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Rotary Broaching
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Bob La Londe
Nov 30, 2016, 8:54:51 PM11/30/16
to
Now I know the easiest way to do what I want is with a push broach and make
them as two pieces, but I want to make some specialty hex drivers with a one
piece body. That leaves me with rotary broaching. The thing is I am not
going to make a bunch of them so buying a rotary broach holder or spending a
day making one isn't all that wise of use of my time or money. However once
I was setup to do it rotary broach inserts are a lot cheaper than push
broaches.
Recently I had need to do some cross drilling that would have been easiest
with a preset cross drill on the lathe. Its slow and tedious to center up
and drill the part on the mill, but of course I can do it. I don't have to
do it often so again making a cross drill for the lathe isn't good use of my
time.
Then I had an aha moment. Make it fairly robust and use it for rotary
broaching as well. Centering would be a little tedious, but getting my 1
degree back angle from center would be dead easy to do after that. Then
lock down all the gibs not in use and advance the carriage. I doubt it
would ever work on the mini lathe or the small lathe, but maybe the PM1440
could handle it.
If I can use the same tool for both applications it almost makes it worht
making one. I might still know where to find it by the next time I need it.
Driven with hand held drill when cross drilling and of course driven by the
stock when rotary broaching.
I don't think I've ever cross tapped stock in the lathe, but if I don't see
why I could not add enough functionality to do that too if I need to.
So what's wrong with it? I know rotary broaching takes a lot of power. The
lathe is big, but its only 3HP. Flex in the compound, cross slide, and
carriage could be an issue. If a spacer is used internally in the cross
dril that rides on a thrust bearing I think the drill itself could take it.
I also considered bronze bushing with a 1/2 shaft collet chuck because the
bronze can take so much force.
them as two pieces, but I want to make some specialty hex drivers with a one
piece body. That leaves me with rotary broaching. The thing is I am not
going to make a bunch of them so buying a rotary broach holder or spending a
day making one isn't all that wise of use of my time or money. However once
I was setup to do it rotary broach inserts are a lot cheaper than push
broaches.
Recently I had need to do some cross drilling that would have been easiest
with a preset cross drill on the lathe. Its slow and tedious to center up
and drill the part on the mill, but of course I can do it. I don't have to
do it often so again making a cross drill for the lathe isn't good use of my
time.
Then I had an aha moment. Make it fairly robust and use it for rotary
broaching as well. Centering would be a little tedious, but getting my 1
degree back angle from center would be dead easy to do after that. Then
lock down all the gibs not in use and advance the carriage. I doubt it
would ever work on the mini lathe or the small lathe, but maybe the PM1440
could handle it.
If I can use the same tool for both applications it almost makes it worht
making one. I might still know where to find it by the next time I need it.
Driven with hand held drill when cross drilling and of course driven by the
stock when rotary broaching.
I don't think I've ever cross tapped stock in the lathe, but if I don't see
why I could not add enough functionality to do that too if I need to.
So what's wrong with it? I know rotary broaching takes a lot of power. The
lathe is big, but its only 3HP. Flex in the compound, cross slide, and
carriage could be an issue. If a spacer is used internally in the cross
dril that rides on a thrust bearing I think the drill itself could take it.
I also considered bronze bushing with a 1/2 shaft collet chuck because the
bronze can take so much force.
Jim Wilkins
Nov 30, 2016, 11:26:59 PM11/30/16
to
"Bob La Londe" <no...@none.com99> wrote in message
news:o1nvqr$dvc$1...@dont-email.me...
I don't understand what you are getting at. Maybe this will help?
5C collets and a set of these blocks are great for clamping and
milling round work in a mill.
http://www.ebay.com/itm/like/310713155574?lpid=82&chn=ps&ul_noapp=true
The round closer nuts allow the work to stand upright, the lever
closer is faster if it's horizontal. There are several simple ways to
center the work under the spindle, such as temporarily placing the
0.500" step of an edge finder in an upright 1/2" collet while the
shank of the finder is in a mill collet, then aligning them and
locking the Y axis. You can also center on the point of a tap held in
a collet.
Once the collet and spindle are coaxial you can drill cross holes,
mill keyways, fishmouth the end, whatever you want, and rotate the
work in multiples of 60 or 90 degrees. Milling two, four or six wrench
flats is simple and doesn't require centering, just an end stop to
relocate the block after turning it..
