Developments on my Home built 5C CNC Lathe - Polar interp. and Live tooling

spumco wrote:

There is still an issue with threading in LCNC - thread start point varies with RPM - but that's not related to caxis.comp.

Yes, it's probably best to turn off CSS when threading. 

andypugh wrote:

Yes, it's probably best to turn off CSS when threading. 

Andy,

I wasn't using CSS when threading.  Multiple attempts at tapping the same thread at different speeds resulted in different start points.

What I discovered (through @Aciera's help) was that caxis.comp interfered with threading/tapping, and that LCNC has a bug in G33.1 and G76.

forum.linuxcnc.org/38-general-linuxcnc-q...peed?start=30#317931

Yes, this definitely seems like a bug.

I can see the cut starting at a different place at different spindle
speeds due to the time needed to get synched to the spindle
varying at different spindle speeds, _but_ once synced and cutting,
the threads should be identical regardless of spindle speed...

(as they are in a normal manual lathe than maintains strict gearing
between the spindle angular position and Z offset)