real
disadvantage. I was thinking about a pretty large (2 inch) hollow spindle.
In my original version, I didn't even have a drive or gears for threading.
It was going to use thread follower attachments, like the ones used on an
old Unimat or some screw machines.
The idea here was to build a little tank of a lathe with only the basics,
which you could build up as you go along. First you make a speed lathe;
learn some freehand turning and spin-forming; then add a tailstock; (do some
wood-turning); then a cross slide (using it like a gang-turn Wasino), and
eventually, a compound. You could add a power Z-axis feedscrew and my
thought at the time (around 1980) was that CNC was going to become cheap
enough that you might never have geared thread-cutting at all, going
straight to servos for CNC threading.
The reason for the ferrocement over other kinds of reinforced concrete was
twofold. First, it allows free-form shapes, so you could make the headstock
a hollow monocoque type, like modern lathes, rather than deal with the lack
of lateral (X-axis) flexibility of old designs with pillow-block or
stantion-type bearing supports. The structure of the bed would be a torque
box, rather than parallel beams. That would give you rigidity throughout,
without adding a lot of mass.
The second reason is that it's isotropic; you don't have to engineer around
the lines of tensile stress that can be tolerated. It's more like a metal
than reinforced concrete in its mechanical properties. That's easier for us
amateurs.
It wasn't really a conventional design but it combined separate elements of
well-tried lathe types. I had some suppositions about the ability of
ferrocement to handle tensile loads which I've since learned, after reading
Naaman's book, are not exactly true. (It will handle the loads, but it will
microcrack under tension).
But ferrocement still has some big advantages over other kinds of
reinforcement. It still could be the best choice, perhaps with a bit of
hybridization, using post-tensioned tendons at the bottoms of the lathe bed,
or maybe some fibers to prevent microcracks. 'Dunno. If I get some time,
I'll have to re-think it now that I have the engineering data to help me
along.
>That does allow a higher reduction ratio, and
>perhaps a crank handle for threading to a shoulder. Schedule 80 pipe
>might have enough wall thickness to make a bearing seat and you could
>clamp the bearings with bored-out pipe caps, as long as you can get
>the pipe to run true both ways to make the seats parallel.
The idea here was to turn a piece of tubing of some sort to all of the
inside and outside dimensions, including threading for the bearing
retainers, to within a couple of thousandths. One hopes that you have a
friend with a lathe. <g> Or, if it was a club-type project, these parts
could be made and sold.
Then make a rig that fits tightly into the bore and which has three pads
that rest on the bedways to align the spindle-holding tube close enough
while the structure is curing that you could hone the tube bore to final
dimensions, without a lot of wasted effort.
>I would rather be able to adjust the spindle vertically for the Z axis
>milling feed, or to turn an oversized pulley or bore a taper in the
>spindle end.
OK, there's a lot of room for variation in the basic idea.
>
>I don't see the spindle heating and expanding enough to cause a
>problem with the relatively light and flexible bearing support
>framework of a homebrew machine.
In good lathe designs, I believe you'll find that the typical setup is to
have a pair of preloaded bearings facing each other at the spindle-nose end.
In classic designs, these were angular tapered-roller bearings in larger
lathes, and angular-contact ball bearings in smaller ones. All of your
Z-axis location is accomplished with these head-end bearings. Then the tail
end of the spindle was held in a single- or double-row bearing that allowed
linear movement -- either straight rollers, or ball bearings that allow the
spindle to move.
It doesn't take much heat to make the spindle grow substantially, which will
either overload your bearings or unload the preload on the head-end
bearings. Also, this lathe is no wimp. It would handle much higher loads
than my SB-10L and would be roughly the same size, although a little wider
and probably a little shorter (mine has the 54" bed).
Anyway, it's been a good thought exercise for me from time to time. My ideas
about it have changed a bit, but, basically, the objective is to design a
lathe that a determined amateur with no experience could build at home. Some
parts are tricky and will require machining; I've never worked out a really
good saddle, cross-slide, and compound that can be made easily at home.
As I said, I see it as a progressive design. You could start using it as
soon as you complete the basic steps, learning and gaining some experience
while making some fun and useful things, and then build it up in stages to a
full-blown thread-cutting engine lathe. With CNC threading, no less. <g>
I would love to see someone with more time and the ambition for it take some
of these thoughts and carry it through. I've been diddling with it for so
long that I'm losing heart to do it.
--
Ed Huntress
Gunner Asch
<ra...@internettie.co.uk> wrote:
>(Hardinge Dovetail excepted, that works)
Indeed it does...and its actually 3 surfaces..or 5 if you are counting
Gunner
Jim Wilkins
I used different design criteria, this machine would take on
occasional jobs too large for my lathe and mill. That means it can be
built lighter and cheaper than normal and only have to take finishing
cuts on pieces roughed out with a saw or cutting torch.
(pause to watch Mya dance)
As a bootstrap machine it could make parts to upgrade itself.
The other similar project is a Harig-style cylindrical and tool
grinding attachment for my Toolmaker surface grinder, to make it more
like a Quorn.
This would resemble a small and precise lathe headstock and spindle
that includes sliding motion. The 5C spindle of a spin index might be
a decent start if it can be cleaned up well enough and converted to an
air bearing. The grinder has a Y leadscrew so the Quorn's complexity
can be reduced.
I bought a Morse taper adapter with the outside ground to 1.000 OD for
this project and discovered that it had bulged slightly around the
release key slot.
jsw
Ed Huntress
Those sound like good projects, too. Regarding the big machine, things like
gap-bed lathes with big swings are a natural for the ferrocement
construction method. You can span long distances at very low cost. It's also
a good place for cylindrical bedways. The travels typically are short, and
you have plenty of room to make their diameter as large as you need.
In fact, a big gap-bed lathe with short tool travels would be easier than a
thread-cutting engine lathe by a wide margin. If you have to face big disks,
however, the whole prospect is a lot more difficult.
--
Ed Huntress
Ned Simmons
<hunt...@optonline.net> wrote:
>
>In good lathe designs, I believe you'll find that the typical setup is to
>have a pair of preloaded bearings facing each other at the spindle-nose end.
>In classic designs, these were angular tapered-roller bearings in larger
>lathes, and angular-contact ball bearings in smaller ones. All of your
>Z-axis location is accomplished with these head-end bearings. Then the tail
>end of the spindle was held in a single- or double-row bearing that allowed
>linear movement -- either straight rollers, or ball bearings that allow the
>spindle to move.
>
>It doesn't take much heat to make the spindle grow substantially, which will
>either overload your bearings or unload the preload on the head-end
>bearings. Also, this lathe is no wimp. It would handle much higher loads
>than my SB-10L and would be roughly the same size, although a little wider
>and probably a little shorter (mine has the 54" bed).
Hardinge uses a single pair of angular contact bearings, one bearing
at either end of the spindle, in the HLVH headstock -- a 3000RPM
spindle with 25 millionths runout. The preload is controlled by a pair
of spacers that introduce an offset between the inner and outer races.
The drive belt is outboard of the rear bearing.
One problem with tapered roller bearings, depending on how fussy you
are, is that the runout specs on standard bearings is pretty bad
compared to run of the mill ball bearings. And precision grade roller
bearings are horribly expensive and can be difficult to source.
--
Ned Simmons
Ed Huntress
"Ned Simmons" <ne...@nedsim.com> wrote in message
news:jsbpg5dl688ih8btk...@4ax.com...
> On Tue, 24 Nov 2009 20:38:12 -0500, "Ed Huntress"
> <hunt...@optonline.net> wrote:
>
>>
>>In good lathe designs, I believe you'll find that the typical setup is to
>>have a pair of preloaded bearings facing each other at the spindle-nose
>>end.
>>In classic designs, these were angular tapered-roller bearings in larger
>>lathes, and angular-contact ball bearings in smaller ones. All of your
>>Z-axis location is accomplished with these head-end bearings. Then the
>>tail
>>end of the spindle was held in a single- or double-row bearing that
>>allowed
>>linear movement -- either straight rollers, or ball bearings that allow
>>the
>>spindle to move.
>>
>>It doesn't take much heat to make the spindle grow substantially, which
>>will
>>either overload your bearings or unload the preload on the head-end
>>bearings. Also, this lathe is no wimp. It would handle much higher loads
>>than my SB-10L and would be roughly the same size, although a little wider
>>and probably a little shorter (mine has the 54" bed).
>
> Hardinge uses a single pair of angular contact bearings, one bearing
> at either end of the spindle, in the HLVH headstock -- a 3000RPM
> spindle with 25 millionths runout.
Hmm. Is that right? I thought Hardinges had the classic two-bearing-front,
floating rear setup. But I don't know for sure. Maybe Gunner would know.
In any case, they use Class 9 bearings in their top-of-the-line, and those
spindles run exceptionally cool. They aren't a good example to follow for
any ordinary lathe. You'd never be able to duplicate the performance of that
spindle.
Ned Simmons
<hunt...@optonline.net> wrote:
It's as I've described. I've been in there and have a picture here in
front of me.
