Hi Guys
Not been here for a while . Do please excuse me

So I have been progressively converting My Boxford TCL125, initially to Mach 3, then further to linuxcnc to try and get me a screwcutting capability.
I do have it working , But it just will not execute a G76 instruction for a threading canned cycle
I am using Gmocappy on linux mint. Hal and Post hal gui files have been edited to make the speed indicator and tool change functions work.
All the traverses function in slow and fast jog and the machine is happy to execute a turning routine in both G94 and G95 with feeds of up to 2mm/rev as an exercise (have not tried higher ) Cant imagine I would need bigger pitches on this machie .

Initially I did have problems with the pulses from the sensors but these were upgraded and I am now happy they are reliable . They give clear indications in “Hal show configuration” and steady speed reading on the gmocappy screen. I had wondered if the Boxford index disc with 100 x 2mm holes was too fine so tried with a disc I made myself with 48x 4mm holes but this is no different.

I can run with this disc in mach3 and using pin 12 (single notch) , I see a speed of about 1150 revs .
Changing index in Mach3 to pin 13 it reads a speed of 55k which seems as near to 48/1 as I can reasonably expect. And the readings are pretty steady so I am not suspecting noise as the problem.
Linux was initially sluggish on the machine I was using, slow to boot , slow internet, etc so moved the HDD to another machine . It is now quick and responsive but still won’t execute G76.

Code here!

Goes through to line 11 quite happily executing tool change on the way but then refuses at G76.
No error message just sits there.
%
(Thread M10 x 1.5)
(CHANGE TO T6 ON Front TOOL POST)
M6 T06 G43
G54 G90 G94 G18
G21 G80 G95
G90 G7
M08
F1.5 S350
M3
G4 P5
G0 X10 Z10
G76 P1.5 Z-12.5 I-0.001 J0.1 R1.0 K1.5 Q0 H3 L0
G00 X45
G00 Z30
M09
M5
M30
%

Have tried different spindle speeds from 100 to 600 but no change.

I am not quite ready to jump out of my tenth floor window yet but it is rapidly coming to that stage
Can anyone shed any light on what we might be missing or where the fault may lie
TIA John