Since my lathe accepts 5C I have a 3-jaw like this and the Sherline
4-jaw. They are small enough to fit on the milling setup.
http://www.ebay.com/itm/like/331114009913?lpid=82&chn=ps&ul_noapp=true
I could probably get away with buying 5C collets only for the few
sizes of ground drill rod I stock. After turning the part on the end
of the rod, usually the only operation on the cutoff end is facing it,
in a 3-jaw.
A 5c spin index lets you index to integer degrees. They aren't my
choice for heavier cuts like milling a hex head on 1" drill rod.
http://www.grizzly.com/products/5-C-Spin-Index/G5649?utm_campaign=zPage&utm_source=grizzly.com
I broach internal hex openings for Allen keys by grinding a smaller
size key to a sharp-edged flat end and mounting it in a boring bar
holder.
The six-sided index attached to the spindle could be a sheetmetal disk
with cutouts that I hold against a block resting on the ways with one
hand while making the cuts with the other. I tried just aligning lines
drawn on the chuck with an index but the work shifted too much diring
the cuts.
My lathe has a threaded spindle that easily holds a homemade indexing
disk (an old car timing degree wheel) behind the chuck or the spindle
nut that pops out the collet adapter.
http://www.homegunsmith.com/archive/T14937.html
First drill the hex recess to the nominal size, the distance across
the wrench flats. Select an Allen key that fits into it and grind it
flat or slightly beveled on the end and mount it in a tool holder with
the flats top and bottom and the cutting corner at center height,
towards you. Feed it in to shave off a thou or so from each of the six
corner, advance outward and repeat until the proper sized key fits.
The tool doesn't cut freely unless slightly angled, and deflects too
much to calculate the total feed distance.
I added the other groups to clutter them up the way they do to us.
--jsw
news:o1nvqr$dvc$1...@dont-email.me...
5C collets and a set of these blocks are great for clamping and
milling round work in a mill.
http://www.ebay.com/itm/like/310713155574?lpid=82&chn=ps&ul_noapp=true
The round closer nuts allow the work to stand upright, the lever
closer is faster if it's horizontal. There are several simple ways to
center the work under the spindle, such as temporarily placing the
0.500" step of an edge finder in an upright 1/2" collet while the
shank of the finder is in a mill collet, then aligning them and
locking the Y axis. You can also center on the point of a tap held in
a collet.
Once the collet and spindle are coaxial you can drill cross holes,
mill keyways, fishmouth the end, whatever you want, and rotate the
work in multiples of 60 or 90 degrees. Milling two, four or six wrench
flats is simple and doesn't require centering, just an end stop to
relocate the block after turning it..
Since my lathe accepts 5C I have a 3-jaw like this and the Sherline
4-jaw. They are small enough to fit on the milling setup.
http://www.ebay.com/itm/like/331114009913?lpid=82&chn=ps&ul_noapp=true
I could probably get away with buying 5C collets only for the few
sizes of ground drill rod I stock. After turning the part on the end
of the rod, usually the only operation on the cutoff end is facing it,
in a 3-jaw.
A 5c spin index lets you index to integer degrees. They aren't my
choice for heavier cuts like milling a hex head on 1" drill rod.
http://www.grizzly.com/products/5-C-Spin-Index/G5649?utm_campaign=zPage&utm_source=grizzly.com
I broach internal hex openings for Allen keys by grinding a smaller
size key to a sharp-edged flat end and mounting it in a boring bar
holder.
The six-sided index attached to the spindle could be a sheetmetal disk
with cutouts that I hold against a block resting on the ways with one
hand while making the cuts with the other. I tried just aligning lines
drawn on the chuck with an index but the work shifted too much diring
the cuts.
My lathe has a threaded spindle that easily holds a homemade indexing
disk (an old car timing degree wheel) behind the chuck or the spindle
nut that pops out the collet adapter.
http://www.homegunsmith.com/archive/T14937.html
First drill the hex recess to the nominal size, the distance across
the wrench flats. Select an Allen key that fits into it and grind it
flat or slightly beveled on the end and mount it in a tool holder with
the flats top and bottom and the cutting corner at center height,
towards you. Feed it in to shave off a thou or so from each of the six
corner, advance outward and repeat until the proper sized key fits.
The tool doesn't cut freely unless slightly angled, and deflects too
much to calculate the total feed distance.
I added the other groups to clutter them up the way they do to us.
--jsw
Bob La Londe
Dec 1, 2016, 1:23:21 PM12/1/16
to
"Jim Wilkins" <murat...@gmail.com> wrote in message
news:o1o8nv$rif$1...@dont-email.me...
try and get people thinking about our craft again now that the political
shit storm has subsided a little.