>
>In any case, they use Class 9 bearings in their top-of-the-line, and those
>spindles run exceptionally cool. They aren't a good example to follow for
>any ordinary lathe. You'd never be able to duplicate the performance of that
>spindle.
The key to controlling the temperature rise is more closely related to
accurately setting the preload than the bearing class. In order to get
reasonable stiffness you'd probably not want to mount the nose
bearings directly back to back, and the most practical way to get the
required separation is with a pair of spacers. The length of those
spacers is critical to setting the preload, regardless of how long
they are.
I've designed quite a few spindles, and I think temperature effects
are way down on the list of things to worry about when thinking about
buliding a ball bearing headstock on the cheap with limited equipment.
>
>> The preload is controlled by a pair
>> of spacers that introduce an offset between the inner and outer races.
>> The drive belt is outboard of the rear bearing.
>>
>> One problem with tapered roller bearings, depending on how fussy you
>> are, is that the runout specs on standard bearings is pretty bad
>> compared to run of the mill ball bearings. And precision grade roller
>> bearings are horribly expensive and can be difficult to source.
>>
>> --
>> Ned Simmons
>
--
Ned Simmons
Ed Huntress
Ok, then maybe it's just the HLVH? Because I used a cutaway drawing of a
Hardinge spindle once to illustrate exactly what we've been talking about
here, and, although I don't remember the drawing perfectly, I do remember
what I wrote for the caption. Are you familiar with the earlier Hardinges?
>
>>
>>In any case, they use Class 9 bearings in their top-of-the-line, and those
>>spindles run exceptionally cool. They aren't a good example to follow for
>>any ordinary lathe. You'd never be able to duplicate the performance of
>>that
>>spindle.
>
> The key to controlling the temperature rise is more closely related to
> accurately setting the preload than the bearing class. In order to get
> reasonable stiffness you'd probably not want to mount the nose
> bearings directly back to back, and the most practical way to get the
> required separation is with a pair of spacers. The length of those
> spacers is critical to setting the preload, regardless of how long
> they are.
>
> I've designed quite a few spindles, and I think temperature effects
> are way down on the list of things to worry about when thinking about
> buliding a ball bearing headstock on the cheap with limited equipment.
Aha. Are you saying you'd run opposed, preloaded bearings at opposite ends
of the spindle on a lathe like we've described here? Because I was once
pretty familiar with bearing layouts in machine tools, and it just goes
against everything I was taught. I'm not saying you're wrong, but there is a
pretty fair amount of work behind the things I thought I learned when I was
writing about it. If it's all wrong, I have some work to do here in a hurry.
Gunner Asch
wrote:
They can be..yes.
Good post btw.
Gunner
Gunner Asch
wrote:
>
>>Hmm. Is that right? I thought Hardinges had the classic two-bearing-front,
>>floating rear setup. But I don't know for sure. Maybe Gunner would know.
>
>It's as I've described. I've been in there and have a picture here in
>front of me.
Very early Hardinges had the 2 bearing front..1940s-early 50s
vintage..but since the late 50s..all have been as Ned said.
Thats for manual and microswitch automatics.
Gunner
Mark Rand
wrote:
Oops. Miscounted there. I don't know where the extra one crept in from...
Very definitely only three guiding surfaces on the dovetail beds of the
Brothers Hardinge.
Regards
Mark Rand
RTFM
Gunner Asch
<ra...@internettie.co.uk> wrote:
>On Tue, 24 Nov 2009 19:09:44 -0800, Gunner Asch <gun...@NOSPAMlightspeed.net>
>wrote:
>
>>On Tue, 24 Nov 2009 22:46:10 +0000, Mark Rand
>><ra...@internettie.co.uk> wrote:
>>
>>>(Hardinge Dovetail excepted, that works)
>>
>>
>>Indeed it does...and its actually 3 surfaces..or 5 if you are counting
>>
>>
>>Gunner
>
>
>Oops. Miscounted there. I don't know where the extra one crept in from...
>
>Very definitely only three guiding surfaces on the dovetail beds of the
>Brothers Hardinge.
>
>Regards
>Mark Rand
>RTFM
<G>
Gunner
Jim Wilkins
> On Tue, 24 Nov 2009 20:38:12 -0500, "Ed Huntress"
>
> One problem with tapered roller bearings, depending on how fussy you
> are, is that the runout specs on standard bearings is pretty bad
> compared to run of the mill ball bearings. And precision grade roller
> bearings are horribly expensive and can be difficult to source.
>
Does bearing runout matter as much if you finish the spindle nose -
after- keying and clamping it in place?
For my version you swap spindles rather than making precise threads
and tapers on the nose, so keying or at least putting the clamp
setscrews back in the same depressions is important.
jsw
Denis G.
> On Nov 24, 1:24 am, "RogerN" <re...@midwest.net> wrote:
>
>
>
> > > A lathe can make another lathe, but a mill can not make another mill. No
> > > CNC's allowed.
>
> > What part of a mill can't a mill make? How do you machine a lathe bed in a
> > lathe?
>
> I think the idea is to remove the head and tailstock and use a tool
> bit in the carriage to plane the ways. You might want to hang the new
> lathe bed upside down over the old one so you can plane all the way
> surfaces parallel.
>
> When I needed to remachine a worn lathe bed I used a large horizontal
> milling machine.
>
>
>
> > I think I'd prefer to use a mill to make 90% of either a lathe or a mill.
> > And for the other 10% I think it would be easier to make a spindle on a mill
> > than it would be to mill a cross slide table, but then again I've never seen
> > a very nice milling setup in a lathe.
>
> > RogerN
>
> You can mill cylindrical or conical surfaces on a rotary table or
> between indexer centers. That's how I make tubing bender dies. I
> suppose you could cut threads with a vee cutter or a fixed flycutter
> bit by gearing the indexer to the table feed.
>
> The American Precision Museum in Vermont has machine tools going back
> to 1820 or so. By about 1860 practical experience had shaped them into
> the forms we still have now. The smaller details such as quick-change
> gearboxes and HSS tool bits were in place by 1900.
>
> There are some versatile hybrids meant for moderate production runs
> such as the Lincoln miller, which would be my model for a machine that
> makes other machines.http://www.sperdvac.org/Horizontal%20Mill/milling_machine_lincoln.jpg
>
> I would make the tailstock support with two posts like the headstock
> to better support it for tailstock drilling.
>
> Scroll down to the bottom and look at "take-up" bearings:http://www.baileynet.com/index.php?id=31&productcategory=1000011
>
> jsw
The picture of the "Lincoln miller" seems to have a "Pratt & Whitney"
logo on the bed.
Joseph Gwinn
"Ed Huntress" <hunt...@optonline.net> wrote:
Significant work has been done on concrete-filled fabricated metal
frames for precision machine tools.
The place to start is MIT professor Alexander H. Slocum
(http://meche.mit.edu:16080/people/index.html?id=80). A good discussion
and many references may be found in his book "Precision Machine Design".
Joe Gwinn
Jim Wilkins
> On Nov 24, 8:04 am, Jim Wilkins <kb1...@gmail.com> wrote:
> > Scroll down to the bottom and look at "take-up" bearings:http://www.baileynet.com/index.php?id=31&productcategory=1000011
>
> > jsw
>
> The picture of the "Lincoln miller" seems to have a "Pratt & Whitney"
Here's a little of the interrelationship between the machine builders
of Hartford, which somewhat like Maudslay's group in England:
http://www.hogriver.org/issues/v02n03/miracle.htm
jsw
Ed Huntress
"Joseph Gwinn" <joeg...@comcast.net> wrote in message
news:joegwinn-A7AA94...@news.giganews.com...
Thanks, Joe. I talked to Slocum not too long ago -- maybe a year or two --
and someone here brought up his book before (maybe you?) -- it's on my list
of things to get for my library. I had a copy for a couple of weeks on an
interlibrary loan, and I read what he had to say about long-term stability
and so on, which helped a lot.
I should point out that I was studying and writing about concrete- and
polymer/aggregate-base machines around 30 years ago, and I've visited
manufacturers of them in the US and in France and Italy, mostly around that
time but as recently as seven years ago. I'm familiar in general with the
various approaches, the materials, and the design philosophies. But I've
never claimed expertise; it was more on the level of a good journalistic
exercise.
The commercial applications are one thing. This wild hair I've been chasing
has more to do with exploring strategies for building at home, at very low
cost, and to see what can be done with a material that's intrigued me for 40
years -- ferrocement. The obvious approach to building a machine like this
would be either a fairly massive, fiber-filled casting or a screw-tensioned,
post-tensioned cast structure. The former is my next area of study and it's
a big one. The latter is something I've abandoned because of problems with
long-term stability and engineering that's trickier than it looks. But it
would be a great way to go, if it wasn't for the stability issue.
I'm convinced that a concrete machine can deliver ordinary lathe accuracy
and could be perfectly suitable for the hobbyist. Problems crop up when you
go for high-end, toolroom-grade accuracy and long-term stability. The
polymers are better for that but they're *very* expensive, and defeat the
basic goals I'm starting with.
