Re: [CAD_CAM_EDM_DRO] EMC Lathe mode.

Art Fenerty wrote:

>
> I seem to be hearing from a few people lately who would
> like to see lathe capability added to my software. Since
> it is based very much on the EMC code kernel, I thought
> I'd ask the EMC guru's what would be required to add lathe
> capability.

No big deal for the basic lathe operation. The machine tool
itself doesn't even know it is a lathe!

The Z axis is parallel to the spindle/chuck (as always).
-Z goes toward the chuck ( usually left)
+Z goes away from the chuck (usually right)

The X axis goes perpendicular to the chuck center line
+X goes away (usually up and back on a CNC lathe, opposite
to a manual lathe where the tool is in front)
-X goes toward the centerline

> I have never used a lathe CNC before, what is necessary?

In its most basic, just X & Z
Next, spindle on/off and limit sensing (coolant control, etc)
Further, spindle rpm sensing is nice.
Most CNC lathes have one or more turrets, so to change tools,
the turret motor needs to be controlled.

>what would be nice?

Not only spindle rpm sensing, but also exact spindle position,
requiring an index pulse once per rev. You'd need this for threading.

Lastly, it is ultimately desirable to control the spindle speed
directly from the PC under program control. That way you can
optimize cutting by controlling the speed of the surface cutting.

As a super-bonus, going in with a digitizer to determine your
exact cut (and hence re-set the tool dia & tool length offset
in your tool table), and diving in one last time for that
'perfect cut' would be neat.

Thats pretty much it. In summary, if you don't need threading,
just your standard gcode interpreter running in 2 axis mode
should work.

Doug Fortune
http://www.cncKITS.com