The flex you talk about to get an angle has the same affect as a 1 degree
angle with a rotary broaching tool.
The idea with the tool post cross drill part is if its left adjusted in a
tool holder I can just drop it in place and drill a cross hole with no
setup. 10 seconds vs 2 minutes or more to take it off and transfer it to
the mill. I've got three parts I have made that require cross drilling and
might wind up being small scale production parts. One would benefit from a
turning operation afterwards. I can mount a collet in the lathe, but I am
leaning towards putting the 4 jaw on and leaving it in place for all the one
off projects.
Actually the mini lathe CNC conversion may get a 3C collet closer and get
used for some of those parts, but the conversion is only half done and
customers just won't pay me unless I promise to make their parts. LOL. I
am leaning towards also CNCing the small lathe with a 3C collet closer as
well.
news:o1o8nv$rif$1...@dont-email.me...
> "Bob La Londe" <no...@none.com99> wrote in message
> I added the other groups to clutter them up the way they do to us.
> --jsw
STOP THAT! LOL. I've been posting metal working questions and projects to
> --jsw
try and get people thinking about our craft again now that the political
shit storm has subsided a little.
The flex you talk about to get an angle has the same affect as a 1 degree
angle with a rotary broaching tool.
The idea with the tool post cross drill part is if its left adjusted in a
tool holder I can just drop it in place and drill a cross hole with no
setup. 10 seconds vs 2 minutes or more to take it off and transfer it to
the mill. I've got three parts I have made that require cross drilling and
might wind up being small scale production parts. One would benefit from a
turning operation afterwards. I can mount a collet in the lathe, but I am
leaning towards putting the 4 jaw on and leaving it in place for all the one
off projects.
Actually the mini lathe CNC conversion may get a 3C collet closer and get
used for some of those parts, but the conversion is only half done and
customers just won't pay me unless I promise to make their parts. LOL. I
am leaning towards also CNCing the small lathe with a 3C collet closer as
well.
Nicodemus
Dec 1, 2016, 4:09:51 PM12/1/16
to
"Jim Wilkins" <murat...@gmail.com> wrote in
news:o1o8nv$rif$1...@dont-email.me:
> I added the other groups to clutter them up the way they do to us.
> --jsw
>
>
>
https://www.mcmaster.com/#broaches/=15a7lve
> --jsw
>
>
>
Jim Wilkins
Dec 1, 2016, 5:01:23 PM12/1/16
to
"Bob La Londe" <no...@none.com99> wrote in message
news:o1ppo8$tlp$1...@dont-email.me...
Mine locks by engaging the back gears but there's detectable play in
the gears and bull pin.
I bought a router motor to mount on the tool post and then realized it
wouldn't handle the range of operations I do to round parts on the
mill, especially cutting large wrench flats, and the setback to allow
for a drill chuck + bit would make the mount too wobbly.
--jsw
Mr. B1ack
Dec 1, 2016, 5:50:31 PM12/1/16
to
On Wed, 30 Nov 2016 23:27:33 -0500, "Jim Wilkins" <murat...@gmail.com>
wrote:
>"Bob La Londe" <no...@none.com99> wrote in message
>news:o1nvqr$dvc$1...@dont-email.me...
>> Now I know the easiest way to do what I want is with a push broach
>> and make them as two pieces, but I want to make some specialty hex
>> drivers with a one piece body. That leaves me with rotary
>> broaching. The thing is I am not going to make a bunch of them so
>> buying a rotary broach holder or spending a day making one isn't all
>> that wise of use of my time or money. However once I was setup to
>> do it rotary broach inserts are a lot cheaper than push broaches.
Hey ! An actual post about METALWORKING from
rec.crafts.metalworking !!! Congratulations on staying
alive despite all this years political posts directed towards
your group (WHY I'm not sure). Feel free to spam the
political groups for awhile with metalworking tips - fair
is fair :-)
And besides, metalworking IS kinda interesting stuff ...
the underpinning of our civilization too ......
wrote:
>"Bob La Londe" <no...@none.com99> wrote in message
>news:o1nvqr$dvc$1...@dont-email.me...