Anyway, thanks for the tip. I would love to go for this in a big way, but it
isn't in the cards right now. I'm engaged in conversation with Dr. Senft on
Stirling engine lubrication, and the outcome is going to eat me up for
months to come. d8-)
BTW, if anyone is interested in the approach you mention, which is various
forms of making a light welded or bolted steel structure and filling it with
concrete, it has possibilities for the home builder. But it's a lot trickier
than you might think. There are bonding issues and problems with the
different coefficients of expansion between steel and various...er,
"fillings," plus retained-stress issues with the steel itself. And concrete
grows (or shrinks; I forget) for decades after it's cast. It's not enough to
matter in building structures but it can be an issue when you're dealing
with thousandths of an inch.
--
Ed Huntress
Ed Huntress
"Gunner Asch" <gun...@NOSPAMlightspeed.net> wrote in message
news:13spg5hehm7ahv398...@4ax.com...
Thanks, Gunner. It's not that I don't believe Ned, it's just that I *know*
I've seen that two-bearing arrangement on drawings of Hardinge spindles. I
guess it was just the old ones.
Now Ned has me going. <g> I'm not going to be happy until I figure out what
they're doing with a spindle that contains preloaded bearings at each end.
Something is unusual here. I just called Hardinge; all of my old contacts
are either dead or retired. d8-( (Hardinge was once my client.) The
service desk doesn't even know of anyone on their staff who would know about
them anymore.
<sigh> Another question that will have to go to the end of a long line...
--
Ed Huntress
Jim Wilkins
> ...And concrete
> grows (or shrinks; I forget) for decades after it's cast. It's not enough to
> matter in building structures but it can be an issue when you're dealing
> with thousandths of an inch.
I wonder if you could get around that by decoupling the ways from the
frame, perhaps mount them between clamping cap screws and supporting
setscrews and realign them to a straightedge before a critical job. It
would be like spotting and scraping, but quicker.
I've built a few instruments using that principle and found I could
hit micron accuracy as long as the screw seating surfaces were smooth
and lubricated and I left room for a wrench on both the pushing and
pulling screws at the same time, so I could slowly increase the torque
on both as the position readout approached zero.
My proof-of-concept demo to get permission was adjusting a 4-jaw lathe
chuck to within a micron. They brought me in as the electronic tech
and I had to prove that I could do the mechanical design and
construction of the lab prototypes as well.
jsw
Joseph Gwinn
"Ed Huntress" <hunt...@optonline.net> wrote:
Very likely. I recall posting the reference before. Yes. The thread
was "Epoxy grainite build yer own machine frame" in March 2009.
> -- it's on my list
> of things to get for my library. I had a copy for a couple of weeks on an
> interlibrary loan, and I read what he had to say about long-term stability
> and so on, which helped a lot.
I bet you can borrow it again.
> I should point out that I was studying and writing about concrete- and
> polymer/aggregate-base machines around 30 years ago, and I've visited
> manufacturers of them in the US and in France and Italy, mostly around that
> time but as recently as seven years ago. I'm familiar in general with the
> various approaches, the materials, and the design philosophies. But I've
> never claimed expertise; it was more on the level of a good journalistic
> exercise.
>
> The commercial applications are one thing. This wild hair I've been chasing
> has more to do with exploring strategies for building at home, at very low
> cost, and to see what can be done with a material that's intrigued me for 40
> years -- ferrocement. The obvious approach to building a machine like this
> would be either a fairly massive, fiber-filled casting or a screw-tensioned,
> post-tensioned cast structure. The former is my next area of study and it's
> a big one. The latter is something I've abandoned because of problems with
> long-term stability and engineering that's trickier than it looks. But it
> would be a great way to go, if it wasn't for the stability issue.
Slocum runs hot and cold about concrete versus lots of cast iron, but he
isn't trying for infinite life either.
If it's cheap enough, people will live with something that doesn't last
100 years. Most HSMers won't last that long.
> I'm convinced that a concrete machine can deliver ordinary lathe accuracy
> and could be perfectly suitable for the hobbyist. Problems crop up when you
> go for high-end, toolroom-grade accuracy and long-term stability. The
> polymers are better for that but they're *very* expensive, and defeat the
> basic goals I'm starting with.
>
> Anyway, thanks for the tip. I would love to go for this in a big way, but it
> isn't in the cards right now. I'm engaged in conversation with Dr. Senft on
> Stirling engine lubrication, and the outcome is going to eat me up for
> months to come. d8-)
Is there a good solution? I recall that this was one of the big issues.
> BTW, if anyone is interested in the approach you mention, which is various
> forms of making a light welded or bolted steel structure and filling it with
> concrete, it has possibilities for the home builder. But it's a lot trickier
> than you might think. There are bonding issues and problems with the
> different coefficients of expansion between steel and various...er,
> "fillings," plus retained-stress issues with the steel itself. And concrete
> grows (or shrinks; I forget) for decades after it's cast. It's not enough to
> matter in building structures but it can be an issue when you're dealing
> with thousandths of an inch.
Yes. Slocum goes over this.
The issue is to replicate the static and dynamic stiffness of cast iron
more cheaply (or with less weight) than cast iron.
A fabricated box-beam frame has plenty of static stiffness, but has far
too little damping, so the dynamic stiffness is scant. Filling the
frame is an attempt to sharply increase the damping and thus dynamic
stiffness, to make the chatter threshold more remote.
Joe Gwinn
Ed Huntress
I can, but I'd like to have it. It ain't cheap, and my list of desired books
is long.
Right. <g> I don't think that the limitation is the life of the machine, but
rather of dealing with growth or shrinkage over a period of years. There are
ways around it. I just haven't thought it through. But, again, we're talking
about the difference between, say, a South Bend and a Hardinge. You can
build something that will fit into the SB category. But concrete is not the
stuff to use if you want Hardinge.
Then again, if you want Hardinge, you'd better mortgage the house and buy
Hardinge. <g> I own a South Bend, and it's all I could want for my hobby
machining.
>
>
>> I'm convinced that a concrete machine can deliver ordinary lathe accuracy
>> and could be perfectly suitable for the hobbyist. Problems crop up when
>> you
>> go for high-end, toolroom-grade accuracy and long-term stability. The
>> polymers are better for that but they're *very* expensive, and defeat the
>> basic goals I'm starting with.
>>
>> Anyway, thanks for the tip. I would love to go for this in a big way, but
>> it
>> isn't in the cards right now. I'm engaged in conversation with Dr. Senft
>> on
>> Stirling engine lubrication, and the outcome is going to eat me up for
>> months to come. d8-)
>
> Is there a good solution? I recall that this was one of the big issues.
You'll have to read my article, should I succeed in gathering enough info to
write one. There are solutions that work; different solutions for different
realms, from low-temperature-differential types to fractional-horsepower
mule motors, up to 100-hp-plus automotive engines. The solutions are all
different. Senft has put me on to a guy who apparently is one of the world's
experts on automotive Stirlings, and who knows the big-time lubrication
solutions, both for kinematic engines and for free-piston types. I haven't
talked to him yet. I'm looking forward to doing so.
>
>
>> BTW, if anyone is interested in the approach you mention, which is
>> various
>> forms of making a light welded or bolted steel structure and filling it
>> with
>> concrete, it has possibilities for the home builder. But it's a lot
>> trickier
>> than you might think. There are bonding issues and problems with the
>> different coefficients of expansion between steel and various...er,
>> "fillings," plus retained-stress issues with the steel itself. And
>> concrete
>> grows (or shrinks; I forget) for decades after it's cast. It's not enough
>> to
>> matter in building structures but it can be an issue when you're dealing
>> with thousandths of an inch.
>
> Yes. Slocum goes over this.
>
> The issue is to replicate the static and dynamic stiffness of cast iron
> more cheaply (or with less weight) than cast iron.
>
> A fabricated box-beam frame has plenty of static stiffness, but has far
> too little damping, so the dynamic stiffness is scant. Filling the
> frame is an attempt to sharply increase the damping and thus dynamic
> stiffness, to make the chatter threshold more remote.
>
> Joe Gwinn
Yes. But a torsion box (box-beam) made of concrete has lots of natural
damping. As you say, the filled-base commercial machines have been attempts
to build in damping with low shipping weight (and lower costs) for the
machines.
It's a very tricky engineering problem, but it doesn't require a lot of
knowledge or heavy math. It just requires a good feel for materials and
structures, combined with a lot of patient thought and analysis.
--
Ed Huntress
Denis G.
Thanks for that interesting bit of history. I'll have to read more
when I get the time. I didn't realise that Hartford could have become
the "Motor City" and had important rivals to Henry Ford and his
ventures.
Ned Simmons
<hunt...@optonline.net> wrote:
>
>Aha. Are you saying you'd run opposed, preloaded bearings at opposite ends
>of the spindle on a lathe like we've described here? Because I was once
>pretty familiar with bearing layouts in machine tools, and it just goes
>against everything I was taught. I'm not saying you're wrong, but there is a
>pretty fair amount of work behind the things I thought I learned when I was
>writing about it. If it's all wrong, I have some work to do here in a hurry.
