Re: [CAD_CAM_EDM_DRO] Lathe software:

It seems like you would do it with a high-resolution encoder. I comes down
to a math and accuracy question. If the finest thread you want to cut is 1
TPI, and your machine is accurate to .001, then the _minimum_ pulses per
rotation you would use would be 1 TPI x 1000 Steps per inch = 1000. Another
example;
12 TPI x .001 = 12000 pulses per rotation.
(The Encoders would require an Index pulse for repeatability.)

Is this how it is done?


----Original Message Follows----
From: dave engvall <dengvall@...>
Reply-To: CAD_CAM_EDM_DRO@egroups.com
To: CAD <CAD_CAM_EDM_DRO@egroups.com>
Subject: [CAD_CAM_EDM_DRO] Lathe software:
Date: Tue, 29 Aug 2000 08:38:41 -0700

This is really all Bill's fault. ( :-))..but obviously there is some
interest in lathe control.

From my point of view there are two approaches to lathe cnc.

1. position of the cutting tool is locked (a slave) to a RATIO of the
spindle speed. That is just like the normal gears on a lathe.

2. position of the cutting tool is a calculated tool path but of course
still driven by an index off the spindle.

One still must do something about spindle index to pick up a thread at
the proper point.

One of the main issues would seem to me to be: at what speed must one
update spindle position to get good cuts.

At 60-70 rpm is takes a REALLY long time for one rotation.
At a couple of thou or better it happens pretty fast....by mechanical
standards. All of this is slow in the electronic realm.

Ideas, comments;
Tnx

Dave




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