Re: Asian Lathe Conversion

Roger:

Well, I guess I don't blow my own horn much then. TurboCNC has had
G33 closed loop threading suppport since April of last year. Works
well for me, and the handful of users bold enough to try it on their
own machines as well.

To save this post from being completely gratuitous self promotion:

The algorithm for closed loop threading motion is quite simple and
for the two other programs you mentioned, it shouldn't be hard for
their author(s) to add since they are both, AFAIK, velocity based
controls.

- Obtain the spindle velocity.
- Start moving when the index pulse passes.
- Use a digital adaptive filter to come as close as possible to the
ideal position in time for the next pulse to arrive, at which point
the velocities are updated.
- Until the move runs out of distance, and then the regular ramp-
down takes over.

Naturally there need to be a handful of safety checks, but that's
really all there is to it. Another axis for a tapered thread is just
another variable in an array. Multi-start is just using an offset
start position, and variable lead (not supported) would merely add a
constant coefficient to the filter.

Dave Kowalczyk
Everett WA
Author of TurboCNC -->http://www.dakeng.com/turbo.html

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "vrsculptor
<vrsculptor@h...>" <vrsculptor@h...> wrote:

>
> Bummer for me is that PC cnc programs (EMC or my favorite Mach1)
> don't handle threading. This shouldn't be a problem for you.
>
> Roger