I'm not saying what I would do, but what I *wouldn't* do right off the
bat is rule out the HLVH arrangement without taking into account how
much simpler it is to build. Using a pair of identical bearings at
either end of the spindle eliminates the need for a stepped bore with
an accurate shoulder to retain a paired bearing at the nose. The
bearings can mount in a straight bore with a separate cap at each end.
The spindle itself is also simpler without the need for different
diameter bearing seats and locknut threads at both ends, which in turn
force the nose bearings to get larger for a given spindle ID. The
larger bearings are necessary to clear the threads and seat at the
tail end at assembly.
But I assume Hardinge uses the two-bearing arrangement not so much
because it's cheaper and easier, but because eliminating all the fussy
features required for a more rigid arrangement makes it practical to
build an exceptionally accurate headstock. In other words, when
building a spindle on the cheap, one might end up with a similar
design, but for different reasons.
Another thing to consider is that the paired bearing at the nose
arrangement is prevalent in gear head lathes where the drive and
connection to the threading gearbox is in the middle of the headstock,
between the bearings. The HLVH, doesn't have to deal with this
complexity, and neither does your concept, if I have a proper picture
of it.
If rigidity is paramount, some of the problems with stepped bores and
shafts can be helped with a few neat products made by these folks:
http://www.meibuhr.com/
Over the years I've gleaned some knowledge and ideas form RT Gilman's
literature, though it looks as though they don't show as much detail
on the internal construction of their spindles as they once did.
http://www.skfpt.com/spindles.html
The New Departure Handbook is also an excellent basic and accessible
reference.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=390030014670
--
Ned Simmons
Ned Simmons
Probably not as much, but keep in mind that a ball or roller bearing
is not in the same configuration on every revolution -- there's
relative motion between the races and the balls (rollers) such that
the balls (rollers) orbit at a different rate than the rotating race.
Consequently, my understanding is that if you monitor runout with
enough resolution you'll see a component of the runout that's not in
synch with the RPM of the race. As a practical matter, for a
home-built spindle, I wouldn't worry about the effect with normal deep
row ball bearings. In the case of tapered rollers I don't have a good
SWAG one way or the other without doing more research.
--
Ned Simmons
Joseph Gwinn
"Ed Huntress" <hunt...@optonline.net> wrote:
> "Gunner Asch" <gun...@NOSPAMlightspeed.net> wrote in message
> news:13spg5hehm7ahv398...@4ax.com...
> > On Wed, 25 Nov 2009 00:47:42 -0500, Ned Simmons <ne...@nedsim.com>
> > wrote:
> >
> >>
> >>>Hmm. Is that right? I thought Hardinges had the classic
> >>>two-bearing-front,
> >>>floating rear setup. But I don't know for sure. Maybe Gunner would know.
> >>
> >>It's as I've described. I've been in there and have a picture here in
> >>front of me.
> >
> >
> > Very early Hardinges had the 2 bearing front..1940s-early 50s
> > vintage..but since the late 50s..all have been as Ned said.
> >
> > Thats for manual and microswitch automatics.
> >
> > Gunner
>
> Thanks, Gunner. It's not that I don't believe Ned, it's just that I *know*
> I've seen that two-bearing arrangement on drawings of Hardinge spindles. I
> guess it was just the old ones.
>
> Now Ned has me going. <g> I'm not going to be happy until I figure out what
> they're doing with a spindle that contains preloaded bearings at each end.
> Something is unusual here. I just called Hardinge; all of my old contacts
> are either dead or retired. d8-( (Hardinge was once my client.)
Google on their names? Perhaps they are alive, but bored, and need to
find RCM.
Joe Gwinn
Joseph Gwinn
Ned Simmons <ne...@nedsim.com> wrote:
You got me curious, so I did some searching. A good source of the how
and why of spindle designs is the patent literature.
A search on SKF yielded 5,636,950.
A more general search yielded 6,158,895 (and the similar 6,293,703) and
4,226,485 (which is referenced by 5,739,607 and 4,611,934).
The above patents are the ones with good explanations. Patents may be
downloaded from Google Patents and www.pat2pdf.net.
Joe Gwinn
Jim Wilkins
> On Wed, 25 Nov 2009 04:18:14 -0800 (PST), Jim Wilkins
> Consequently, my understanding is that if you monitor runout with
> enough resolution you'll see a component of the runout that's not in
> synch with the RPM of the race. As a practical matter, for a
> home-built spindle, I wouldn't worry about the effect with normal deep
> row ball bearings. In the case of tapered rollers I don't have a good
> SWAG one way or the other without doing more research.
>
My tentative plan for best accuracy is to cut center points on the
head and tail spindles and run them live until the work is almost to
size, then lock them down and make the final parallelism, size and
surface finish cuts between dead centers, driving the work directly
with a belt or rubber idler. I expect that the unhardened centers
might have to be refinished afterwards.
This applies more to the cylindrical grinding fixture than a homebrew
lathe, since I found an old South Bend headstock with the same spindle
thread as my lathe's to use for a temporary oversized wheel lathe.
jsw
Joseph Gwinn
"Ed Huntress" <hunt...@optonline.net> wrote:
I've been tempted as well.
I've been tempted as well. But I like my house, so Clausing will have
to carry on.
> >> I'm convinced that a concrete machine can deliver ordinary lathe accuracy
> >> and could be perfectly suitable for the hobbyist. Problems crop up when
> >> you
> >> go for high-end, toolroom-grade accuracy and long-term stability. The
> >> polymers are better for that but they're *very* expensive, and defeat the
> >> basic goals I'm starting with.
> >>
> >> Anyway, thanks for the tip. I would love to go for this in a big way, but
> >> it
> >> isn't in the cards right now. I'm engaged in conversation with Dr. Senft
> >> on
> >> Stirling engine lubrication, and the outcome is going to eat me up for
> >> months to come. d8-)
> >
> > Is there a good solution? I recall that this was one of the big issues.
>
> You'll have to read my article, should I succeed in gathering enough info to
> write one. There are solutions that work; different solutions for different
> realms, from low-temperature-differential types to fractional-horsepower
> mule motors, up to 100-hp-plus automotive engines. The solutions are all
> different. Senft has put me on to a guy who apparently is one of the world's
> experts on automotive Stirlings, and who knows the big-time lubrication
> solutions, both for kinematic engines and for free-piston types. I haven't
> talked to him yet. I'm looking forward to doing so.
Please keep us posted. It's even on topic, too.
As I said, Slocum runs hot and cold on this in the book. The savings
were not dramatic, even if he used aluminum weldments for the machine
frame. (Yes, it's a torsion box, bent into a C-form.) I think Slocum
did build such machines, so the tradeoff summary wasn't just a
theoretical musing.
Slocum patented (5,799,924 and 5,743,326) a vibration damper consisting
of a tube with a greased steel rod within, with the space between tube
and greased rod filled with poured-in epoxy resin. The grease acts as a
mold release, so the rod is floating, and later acts as the goop layer
to absorb vibration. I think that this was intended for boring bars, as
an alternative to solid carbide. And one could make the tube from solid
carbide as well.
I suppose one could embed a greased inner box frame inside the box beam
machine frame before filling with resin. From his patent drawings,
Slocum is thinking this way.
Joe Gwinn
Gunner Asch
wrote:
>http://www.hogriver.org/issues/v02n03/miracle.htm
Way cool! Thanks!
Gunner
"Aren't cats Libertarian? They just want to be left alone.
I think our dog is a Democrat, as he is always looking for a handout"
Unknown Usnet Poster
Heh, heh, I'm pretty sure my dog is a liberal - he has no balls.
Keyton
Ed Huntress
Ok, and thanks for the references. For the moment, I'd like to get straight
in my mind how this Hardinge spindle works. Maybe I can cut to the chase by
asking a couple of questions, since you have the drawing and may be able to
see the details with it.
A lathe spindle has to deal with four forces. First, the major radial load,
which usually is taken out by the front (spindle-nose-end) bearing. Second,
the minor radial load, which typically is the tail-end bearing. The ones I'm
questioning here are the other two: the thrust loads in each direction -- Z+
and Z-.
Which bearing takes out each of these two thrust loads? How far apart are
the front and rear bearings? Are they both single-row types, or is one a
double-row? Finally, do either of the bearings have a split race?
Thanks.
--
Ed Huntress
Ed Huntress
One now works in an unrelated industry, and was the sales manager. Another
is retired in Elmira; I spoke to him last summer -- he's occupied with other
interests. <g> Of the two tech guys I knew, one passed away and the other I
haven't spoken to for over 20 years, so it would be a little awkward.
Hardinge has had some rough times. I was doing some research (not
engineering) for them a little over two years ago, and not one of the people
I talked to then is still there.
I think we can find out what we need to know without them; I'm not
encouraged by the response of the service (dispatcher, I guess), who made it
pretty clear that no one there would know about the old machines. That work
probably has been taken up by third-party service organizations. Maybe
Gunner knows who that would be.
