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At 11:18 AM 11/5/02 -0700, you wrote:

by hand. Now with the servos the machine is easier to use manually and I
still have not had it grab the work and spin the screw. Makes me wonder how
much of it is armchair musing and how much is actual experience??

Chevailer CNCs with ball screws give you a manual option that completely
disables the drives. And though I said it before, the only grab and slam I
ever had was on a manual machine with Acmes. The cure is always only two
words: table locks.

Regards, Hoyt McKagen

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Well, I just did what I've been telling myself that I have to stop
doing....spend more money on this recent CNC infatuation.

I just scored (2) Triple Stack Slo-Syn Nema 34 550 oz-in steppers for
$60. So now I have (3) double stack Slo-syn motors (370 oz-in) and
the (2) 550 oz.in and multiple size 23s and 17s.

When my Shoptask arrives, I'd like to CNC both the Shoptask and my
Mill/Drill. At this point I wasn't planning to change either to
ballscrew because I'd really like to maintain the manual control of
the machines, thus I know the Z axis of the Mill/Drill could easily
be controlled by any of my Nema 23 steppers. That leaves the 5 Nema
34 motors to drive the other 5 axes of the two machines.

What is typically the preference for which axes get the higher torque
motors? My understanding is that its usually the Z-axis, but because
of the quill feed configuration of the mill/drill, it won't require a
high torque motor. Is the shoptask similar if I don't convert it to
ballscrew? If I put one of the triple stacks on the Z of the
Shoptask, then I'll have to mix up one of the machines X-Y. Would
the X feed on the Shoptask be the best choice for the larger motor
because its also the lathe (Z) direction?

Thanks!
-Chris

On a Shoptask you need the largest motor on the Z axis. The requirements for
X & Y are pretty much the same.

You hear all the yak about not being able to machine manually when you have
ball screws. I have ballscrews on my Shoptask and it machines manually just
fine. I am sure that there are ways to get the machine to pull the table,
but it just has not happened in the limited amount of manual work I have
done. With steppers there is considerable resistance to turning the cranks
and when I had steppers on the machine it was actually a PITA to do anything
by hand. Now with the servos the machine is easier to use manually and I
still have not had it grab the work and spin the screw. Makes me wonder how
much of it is armchair musing and how much is actual experience??

Tim
[Denver, CO]
Sherline Products at Deep Discount
www.KTMarketing.com/Sherline

--- In CAD_CAM_EDM_DRO@y..., "Tim Goldstein" <timg@k...> wrote:

On a Shoptask you need the largest motor on the Z axis. The

requirements for X & Y are pretty much the same. You hear all the yak
about not being able to machine manually when you have ball screws. I
have ballscrews on my Shoptask and it machines manually just fine...

Tim,
I'm sure your right. When I looked at CNC'ing a lathe I was advised
by a ballscrew manufacturer to select low threads per inch if I
wanted to be able to use the lathe under manual operation. Its seems
pretty obvious is a leadsrews pitch was 1 turn/inch it would be hard
to hold. With 10 turns per inch it won't move.

My Tree mill came equipped with handles and 5tpi ballscrews and was
meant to be used either manual (learn and replay) or CNC. It doesn't
move on its own. Ditto on the Z axis.

Roger