A slo-mo crash, with little drama and no damage
Joseph Gwinn
mild steel using the Clausing 5914 Lathe, and had a minor misadventure.
The stock is a 2.5" diameter 12L14 alloy bar held in the 3-jaw chuck. The part
I was working on is 1.000" diameter by 2" long, sticking out to the right where
the 2.5" diameter bar has been turned down. There must have been two pounds of
chips in the pan by then.
Anyway, I'm making a near final pass under relatively slow power feed using a
BXA-16N toolholder, and the flat full face of the carbide insert comes up
against the machined end face of the bar. Instead of machining the face a
little flatter, the whole BXA tool post rotates on the compound, causing the bit
on the BXA-16N to dig a bit deeper. There were no groans or loud noises, but
still this is not a good idea.
Anyway, I realized what was going on, and managed to stop the show before
anything bad happened, leaving only an undercut as evidence.
Another lesson on the way to becoming a machinist.
Joe Gwinn
T.Alan Kraus
I put a piece of ordinary notebook paper under my tool post to provide a
bit of friction. Seems to work.
cheers
T.Alan
Joseph Gwinn
"T.Alan Kraus" <soun...@sonic.net> wrote:
It's a thought. I've heard it suggested before, but don't know how well the
paper will stand up when soaked with soluble-oil coolant.
Joe Gwinn
Bill Martin
How about a piece of fine grit carborundum paper? Something used for wet
sanding..
-bill
F. George McDuffee
<joeg...@comcast.net> wrote:
<snip>
> Instead of machining the face a
>little flatter, the whole BXA tool post rotates on the compound, causing the bit
>on the BXA-16N to dig a bit deeper.
=======
Old time machinists books advises (when possible) setting up a
tool for a lathe cut, that it should be arranged such that if
anything shifts the tool swings out of/away from the cut rather
than into the cut.
Lindsay has many reprints of the older texts that are quite
helpful for the home/hobby machinist.
A good place to start for an overview is
http://www.lindsaybks.com/bks/milne/index.html
and any of these will be helpful
http://www.lindsaybks.com/bks/milne/index.html
and see my web page
http://mcduffee-associates.us/machining/machining_books.htm
Better luck on the next project, and its a mistake only if you
didn't learn anything...
Unka George (George McDuffee)
..............................
The past is a foreign country;
they do things differently there.
L. P. Hartley (1895-1972), British author.
The Go-Between, Prologue (1953).
Gunner Asch
wrote:
>>>>
>>>> Joe Gwinn
>>> I put a piece of ordinary notebook paper under my tool post to provide a
>>> bit of friction. Seems to work.
>>
>> It's a thought. I've heard it suggested before, but don't know how well the
>> paper will stand up when soaked with soluble-oil coolant.
>>
>> Joe Gwinn
>
>How about a piece of fine grit carborundum paper? Something used for wet
>sanding..
>
>-bill
I use a bit of yellow legal pad paper on ALL of my lathes. Works very
well with no damage to anything.
Gunner
"First Law of Leftist Debate
The more you present a leftist with factual evidence
that is counter to his preconceived world view and the
more difficult it becomes for him to refute it without
losing face the chance of him calling you a racist, bigot,
homophobe approaches infinity.
This is despite the thread you are in having not mentioned
race or sexual preference in any way that is relevant to
the subject." Grey Ghost
pyotr filipivich
typed in rec.crafts.metalworking the following:
Paper will stand up well enough. And it is cheap to replace,
while not causing a lot of other problems.
-
pyotr filipivich
We will drink no whiskey before its nine.
It's eight fifty eight. Close enough!
Joseph Gwinn
F. George McDuffee <gmcd...@mcduffee-associates.us> wrote:
> On Tue, 06 Apr 2010 22:47:05 -0400, Joseph Gwinn
> <joeg...@comcast.net> wrote:
> <snip>
> > Instead of machining the face a
> >little flatter, the whole BXA tool post rotates on the compound, causing the
> >bit
> >on the BXA-16N to dig a bit deeper.
> <snip>
> =======
> Old time machinists books advises (when possible) setting up a
> tool for a lathe cut, that it should be arranged such that if
> anything shifts the tool swings out of/away from the cut rather
> than into the cut.
To the extent practical, for sure. But the setup is an Aloris BXA toolpost with
a BXA-16N toolholder held in the left dovetail (and thus perpendicular to the
bedway), cutting up close to the chuck, and the carriage can get only so close
without a collision. There is an irreducible torque arm here.
Another thing to note is that I didn't appear to have the problem when feeding
by hand. The power feed was slow, and so the carbide insert didn't cut when
presented the full face - the rise in force was too slow, so it just shoved the
toolpost gradually aside. If it had dug in and started cutting, the forces and
thus torque on the toolpost would have been lower.
It appears that the problem is common, as is the solution - a piece of paper
under the toolpost, which I will try.
Joe Gwinn
Bob La Londe
news:joegwinn-3D1034...@news.giganews.com...
I use notebook paper for various clamps and fixtures on my mill. It works
great. While I do not soak it down continuously at this time it does get
quite soaked with oil based lubricant. I have not had it fail during a job
or run of jobs where I do not remove the clamp or fixture. Some of the
things I use routinely I have precut several pieces and have them stacked up
in the cabinet next to my mill.