BTW, I didn't try the parts department, because I'm guessing that they know
parts numbers but not much about the engineering involved.
--
Ed Huntress
Mark Rand
wrote:
>
>Ok, and thanks for the references. For the moment, I'd like to get straight
>in my mind how this Hardinge spindle works. Maybe I can cut to the chase by
>asking a couple of questions, since you have the drawing and may be able to
>see the details with it.
>
>A lathe spindle has to deal with four forces. First, the major radial load,
>which usually is taken out by the front (spindle-nose-end) bearing. Second,
>the minor radial load, which typically is the tail-end bearing. The ones I'm
>questioning here are the other two: the thrust loads in each direction -- Z+
>and Z-.
>
>Which bearing takes out each of these two thrust loads? How far apart are
>the front and rear bearings? Are they both single-row types, or is one a
>double-row? Finally, do either of the bearings have a split race?
>
>Thanks.
AFAICT, the HLV-H has two identical angular contact bearings spaced a long way
apart with a spacer on the mandrel for the inner races and external clamping
for the outer races. I believe they are back-to-back rather than face-to-face,
but could be wrong.
The HLV has a pair of the same bearings as above back-to-back at the front.
clamped together by the outer races and a deep groove ball bearing at the rear
floating in a bore, but lightly loaded with a wave washer.
The HLV-H design is better than the HLV.
The HLV has a number of gearbox shafts with three bearings fighting against
each other. This results in the fitted C1 bearings coming out more sloppy than
C3 after a few decades. The headstock bearings are much more expensive than
6200C1s though. I don't know if the HLV-H has these problems.
Mark Rand
RTFM
Ed Huntress
"Mark Rand" <ra...@internettie.co.uk> wrote in message
news:dfntg5la1teissqbb...@4ax.com...
Ho-kay. Now, the reputation of Hardinge toolroom lathes is that the spindle
typically gets up to about body temperature or slightly above when they're
running and stabilized (this is second-hand info; I've never put my hand on
one). That's quite cool, but not out of reason for near-perfect bearings.
Apologies for doing this all in Fahrenheit and inch measurements, but if the
bearings are separated by, say, 8 inches, the spindle (and the spacer,
assuming it's steel) between them will expand by just under 0.002 in. with a
30 deg. F rise in temperature. (Steel expands at 7.3 x 10^-6 inch per inch,
per degree F, if anyone cares to check my calculations).
How do they cope with that? Does the headstock casting supposedly compensate
perfectly for that growth? Because 0.002 in. is enough to completely unload
any preloaded, high-quality bearings -- or to destroy them if they're each
facing the other way.
--
Ed Huntress
Mark Rand
>On Thu, 26 Nov 2009 13:22:11 -0500, "Ed Huntress" <hunt...@optonline.net>
>wrote:
>The HLV has a pair of the same bearings as above back-to-back at the front.
>clamped together by the outer races and a deep groove ball bearing at the rear
>floating in a bore, but lightly loaded with a wave washer.
Update, caused by going out to the shed and actually looking at the bearings I
took out...
The HLV-H and HLV front bearings are Fafnir 9111W1 angular contact. The HLV
rear is a 9110W1 angular contact.
Mark Rand
RTFM
Ed Huntress
Now I'm getting confused. If the HLV has a pair in front and one in the
rear, why is the rear bearing an angular-contact type? I can see that for
the HLVH, based on what's been said here.
--
Ed Huntress
Mark Rand
wrote:
>
>
>Ho-kay. Now, the reputation of Hardinge toolroom lathes is that the spindle
>typically gets up to about body temperature or slightly above when they're
>running and stabilized (this is second-hand info; I've never put my hand on
>one). That's quite cool, but not out of reason for near-perfect bearings.
>
>Apologies for doing this all in Fahrenheit and inch measurements, but if the
>bearings are separated by, say, 8 inches, the spindle (and the spacer,
>assuming it's steel) between them will expand by just under 0.002 in. with a
>30 deg. F rise in temperature. (Steel expands at 7.3 x 10^-6 inch per inch,
>per degree F, if anyone cares to check my calculations).
>
>How do they cope with that? Does the headstock casting supposedly compensate
>perfectly for that growth? Because 0.002 in. is enough to completely unload
>any preloaded, high-quality bearings -- or to destroy them if they're each
>facing the other way.
I had wondered about that.
Close inspection of the parts diagram (anyone want to give me an HLVH-H so I
know for sure, I missed out on two before I got the HLV), shows that the inner
races are separated by a spacer and clamped between the mandrel nose and the
pulley. The outer races are separated by a spacer closely fitted and keyed to
the headstock casting (can be assumed to be thermally part of it). The front
outer race is restrained on both sides, but the rear outer race is only
restrained on the "inside"
So, assuming the mandrel heats up more rapidly than the headstock casting,
it'll get loose before regaining equilibrium. I don't know how good a fit the
rear outer race is in the headstock, but one must assume that it's free enough
to move before the bearing takes harm. There is no preload spring or similar
shown in the parts diagrams.
This also tends to imply that you should run your Hardinge at your desired
speed for about an hour to heat soak it, before doing work of the highest
precision. But only if you're anal about it!
We had an example where differential expansion ate bearings, a model air
turbine had an imperfect bearing retaining arrangement. Ate two sets of
bearings before they worked out the cause of the problem wasn't the mist
lubrication system. Matched pairs of 7" bore taper roller bearings at �6,000 a
set :-O.
Mark Rand
RTFM
Ed Huntress
I will if I get anything useful. There's a big book about the history of the
Philips Stirlings, which I've never seen. I'll have to ask one of the
experts if it contains any good info on lubrication.
The basic story is that free-piston Stirlings are using dynamic gas
bearings -- which is to say, the pistons are designed to center themselves
on a film of the working gas. Low-temperature-differential Stirlings
generally run dry, often with graphite pistons (another issue; it's not as
clear as it seems, because synthetic graphite is not lubricious). Other
bearings in those engines are dry-running ball bearings.
Small stationary engines sometimes are made with oiled bottom ends and, in
the case of beta Stirlings, with Rulon or other syntheic seals to keep the
oil out of the hot end. And sometimes they run dry, too. Here it's important
to avoid lateral loads on the pistons, by using rhombic drives, Scotch
yokes, or other mechanisms that result in straight-line forces applied to
the pistons.
I don't know about the big automotive types. There have been a number of
successful ones, from Ford, Saab, and others, so there must be a way. I'm
looking forward to learning more.
The basic issue, BTW, is that oil that gets into the heat exchangers ruins
their efficiency. And oil that gets into the hot end will carbonize. This is
one of the big engineering problems with Stirlings, as you've apparently
heard.
If it gets too complicated, it can become a solution in search of a problem.
<g> When I was writing about machine tools and people were trying to sell me
on the Hexapod, it became one of those. Likewise, an
elliptical-piston-machining lathe I was once involved with.
--
Ed Huntress
Mark Rand
wrote:
>
>Now I'm getting confused. If the HLV has a pair in front and one in the
>rear, why is the rear bearing an angular-contact type? I can see that for
>the HLVH, based on what's been said here.
Ditto.
I can only put it down to the fact that the HLV seems to incorporate quite a
lot of design decisions that don't make sense from an engineering point of
view, unless you assume that more expensive is automatically better. Like my
case earlier where three C3 or two C1 bearings would outlast three C1 bearings
on a shaft and other oddities. I guess it is a 60 year old design and there
were many improvements made over the years.
Gunner Asch
wrote:
>On Thu, 26 Nov 2009 13:22:11 -0500, "Ed Huntress" <hunt...@optonline.net>
No..they dont. But the 2 head stock bearings are still $350 for the
pair..or more.
Gunner
>
>
>Mark Rand
>RTFM
Gunner Asch
wrote:
>On Thu, 26 Nov 2009 16:06:51 -0500, "Ed Huntress" <hunt...@optonline.net>
>wrote:
>
>>
>
>>
>>Ho-kay. Now, the reputation of Hardinge toolroom lathes is that the spindle
>>typically gets up to about body temperature or slightly above when they're
>>running and stabilized (this is second-hand info; I've never put my hand on
>>one). That's quite cool, but not out of reason for near-perfect bearings.
>>
>>Apologies for doing this all in Fahrenheit and inch measurements, but if the
>>bearings are separated by, say, 8 inches, the spindle (and the spacer,
>>assuming it's steel) between them will expand by just under 0.002 in. with a
>>30 deg. F rise in temperature. (Steel expands at 7.3 x 10^-6 inch per inch,
>>per degree F, if anyone cares to check my calculations).
>>
>>How do they cope with that? Does the headstock casting supposedly compensate
>>perfectly for that growth? Because 0.002 in. is enough to completely unload
>>any preloaded, high-quality bearings -- or to destroy them if they're each
>>facing the other way.
>
>
>I had wondered about that.