>> Now I know the easiest way to do what I want is with a push broach
>> and make them as two pieces, but I want to make some specialty hex
>> drivers with a one piece body. That leaves me with rotary
>> broaching. The thing is I am not going to make a bunch of them so
>> buying a rotary broach holder or spending a day making one isn't all
>> that wise of use of my time or money. However once I was setup to
>> do it rotary broach inserts are a lot cheaper than push broaches.
rec.crafts.metalworking !!! Congratulations on staying
alive despite all this years political posts directed towards
your group (WHY I'm not sure). Feel free to spam the
political groups for awhile with metalworking tips - fair
is fair :-)
And besides, metalworking IS kinda interesting stuff ...
the underpinning of our civilization too ......
Jim Wilkins
Dec 1, 2016, 6:44:40 PM12/1/16
to
"Mr. B1ack" <now...@nada.net> wrote in message
news:t1a14cptljlf5ssiq...@4ax.com...
It gives us the power to create things with our minds.
news:t1a14cptljlf5ssiq...@4ax.com...
DoN. Nichols
Dec 1, 2016, 10:29:39 PM12/1/16
to
On 2016-12-01, Bob La Londe <no...@none.com99> wrote:
> Now I know the easiest way to do what I want is with a push broach and make
> them as two pieces, but I want to make some specialty hex drivers with a one
> piece body. That leaves me with rotary broaching. The thing is I am not
> going to make a bunch of them so buying a rotary broach holder or spending a
> day making one isn't all that wise of use of my time or money. However once
> I was setup to do it rotary broach inserts are a lot cheaper than push
> broaches.
Yes. Recent experience -- in MSC, a Dumont 1/4" square push broach
> Now I know the easiest way to do what I want is with a push broach and make
> them as two pieces, but I want to make some specialty hex drivers with a one
> piece body. That leaves me with rotary broaching. The thing is I am not
> going to make a bunch of them so buying a rotary broach holder or spending a
> day making one isn't all that wise of use of my time or money. However once
> I was setup to do it rotary broach inserts are a lot cheaper than push
> broaches.
is $101.??, and a 1/4" rotary broach is about $60.00.
> Recently I had need to do some cross drilling that would have been easiest
> with a preset cross drill on the lathe. Its slow and tedious to center up
> and drill the part on the mill, but of course I can do it. I don't have to
> do it often so again making a cross drill for the lathe isn't good use of my
> time.
tool for the purpose? A Morse-taper mounted round pad with a V-groove
across it. Just slap the workpiece (assuming cylindrical) into the V,
and with a drill chuck in the headstock spindle, drill away. I've seen
them in old _How to use a Lathe_ books. Either the Atlas/Craftsman one,
or the South Bend -- if not both.
I would actually like to have one of those myself.
As for centering up on a mill -- the same trick as used for
aligning tailstock and headstock centers can be used. A piece of thin
material -- a 6" pocket scale, or a razor blade, and you can tell which
side is getting the center of the bit by which way the thin piece tilts.
Of course -- another trick which I have read about, but not yet
tried, is to drill the center of the round stock in the lathe with the
size bit desired, then part it off, and when dross-drilling time comes,
put the round stock in a vise with the round parted off part on top.
Use the hole in the parted off piece as a drill bushing to get the bit
truly on center.
> Then I had an aha moment. Make it fairly robust and use it for rotary
> broaching as well. Centering would be a little tedious, but getting my 1
> degree back angle from center would be dead easy to do after that. Then
> lock down all the gibs not in use and advance the carriage. I doubt it
> would ever work on the mini lathe or the small lathe, but maybe the PM1440
> could handle it.
directly to the cross-slide. This eliminates several locations for
play.
> If I can use the same tool for both applications it almost makes it worht
> making one. I might still know where to find it by the next time I need it.
> Driven with hand held drill when cross drilling and of course driven by the
> stock when rotary broaching.
>
> I don't think I've ever cross tapped stock in the lathe, but if I don't see
> why I could not add enough functionality to do that too if I need to.
locked as you are describing it. Or -- if using a variant of the V-pad
in the tailstock, you want a releasing tap holder in the lathe chuck or
collet so you don't tap too deep.
> So what's wrong with it? I know rotary broaching takes a lot of power. The
> lathe is big, but its only 3HP. Flex in the compound, cross slide, and
> carriage could be an issue. If a spacer is used internally in the cross
> dril that rides on a thrust bearing I think the drill itself could take it.
> I also considered bronze bushing with a 1/2 shaft collet chuck because the
> bronze can take so much force.
should get that). However, I just did some broaching in A2 drill rod
using a 1/4 square broach. After making a fixture to hold the drill rod
vertical and setting it up in a 3-ton arbor press (and broaching a hole
which was 3/4" long) I got about half way through before I could not put
enough weight on the lever (my 3-ton does not have the ratcheting lever
arm -- and one of my own arms is still recovering from being broken a
couple of years ago), so I had to move it to the 20-Ton Harbor Freight
Hydraulic press to finish. This with Molybdmium DiSulfide grease as a
lube.
