[Noisebridge-discuss] Lathe

[Jesse welz]

On Thu Nov 11 18:23:43 PST 2010, Heiko Panther <heiko.panther at web.de> wrote:

> There is a mini lathe in the workshop, and I'd be interested in using it. I've been told it doesn't work very well. I have a Lathing degree from the Crucible but no
> experience with the mini lathe. Who can tell me more about it?
>
> Heiko

Actually, the mini lathe works quite well for a mini lathe. You just
need to know how to operate it correctly. One thing I have noticed on
all the bad lathing done in Noisebridge is that the cutting tool is in
the wrong position. If you just clamp the cutting tool in the holder
it will be way too low to do a proper cut. I have heard some
horrendous noises coming out of the dirty shop and seen some really
ugly cuts on material that was abandoned around the shop. To get a
proper cut the first thing that must be done is to adjust the cutting
tool height. The cutting tool should be orientated so that if one were
to make an end cut, the final position of the cutting tool should be
directly in the center of the material, leaving the end cut nice and
flush. There should not be a little nipple hanging off the material
when done. The cutting tool should also not be too high. I normally
adjust the carriage (WITHOUT the lathe motor engaged) so the cutting
tool is right up against your bar stock's end. Then; on this
particular lathe, a shim or shims must be used to raise the cutting
tool so that it's cutting edge is aligned with the very center of the
bar stock you are cutting. It would be better to be a little lower
than higher. Try to get it as close as you can to the center. Do a
test cut and check the finish. There should not be a little nub. A
very very small nub is acceptable but try and get it as close as
possible.

I wish we had a Bridgeport type manual mill or a surface grinder or
something to make a really nice one piece, permanent shim but those
would be much too heavy for a floor like NB has. I think perhaps those
lathes are designed to accept a larger cutting tool. Also, make sure
the cutting tool used is sharp. There should be a slight negative rake
on the cutting tool to allow the chips to roll off the material. If
you have never sharpened a cutting tool one should try and find
someone who has to give some pointers on the proper way to do it. It
can be tricky.

I could assist anyone needing assistance with machine tool technology
if they'd like. I used to be a machinist. I didn't run machining
centers very often though so my CNC skills are limited. The CNC mills
I used where proprietary software interfaces that came with the mills.
I am very adept at manual machining though. I almost always come to NB
on Monday nights for circuit hacking mondays and have also been siting
in on Pyclass that same night. If you want to know about things dirty
shop ask me, I love to teach and I'm a total tool geek. Even if you
don't ask and I see someone using a tool improperly or I think you
could use a tool more efficiently I'll most likely come up to you and
teach you the right way in a very friendly and non-condescending way.

Yes, I talk/write a lot.

Best,
Gescykae Wrecca Welz