>
>Close inspection of the parts diagram (anyone want to give me an HLVH-H so I
>know for sure, I missed out on two before I got the HLV), shows that the inner
>races are separated by a spacer and clamped between the mandrel nose and the
>pulley. The outer races are separated by a spacer closely fitted and keyed to
>the headstock casting (can be assumed to be thermally part of it). The front
>outer race is restrained on both sides, but the rear outer race is only
>restrained on the "inside"
>
The spacer isnt keyed to anything. Its simply on the spindle tube.
Almost an interference fit.
>So, assuming the mandrel heats up more rapidly than the headstock casting,
>it'll get loose before regaining equilibrium. I don't know how good a fit the
>rear outer race is in the headstock, but one must assume that it's free enough
>to move before the bearing takes harm. There is no preload spring or similar
>shown in the parts diagrams.
When the spindle gets hot..it expands and presses the bearings
harder..not softer.
>
>This also tends to imply that you should run your Hardinge at your desired
>speed for about an hour to heat soak it, before doing work of the highest
>precision. But only if you're anal about it!
While they will indeed cut to a couple tenths..few people do.
>
>We had an example where differential expansion ate bearings, a model air
>turbine had an imperfect bearing retaining arrangement. Ate two sets of
>bearings before they worked out the cause of the problem wasn't the mist
>lubrication system. Matched pairs of 7" bore taper roller bearings at �6,000 a
>set :-O.
>
>
>
>Mark Rand
>RTFM
"Aren't cats Libertarian? They just want to be left alone.
Joseph Gwinn
"Ed Huntress" <hunt...@optonline.net> wrote:
> "Joseph Gwinn" <joeg...@comcast.net> wrote in message
> news:joegwinn-A788B4...@news.giganews.com...
> > In article <4b0d6eba$0$22525$607e...@cv.net>,
> > "Ed Huntress" <hunt...@optonline.net> wrote:
> >
[snip]
I had heard that seals were a big problem, and noticed that only NASA
seemed to be able to use Stirling cycle engines for anything, but didn't
know the details.
[snip]
My impression is that Slocum has come to this conclusion about concrete
cored machine tools as well. But when you mentioned trying to design
concrete machine tools, I wanted to be sure you knew of this literature.
And his damped boring bar is something a HSM could easily fabricate.
Joe Gwinn
Mark Rand
wrote:
>On Thu, 26 Nov 2009 23:19:02 +0000, Mark Rand <ra...@internettie.co.uk>
>wrote:
>
>>So, assuming the mandrel heats up more rapidly than the headstock casting,
>>it'll get loose before regaining equilibrium. I don't know how good a fit the
>>rear outer race is in the headstock, but one must assume that it's free enough
>>to move before the bearing takes harm. There is no preload spring or similar
>>shown in the parts diagrams.
>
>When the spindle gets hot..it expands and presses the bearings
>harder..not softer.
>>
Have I got it bass ackwards?
I had assumed that the bearings were arranged:-
>====<
Although, thinking about it.
Given that these are non-separable bearings, rather than fall-apart magneto
type, expansion in the "loosening" direction would still serve to tighten
things up until the point where the bearings broke...and that ain't going to
happen.
Mark Rand
RTFM
Mark Rand
>On Thu, 26 Nov 2009 23:19:02 +0000, Mark Rand <ra...@internettie.co.uk>
>wrote:
>
>>
>>Close inspection of the parts diagram (anyone want to give me an HLVH-H so I
>>know for sure, I missed out on two before I got the HLV), shows that the inner
>>races are separated by a spacer and clamped between the mandrel nose and the
>>pulley. The outer races are separated by a spacer closely fitted and keyed to
>>the headstock casting (can be assumed to be thermally part of it). The front
>>outer race is restrained on both sides, but the rear outer race is only
>>restrained on the "inside"
>>
>
>The spacer isnt keyed to anything. Its simply on the spindle tube.
>Almost an interference fit.
>
I didn't mean the spacer on the spindle, I meant the one in the headstock
casting. The parts diagram seems to imply that there's a dowel going through
the top of the headstock casting to hold it in place. Although the book
doesn't show a part number for either part...
Regards
Mark Rand
RTFM
Gunner Asch
wrote:
>On Thu, 26 Nov 2009 18:28:28 -0800, Gunner Asch <gun...@NOSPAMlightspeed.net>
>wrote:
>
>>On Thu, 26 Nov 2009 23:19:02 +0000, Mark Rand <ra...@internettie.co.uk>
>>wrote:
>>
>
>>>So, assuming the mandrel heats up more rapidly than the headstock casting,
>>>it'll get loose before regaining equilibrium. I don't know how good a fit the
>>>rear outer race is in the headstock, but one must assume that it's free enough
>>>to move before the bearing takes harm. There is no preload spring or similar
>>>shown in the parts diagrams.
>>
>>When the spindle gets hot..it expands and presses the bearings
>>harder..not softer.
>>>
>
>Have I got it bass ackwards?
>
>I had assumed that the bearings were arranged:-
>
>>====<
>
>
>Although, thinking about it.
>
>Given that these are non-separable bearings, rather than fall-apart magneto
>type, expansion in the "loosening" direction would still serve to tighten
>things up until the point where the bearings broke...and that ain't going to
>happen.
>
>Mark Rand
>RTFM
Bingo. <G>
The folks at Hardinge were pretty damned smart ol farts <G>
Gunner
Gunner Asch
wrote:
>On Thu, 26 Nov 2009 18:28:28 -0800, Gunner Asch <gun...@NOSPAMlightspeed.net>
>wrote:
>
>>On Thu, 26 Nov 2009 23:19:02 +0000, Mark Rand <ra...@internettie.co.uk>
>>wrote:
>>
>
>>>
>>>Close inspection of the parts diagram (anyone want to give me an HLVH-H so I
>>>know for sure, I missed out on two before I got the HLV), shows that the inner
>>>races are separated by a spacer and clamped between the mandrel nose and the
>>>pulley. The outer races are separated by a spacer closely fitted and keyed to
>>>the headstock casting (can be assumed to be thermally part of it). The front
>>>outer race is restrained on both sides, but the rear outer race is only
>>>restrained on the "inside"
>>>
>>
>>The spacer isnt keyed to anything. Its simply on the spindle tube.
>>Almost an interference fit.
>>
>
>I didn't mean the spacer on the spindle, I meant the one in the headstock
>casting. The parts diagram seems to imply that there's a dowel going through
>the top of the headstock casting to hold it in place. Although the book
>doesn't show a part number for either part...
>
Ayup..there is indeed a dowel holding the "spindle cavity" Stuff in the
rough headstock. As its not removable..the thing is simply part of the
manufacturing process and is not intended for removal. Though I did see
one that was partially out once.
They figure the drunk on the forklift hit it about 15 mph..perfect shot
on the end of the collet closer with one fork of a 12,000 lb forklift.
Moved the machine into the next room..right through a wall and the mens
bathroom.....<VBG>
The Stuff was sticking out about 1.5"
So it was put in pretty damned good.
They pulled the headstock and sent it back to Hardinge. It was returned
about 3 weeks later, all back in good running condition. Didnt even have
to replace the spindle...but it did need a new collet closer.
Good machines indeed
Gunner
Gunner
>
>Regards
Ned Simmons
<hunt...@optonline.net> wrote:
I can't see any way the bearings can be arranged other than the usual
back-to-back, so a thrust load directed toward the spindle nose is
carried by the nose bearing and an opposite thrust by the tail
bearing.
>How far apart are
>the front and rear bearings?
Scaling the assembly drawing and using some exernal dimensions from my
lathe as a reference, it looks like the spacers are about 6-1/2" long.
(My lathe is a Taiwanese Feeler, but other than using metric fasteners
it's a remarkably faithful copy of a Hardinge.)
Are they both single-row types, or is one a
>double-row? Finally, do either of the bearings have a split race?
Single row. If by split race you mean a fractured race that separates
into two semicircles, no.
>
>Thanks.
--
Ned Simmons
Ned Simmons
<gun...@NOSPAMlightspeed.net> wrote:
You guys have me confused now. I agree with Mark's earlier
interpretation of the assembly drawing, which I assume is the same as
the one I'm looking at. It seems to me that the bearings must be
installed in a normal back-to-back arrangement (with the spacer in
between, of course), otherwise there'd be nothing holding the outer
race of the rear bearing in place. If this is the case, the preload
will fall as the temperature of the inner spacer and spindle rises
above the temp of outer spacer. Am I missing something?
Back-to-back vs. face-to-face mounting:
http://www.lawrencepumps.com/images04/news_vol3_i04_img3.gif
--
Ned Simmons
Ed Huntress
Ok, I get the picture now. Thanks, Ned. Oh, by "split race" I meant
single-row, deep-groove bearings in which the outer race is split
peripherally. They can be adjusted for preload and can handle radial loads
and thrust loads in both directions. I've never seen one, but I've seen
drawings of them.
--
Ed Huntress
Ed Huntress
If all of this is sinking in correctly, it sounds like the outer spacer is
designed to heat and expand at the same rate as the inner spacer -- or close
enough for it to work. Because it still looks to me like the whole assembly
is going to break or unload if one of them expands significantly faster than
the other.
