Re: [CAD_CAM_EDM_DRO] Thread milling

Drew Rogge wrote:

> There was a discussion a while ago about thread milling but after
> talking my cousin into trying it on his CNC machine I realized
> that I don't know if there's a straight forward way of doing it.
> I first thought that all there was to it was to do a couple of
> circular interpolations in XY while ramping down in the Z. Now
> I'm wondering how one programs the arcs with G02/3 while ramping
> the Z with a G01. Is there an easy way to do this or do you have
> to approximate the arcs with a bunch of short lines?

With modal command G17 (arcs interpolated in the XY plane)
then any arc commands only cause circular motion in the X and Y
axes, and the Z axis is still linear. You do not specify a G01 for Z.
With G17 in force, and movement specified by a G02 X... Y... Z...
(and some I, J or R word to program the radius), you will get
a helical motion around the Z axis. This will get your thread milled
with an appropriate cutter.

You do NOT make short linear segments, just one command for every
1/2 or 1/4 revolution, depending on some details of your CNC control.

Jon