So -- if the rotary broach takes more force, I don't want to
play. :-)
Enjoy,
DoN.
--
Remove oil spill source from e-mail
Email: <BPdnic...@d-and-d.com> | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
DoN. Nichols
Dec 1, 2016, 10:34:42 PM12/1/16
to
On 2016-12-01, Bob La Londe <no...@none.com99> wrote:
> "Jim Wilkins" <murat...@gmail.com> wrote in message
> news:o1o8nv$rif$1...@dont-email.me...
>> "Bob La Londe" <no...@none.com99> wrote in message
>
>> I added the other groups to clutter them up the way they do to us.
>> --jsw
>
> STOP THAT! LOL. I've been posting metal working questions and projects to
> try and get people thinking about our craft again now that the political
> shit storm has subsided a little.
Good for you!
> "Jim Wilkins" <murat...@gmail.com> wrote in message
> news:o1o8nv$rif$1...@dont-email.me...
>> "Bob La Londe" <no...@none.com99> wrote in message
>
>> I added the other groups to clutter them up the way they do to us.
>> --jsw
>
> STOP THAT! LOL. I've been posting metal working questions and projects to
> try and get people thinking about our craft again now that the political
> shit storm has subsided a little.
Mr. B1ack
Dec 1, 2016, 10:34:54 PM12/1/16
to
On Thu, 01 Dec 2016 16:46:41 -0700, Winston_Smith
<inv...@butterfly.net> wrote:
>On Thu, 01 Dec 2016 17:50:23 -0500, Mr. B1ack
>they get unhappy. Seems it's a one way street.
For some weird reason LOTS of "political" posts also
included the metalworking group. I could never find
out WHY ... but kinda felt sorry for them. This wasn't
just the past few months either ... it's gone on for years.
>> And besides, metalworking IS kinda interesting stuff ...
>> the underpinning of our civilization too ......
>
>We prefer to deal with precious metals like brass, lead, and good
>steel.
Maybe they know five good ways to rifle a barrel
without a broach ?
<inv...@butterfly.net> wrote:
>On Thu, 01 Dec 2016 17:50:23 -0500, Mr. B1ack
>
>> Hey ! An actual post about METALWORKING from
>> rec.crafts.metalworking !!! Congratulations on staying
>> alive despite all this years political posts directed towards
>> your group (WHY I'm not sure).
>
>Yuck. Metal stuff in alt.survival. <grin>
>> Hey ! An actual post about METALWORKING from
>> rec.crafts.metalworking !!! Congratulations on staying
>> alive despite all this years political posts directed towards
>> your group (WHY I'm not sure).
>
>
>> Feel free to spam the
>> political groups for awhile with metalworking tips - fair
>> is fair :-)
>
>Years ago I replied to their crossposts with some of our FAQs. Boy did
>> Feel free to spam the
>> political groups for awhile with metalworking tips - fair
>> is fair :-)
>
>they get unhappy. Seems it's a one way street.
For some weird reason LOTS of "political" posts also
included the metalworking group. I could never find
out WHY ... but kinda felt sorry for them. This wasn't
just the past few months either ... it's gone on for years.
>> And besides, metalworking IS kinda interesting stuff ...
>> the underpinning of our civilization too ......
>
>steel.
Maybe they know five good ways to rifle a barrel
without a broach ?
Jim Wilkins
Dec 1, 2016, 11:26:14 PM12/1/16
to
"DoN. Nichols" <BPdnic...@d-and-d.com> wrote in message
news:slrno41qkp.on...@Katana.d-and-d.com...
> ...
without turning the lathe on. I don't like having to swap the hand
holding the work against the vee to reach the power switch on the
headstock while the spindle is running and the drill is in the hole.
Backing out the tailstock could let the work spin. It seems as
dangerous as hand-holding a small part on a drill press.
--jsw
news:slrno41qkp.on...@Katana.d-and-d.com...
> ...
> Hmmm ... for cross drilling -- have you ever seen the tailstock
> tool for the purpose? A Morse-taper mounted round pad with a
> V-groove
> across it. Just slap the workpiece (assuming cylindrical) into the
> V,
> and with a drill chuck in the headstock spindle, drill away. I've
> seen
> them in old _How to use a Lathe_ books. Either the Atlas/Craftsman
> one,
> or the South Bend -- if not both.