With the outer spacer, it saves one bearing but adds the spacer. And the
whole thing, I'll bet, was developed experimentally.
To get back to my original questions, that wouldn't work for the home-built
lathe I'm talking about. The complication of holding the outer spacer, and
getting the expansions right, isn't something I think you could do as a
one-shot deal. And the concrete head would add to the differential-spacing
woes.
--
Ed Huntress
Jim Wilkins
> ...
>
> To get back to my original questions, that wouldn't work for the home-built
> lathe I'm talking about. The complication of holding the outer spacer, and
> getting the expansions right, isn't something I think you could do as a
> one-shot deal. And the concrete head would add to the differential-spacing
> woes.
But if you built it yourself and are the only user you know you have
to pay extra attention for problems. You could file the left-hand
bearing seat on the spindle to a moderate press fit so it can slide if
it has to, or not run it long and fast enough to warm up. You could
rub some wax on the spindle nose and shut off if it melts and turns
shiny.
Prototypes are full of gotchas and caveats but they still work well
for the people who built them. You might have to hire (or be) a tech
writer to put together a lengthy manual so someone else could safely
use the machine.
jsw
Ed Huntress
On Nov 28, 2:20 am, "Ed Huntress" <huntre...@optonline.net> wrote:
> ...
>
> To get back to my original questions, that wouldn't work for the
> home-built
> lathe I'm talking about. The complication of holding the outer spacer, and
> getting the expansions right, isn't something I think you could do as a
> one-shot deal. And the concrete head would add to the differential-spacing
> woes.
> Ed Huntress
>But if you built it yourself and are the only user you know you have
>to pay extra attention for problems. You could file the left-hand
>bearing seat on the spindle to a moderate press fit so it can slide if
>it has to, or not run it long and fast enough to warm up. You could
>rub some wax on the spindle nose and shut off if it melts and turns
>shiny.
Right. But if the bearing slips, you have no Z-axis stiffness. The spindle
would slide in or out when you took facing cuts or faced the back of a
bearing retainer or whatever on a shaft.
The traditional setup, with two facing, angular-contact bearings at the
front, and one floating bearing at the rear, solves all of those problems.
There isn't enough space between the front bearings for thermal growth to be
a problem. And both thrust loads, Z+ and Z-, are taken out at the front.
Then the rear bearing can float a bit with no loss of axial stiffness. It
needs to be preloaded in the radial direction to maintain radial stiffness,
but there, too, there is more room for slack than at the front.
Jim Wilkins
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
> >...You could file the left-hand
> >bearing seat on the spindle to a moderate press fit so it can slide if
> >it has to,...>
> Right. But if the bearing slips, you have no Z-axis stiffness. The spindle
> would slide in or out when you took facing cuts or faced the back of a
> bearing retainer or whatever on a shaft.
>
> The traditional setup, with two facing, angular-contact bearings at the
> front, and one floating bearing at the rear, solves all of those problems.
> There isn't enough space between the front bearings for thermal growth to be
> a problem. And both thrust loads, Z+ and Z-, are taken out at the front.
> Then the rear bearing can float a bit with no loss of axial stiffness. It
> needs to be preloaded in the radial direction to maintain radial stiffness,
> but there, too, there is more room for slack than at the front.
>
> >jsw
There's no conflict, I suggested a non-precision manual way to make
the rear bearing float without being too loose when you are boot-
strapping the lathe. I'd figure out the preloading details on the
chuck end after a trial assembly to see if the bearings are good
enough. Some combination of easily made spacers and shims ought to
work.
I've found that if I order the parts to build it one way, perhaps not
the absolute best one, they will allow it to be assembled several
other better ways that I think of only after trying the first one. I
do have to know any hard limits like bearing PV and buy to meet them,
but the mounting details can safely wait.
On our plain bearing, leather belt driven South Bends a ball thrust
bearing on the pulley side of the rear/left spindle bearing absorbs
thrust and a threaded shaft clamp on the outside takes up play. The
instructions are to hand-tighten it, then back off 3/8" (of rotation)
and lock the clamp screw. The chuck end is free to slide.
jsw
Ed Huntress
On Nov 28, 1:14 pm, "Ed Huntress" <huntre...@optonline.net> wrote:
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
> >...You could file the left-hand
> >bearing seat on the spindle to a moderate press fit so it can slide if
> >it has to,...>
> Right. But if the bearing slips, you have no Z-axis stiffness. The spindle
> would slide in or out when you took facing cuts or faced the back of a
> bearing retainer or whatever on a shaft.
>
> The traditional setup, with two facing, angular-contact bearings at the
> front, and one floating bearing at the rear, solves all of those problems.
> There isn't enough space between the front bearings for thermal growth to
> be
> a problem. And both thrust loads, Z+ and Z-, are taken out at the front.
> Then the rear bearing can float a bit with no loss of axial stiffness. It
> needs to be preloaded in the radial direction to maintain radial
> stiffness,
> but there, too, there is more room for slack than at the front.
>
> >jsw
>There's no conflict, I suggested a non-precision manual way to make
>the rear bearing float without being too loose when you are boot-
>strapping the lathe. I'd figure out the preloading details on the
>chuck end after a trial assembly to see if the bearings are good
>enough. Some combination of easily made spacers and shims ought to
>work.
How do you take out both Z+ and Z- axial loads from one single-row bearing?
--
Ed Huntress
Jim Wilkins
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
...
>
I don't. On Nov 24 I wrote:
"I would try pillow blocks with setscrews or shaft clamps and jam two
of them together to get preloaded angular contact at the working end
of the spindle. Then the spindle (key-slotted shafting) could be
easily swapped so you could weld a plate on one to mount a chuck, for
instance."
The details depend on whatever I find/order/make for a spindle and
bearings and drive pulley.
jsw
Ed Huntress
Oh, then we're talking about two different things. I was still wondering
about applying the single bearing to each end of the spindle, like the
Hardinge HLVH.
--
Ed Huntress
Jim Wilkins
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
>
> news:09aee681-655b-402d...@z7g2000vbl.googlegroups.com...
> On Nov 28, 7:03 pm, "Ed Huntress" <huntre...@optonline.net> wrote:
>
>
>
>
>
> > "Jim Wilkins" <kb1...@gmail.com> wrote in message
> ...
>
> > How do you take out both Z+ and Z- axial loads from one single-row
> > bearing?
> > Ed Huntress
> >I don't. On Nov 24 I wrote:
>
> >"I would try pillow blocks with setscrews or shaft clamps and jam two
> >of them together to get preloaded angular contact at the working end
> >of the spindle. Then the spindle (key-slotted shafting) could be
> >easily swapped so you could weld a plate on one to mount a chuck, for
> >instance."
>
> >The details depend on whatever I find/order/make for a spindle and
> >bearings and drive pulley.
>
> >jsw
>
> Oh, then we're talking about two different things. I was still wondering
> about applying the single bearing to each end of the spindle, like the
> Hardinge HLVH.
>
> --
> Ed Huntress
Maybe you could machine shoulders on the spindle and pipe sleeve
spaced for the cold spindle, then place an O ring between the outer
race and its retaining cap on the chuck end. Tighten the retaining cap
if the tool chatters or digs in when turning a left-side shoulder,
loosen it if the spindle binds. There ought to be a compromise where
you can get some work done.
jsw
Ned Simmons
<hunt...@optonline.net> wrote:
The HLVH layout is extreme, but some space between the front bearing
pair is not unusual. I'm looking at a cross section of a 10EE
headstock and it appears the spacers are about 2-1/2" long. The
support at the tail is an unspaced pair of angular contact bearings.
Top speed of an EE is about 1000RPM higher than an HLVH.
The bearings at the nose of a Bridgeport spindle are separated perhaps
1-1/2". In this case there's a single deep groove bearing at the top
of the quill. A BP spindle running at top speed gets much hotter than
an HLVH.
Grinder spindles typically have the bearings pairs mounted directly
back-to-back.
--
Ned Simmons
Ed Huntress
That generally agrees with what I've seen, although I haven't had any
spindles apart for a few decades. Thirty degrees F produces about 0.001 in.
of growth in about 5 inches of length. That shouldn't be a problem for
ordinary bearings, which are less that perfect all around; there's a little
room for elastic compression.
As it's been explained to me, the problem becomes more critical as the
bearing class goes up. The Class 9 bearings in a Hardinge HLVH must be very
touchy in terms of the growth they'll tolerate.
--
Ed Huntress
Ed Huntress
I'm sure there are many possible solutions. But the old designs have lasted
for several generations, for a reason. Aside from the plain-bearing spindles
(which I have and like -- mine hasn't been adjusted in 50 years, and it is
well within spec), various types of roller bearings have been used
successfully, usually with the thrust taken out in a closely-coupled pair at
the head end.
I don't see it as a big problem.
--
Ed Huntress
Gunner Asch
>>With the outer spacer, it saves one bearing but adds the spacer. And the
>>whole thing, I'll bet, was developed experimentally.
