Re: [CAD_CAM_EDM_DRO] Inertia calc

Ozzie@... wrote:

> I want to use a servo motor and a Gecko Drive to turn the lathe
> spindle of my Shoptask, not as a permenant setup but as an
> alternative drive when I want to cut threads using CNC. I have a 60
> volt, 7.2 amp, 34 frame, 2300 rpm motor. (Very heavy piece of iron).
> My question is:
> If I use 10 to 1 timing belt pulleys, will this motor produce enough
> starting and stopping torque to accomplish my purpose.

Most likely it will work for modest jobs. It might even handle
threading of hard materials with coarse threads, where a lot of
torque is required. Of course, you'll still need an encoder on the
spindle.

> Or as an
> alternative should I rig a worm and worm gear drive. This of course
> would be a much more difficult job.
> I don't know the weight of the spindle assembly, but 20 pounds or
> less would be a guess, and I wouldn't be using a heavy chuck, just a
> collet closer. Spindle speed could be in the 50 to 200 rpm area.

Well, this is a bit of a problem. At 50 RPM, with a 10:1 belt reduction,
the motor is only turning 500 RPM, or less than 1/4 of rated speed.
This means you lose a lot of power. The torque will be fine, however.

I don't know why you are worried about starting and stopping torque,
as the spindle does not need to stop and start for threading. The spindle
can be run continuously, while the tool plunges in, feeds toward the
headstock and then pulls out at the end of the thread and returns to
the starting point.

Jon