Hello all,

My Denford Orac has threaded with G76 many times without failing, but is now
stuttering in the Z axis. It stutters from Z6 to Z-22, comes out in X ok, but then struggles to return to Z6
again for the next pass. It then thinks it is at Z6, according to the Z axis DRO on mach screen. So with each attempted pass
it is getting closer to the chuck each time.

Works fine if I untick "use spindle feedback in sync modes", so Z mechanically good, but threads obviously ropey.
General turning is good and Z repeats very well.

Old pc died, so using the pc (Dell GX270) that I normally use for my Denford Triac
I'm sure I copied the Mach3 folder from the old pc (Dell GX260) to this one ok with my usb stick.

I'm using ver 040, but not 100% this is what I had on old pc.
I can't find other versions on Artsoft website to download and try.
I copied my original licence from my email into the mach3 folder just to make sure.
I don't know how to paste my latest xml file onto here.

I've cleaned the opto sensors and LED on board works for each rev when I rotate by hand.
Debounce set to 0, I've tried other values with only a slight difference.
Spindle speed averaging ticked.
I soldered onto pin 12 from 13 and changed Index to pin 12 and no difference.

Here's my G code:

G18 G40 G49 G90 G94 G80 G55
M03 S350
G04 P5
T0202
G00  X27.5 (M27 THREAD)
G00 Z6
G00 X27
G76 X25.16 Z-22 Q2 P1.5 J0.1 L45 H0.5 I29 C0.5 B0.05 T0
G0 Z20
G0 X40
M5
M30

I can only think it is either the pc, noise, version of Mach or faulty opto sensors.
Waiting to get another pc.


Any help would be much appreciated,

Thanks,
John

Problem solved, G97!

Excellent 

Tweakie.