Re: Lathe Threading with DeskCNC

>--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Fred Smith" <imserv@v...>
>wrote:
>
> The DeskCNC lathe threading is now released.
>
> The threading is accomplished with a quadrature encoder which is
> electronically geared to the axis drive. This allows precise
> threading even with manual rotation of the spindle.
>
> For pictures and info, please follow this link:
>
> http://www.imsrv.com/cgi-bin/discus/show.cgi?1004/101600
>
> Fred Smith - IMService
> http://www.cadcamcadcam.com/hobby

Fred, Thank you for this link but althouh I understand the setup your
description of the process isn't easy to follow. I have searched for
some more info but can't find anything.

From the link you state:-

Format for threading:

N99999 G33 X9.9999 Z9.9999 P99.9

where N is a optional line number
X is a diametral value. Used to cut tapered threads, normally not used
for straight threads.
Z is the end location of the thread
P is the thread pitch in threads per unit.

For the example above the thread is a 1/2-32, the thread cutting pass is:

N100 Z-.75 P32.0

Multiple passes were programmed with a 30 degree infeed angle long the
back flank of the thread.

The thread was cut multiple times to test the repeatablilty of the
machine and the program. The final cut removed .012 from the diameter
and the thread pitch diameter measured .4747 in.
*********

You say X is a diametrical value used for taper threading but surely X
is the diameter of the work.
In the line N100 Z-.75 P32.0 I'm confused as there is no X value for
diameter or G33 for the threading cycle.

Just as there is no X value I can't see what controls the depth of the
thread unless it's a generic value based on 32 pitch ?

You say "Multiple passes were programmed with a 30 degree infeed
angle" but don't show this. As the info on lathe threading is scarce
could you show a full piece of code from setup to end please.

I can't be the only one confused by this.

"The final cut removed .012 from the diameter" Is this a default
setting ? as on a 32 pitch 12 thou is an excessive cut for a thread
that is only 20 thou deep. Final cut[s] on a thread this size should
be just a couple of thou at the most. Doing this in steel will just
rip the thread up.

I realise it's early days but you have obviously got this working so
you must have a complete program to show the full layout of.

Last question is part of the setup.
"Setup the X axis as either diameter, or radius, and the Z axis as
travel along the bed of the lathe. Enter the steps per inch and accel
curve settings as per the mill instructions. "
Where do we set these ? I'm running version 2.0.1.14 but can't seem to
find these settings.

Thanks.

John S.