>
> I would actually like to have one of those myself.
>
I have one that I never used, so I just went through the motions
> tool for the purpose? A Morse-taper mounted round pad with a
> V-groove
> across it. Just slap the workpiece (assuming cylindrical) into the
> V,
> and with a drill chuck in the headstock spindle, drill away. I've
> seen
> them in old _How to use a Lathe_ books. Either the Atlas/Craftsman
> one,
> or the South Bend -- if not both.
>
> I would actually like to have one of those myself.
>
without turning the lathe on. I don't like having to swap the hand
holding the work against the vee to reach the power switch on the
headstock while the spindle is running and the drill is in the hole.
Backing out the tailstock could let the work spin. It seems as
dangerous as hand-holding a small part on a drill press.
--jsw
DoN. Nichols
Dec 1, 2016, 11:56:41 PM12/1/16
to
relay-switched spindle motor with buttons -- there you just need to add
a NC switch in series with the stop switch.
Jim Wilkins
Dec 2, 2016, 8:01:46 AM12/2/16
to
"DoN. Nichols" <BPdnic...@d-and-d.com> wrote in message
news:slrno41vnb.q0...@Katana.d-and-d.com...
those who don't have other machine tools. It provides only hand layout
and punch mark accuracy lengthwise.
Long ago I cast a white metal bolt-down vee block for my drill press
that served the same function. The drill bit holds the block centered
while tightening the bolts. Before the bit breaks through I raised the
bit and work and turned the work onto the flat tops to give clearance
underneath.
-jsw
Bob La Londe
Dec 2, 2016, 11:07:41 AM12/2/16
to
news:o1q6h1$eh3$1...@dont-email.me...
Yes, I have a foot brake that cuts power to the motor and stops the spindle.
I figured if standing on the foot bar was to much hassle I could add a bar
or catch to it.
> Mine locks by engaging the back gears but there's detectable play in the
> gears and bull pin.
Yeah, mine too.
> I bought a router motor to mount on the tool post and then realized it
> wouldn't handle the range of operations I do to round parts on the mill,
> especially cutting large wrench flats, and the setback to allow for a
> drill chuck + bit would make the mount too wobbly.
Somethings are just easier on the mill. I admit that. My big mill is
actually pretty good inspite of being 35 years old. I do sometimes CNC mill
round parts with it. They usually come out within .0015 of round if I go
modestly slow. Often better Obviously external hexes are easy on the mill.
I even thought about doing a modified internal hex where the flats of the
driven object ride on internal CAM lobes like a lot of the multi size
wrenches we have started seeing in the last couple decades. My issue with
that was that its really really slow to mill out something like that for an
1/4" hex with the necessary 1/16" end mill.
My plan is to use a straight shank ER collet chuck. It goes in bearings or
bushings in a chuck of steel mounted directly in the tool holder. That's a
pretty solid setup. Its used for high speed spindles. I'm so into the idea
now I plan to build a couple of them. (there goes my efficiency) Atleast
one each with bushings and bearings. Any drive connection flex will be a
near non issue as the chuck itself will be right up against its support
bearing rather than suspended out from it. The big issue will always be the
drill bit flex.
I figured if standing on the foot bar was to much hassle I could add a bar
or catch to it.
> Mine locks by engaging the back gears but there's detectable play in the
> gears and bull pin.
> I bought a router motor to mount on the tool post and then realized it
> wouldn't handle the range of operations I do to round parts on the mill,
> especially cutting large wrench flats, and the setback to allow for a
> drill chuck + bit would make the mount too wobbly.
actually pretty good inspite of being 35 years old. I do sometimes CNC mill
round parts with it. They usually come out within .0015 of round if I go
modestly slow. Often better Obviously external hexes are easy on the mill.
I even thought about doing a modified internal hex where the flats of the
driven object ride on internal CAM lobes like a lot of the multi size
wrenches we have started seeing in the last couple decades. My issue with
that was that its really really slow to mill out something like that for an
1/4" hex with the necessary 1/16" end mill.
My plan is to use a straight shank ER collet chuck. It goes in bearings or
bushings in a chuck of steel mounted directly in the tool holder. That's a
pretty solid setup. Its used for high speed spindles. I'm so into the idea
now I plan to build a couple of them. (there goes my efficiency) Atleast
one each with bushings and bearings. Any drive connection flex will be a
near non issue as the chuck itself will be right up against its support
bearing rather than suspended out from it. The big issue will always be the
drill bit flex.
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