>
>The HLVH layout is extreme, but some space between the front bearing
>pair is not unusual. I'm looking at a cross section of a 10EE
>headstock and it appears the spacers are about 2-1/2" long. The
>support at the tail is an unspaced pair of angular contact bearings.
>Top speed of an EE is about 1000RPM higher than an HLVH.
3000 rpm for the HLV-H
4000 rpm for the DV-59 which uses a smaller spindle and headstock..but
only 2 bearings
Gunner
Jim Wilkins
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
> ...
> Ed Huntress
The problem is making the first headstock spindle without another
lathe. Once you have it you can machine a better one.
In my case someone would likely offer me a good lathe cheap *after*
seeing the one I struggled to make.
jsw
Ed Huntress
I wouldn't attempt this without access to another lathe, unless someone made
it a group or club project and made the necessary machined parts available
for a reasonable price.
--
Ed Huntress
Jim Wilkins
> "Jim Wilkins" <kb1...@gmail.com> wrote in message
>
> news:02379ed6-bab1-49a8...@p8g2000yqb.googlegroups.com...
> On Nov 28, 11:19 pm, "Ed Huntress" <huntre...@optonline.net> wrote:
>
> > "Jim Wilkins" <kb1...@gmail.com> wrote in message
> > ...
> > I'm sure there are many possible solutions. ...
> > Ed Huntress
> >The problem is making the first headstock spindle without another
> >lathe. Once you have it you can machine a better one.
>
> >In my case someone would likely offer me a good lathe cheap *after*
> >seeing the one I struggled to make.
>
> >jsw
>
> I wouldn't attempt this without access to another lathe, unless someone made
> it a group or club project and made the necessary machined parts available
> for a reasonable price.
>
> --
> Ed Huntress
I think it could be achieved starting with a simple machine that's
adjusted into place. For example my dead-center lathe could bore the
headstock pipe for your cast concrete one. Slide the headstock down
the ways over a long fixed boring bar.
The practical application is temporary oversized equipment to
recondition old worn machines. I'd like to rig up a milling head with
enough X and Y travel to clean up the ways of my surface grinder. It
only needs to slide along one axis while cutting, and can rest on
parallels for the other axis.
jsw
Ned Simmons
<hunt...@optonline.net> wrote:
>>
>> The HLVH layout is extreme, but some space between the front bearing
>> pair is not unusual. I'm looking at a cross section of a 10EE
>> headstock and it appears the spacers are about 2-1/2" long. The
>> support at the tail is an unspaced pair of angular contact bearings.
>> Top speed of an EE is about 1000RPM higher than an HLVH.
>>
>> The bearings at the nose of a Bridgeport spindle are separated perhaps
>> 1-1/2". In this case there's a single deep groove bearing at the top
>> of the quill. A BP spindle running at top speed gets much hotter than
>> an HLVH.
>>
>> Grinder spindles typically have the bearings pairs mounted directly
>> back-to-back.
>>
>> --
>> Ned Simmons
>
>That generally agrees with what I've seen, although I haven't had any
>spindles apart for a few decades. Thirty degrees F produces about 0.001 in.
>of growth in about 5 inches of length.
One thing that we've neglected here is that this is, at least
potentially, a self compensating system. As the spindle warms up and
expands the preload drops, reducing the heat generated in the bearing.
The problem is coming up with a design that will settle at a
reasonable equilibrium under the normal range of operating speeds and
loadings. It seems Hardinge has been able to do this.
> That shouldn't be a problem for
>ordinary bearings, which are less that perfect all around; there's a little
>room for elastic compression.
>
>As it's been explained to me, the problem becomes more critical as the
>bearing class goes up. The Class 9 bearings in a Hardinge HLVH must be very
>touchy in terms of the growth they'll tolerate.
I've never heard that and find it hard to swallow. If a lower class
bearing has imperfections that allow it to deflect more easily, that
implies there are areas of high stress that would be more sensitive to
damage. I can see where a bearing with more accurate geometry might be
stiffer as a result of better stress distribution, but I'd expect that
would make it more robust, not less.
--
Ned Simmons
Ed Huntress
There are. That's why they don't last as long if both types are properly
applied. Unless it's overloaded, a Class 9 bearing will run until hell
freezes over, while a lesser bearing will eventually spall and fail. That
assumes that they aren't abused and brinelled, or otherwise damaged.
> I can see where a bearing with more accurate geometry might be
> stiffer as a result of better stress distribution...
Yes.
> but I'd expect that
> would make it more robust, not less.
It will last longer in proper service. It also is more susceptible to
overloading from thermal growth, misalignment, etc. If you're going to use
Class 9, everything in the setup had better be perfect. If it is, it will
outlast a lesser-quality bearing.
--
Ed Huntress
Ned Simmons
<hunt...@optonline.net> wrote:
>
>"Ned Simmons" <ne...@nedsim.com> wrote in message
>news:2lp5h5h56nhukmrsp...@4ax.com...
>> On Sat, 28 Nov 2009 23:08:15 -0500, "Ed Huntress"
>> <hunt...@optonline.net> wrote:
>>
>>
>>> That shouldn't be a problem for
>>>ordinary bearings, which are less that perfect all around; there's a
>>>little
>>>room for elastic compression.
>>>
>>>As it's been explained to me, the problem becomes more critical as the
>>>bearing class goes up. The Class 9 bearings in a Hardinge HLVH must be
>>>very
>>>touchy in terms of the growth they'll tolerate.
>>
>> I've never heard that and find it hard to swallow. If a lower class
>> bearing has imperfections that allow it to deflect more easily, that
>> implies there are areas of high stress that would be more sensitive to
>> damage.
>
>There are. That's why they don't last as long if both types are properly
>applied. Unless it's overloaded, a Class 9 bearing will run until hell
>freezes over, while a lesser bearing will eventually spall and fail. That
>assumes that they aren't abused and brinelled, or otherwise damaged.
Not quite. Unless very lightly loaded, all bearings will eventually
fatigue and fail by spalling. Very light loads will cause problems
related to skidding of the balls.
>
>> I can see where a bearing with more accurate geometry might be
>> stiffer as a result of better stress distribution...
>
>Yes.
>
>> but I'd expect that
>> would make it more robust, not less.
>
>It will last longer in proper service. It also is more susceptible to
>overloading from thermal growth, misalignment, etc. If you're going to use
>Class 9, everything in the setup had better be perfect. If it is, it will
>outlast a lesser-quality bearing.
This doesn't make sense to me. If a high ABEC class bearing will
outlast a lower class bearing under ideal conditions, what's the
mechanism that will cause it to fail sooner in a less than ideal
installation?
--
Ned Simmons
Jim Stewart
>>> I can see where a bearing with more accurate geometry might be
>>> stiffer as a result of better stress distribution...
>> Yes.
>>
>>> but I'd expect that
>>> would make it more robust, not less.
>> It will last longer in proper service. It also is more susceptible to
>> overloading from thermal growth, misalignment, etc. If you're going to use
>> Class 9, everything in the setup had better be perfect. If it is, it will
>> outlast a lesser-quality bearing.
>
> This doesn't make sense to me. If a high ABEC class bearing will
> outlast a lower class bearing under ideal conditions, what's the
> mechanism that will cause it to fail sooner in a less than ideal
> installation?
Well, he didn't say fail catastrophically. It could be
that it degrades in performance and doesn't meet class
9 specs any longer.
Ned Simmons
wrote:
Perhaps, but that's not how I read it. Clearly it doesn't make sense
economically to stick an expensive bearing in an inferior gadget, but
I can't come up with any reason it wouldn't last as long as an ABEC 1
bearing.
--
Ned Simmons
Ed Huntress
There's nothing much to "crush." A given amount of displacement of one race
relative to the other can produce a substantially higher preload in a
higher-class bearing. The difference may be slight, but small variations in
the percentage of yield strength that a bearing is subject to will produce
large variations in its fatigue life -- in other words, the time it takes
for the bearing balls or the race to spall.
--
Ed Huntress
Ed Huntress
Maybe. I've thought about some of this in the past, and I don't see being
able to bore the headstock from the bed without a pretty fancy, and strong,
temporary boring rig. If it was just a straight bore, maybe. But I've
changed my thinking on that to include a tube bored on another lathe; a
careful setup to cast it in place when the headstock is cast; and a
honing/lapping rig mounted on the new lathe's bedways, rather than boring,
to finish it off. The loads will be much less and you won't need a
controlled feedrate. The whole affair would be simpler.
But I'm not saying I have all the answers for this. It's just a lot of
thinking and speculating on my part. Nor would I want to discourage anyone
else who wants to give it a try. Viva the experiments.
As for finish-machining bedways, you might like to see my idea for a
right-angle grinding head that moves on ordinary, low-accuracy ways
(Thompson round ways), with two axes of stepping motors that respond to
optical drives that follow a laser beam -- or maybe you wouldn't want to see
it, come to think of it. It was pretty rough and crude, but there's an idea
there. (No, I don't have any CAD files of it. I sketched it around 30 years
ago.)
--
Ed Huntress