Hi,

I'm trying to cut metric thread on my Denford Starturn lathe using Mach4 and a Pokeys57 card. I only use a index pulse which seems to be stable and accurate. I believe the Pokeys configurations is set-up correctly.

I've used the Mach4 Turn Cycles conversational programming to generate the code, using the 2-line G76 command.
In this attached file I tried to achieve a pitch of 2mm but I have tried various larger pitch sizes, thread depth is set at 0.25 mm. The actual RPM was around 480.

The process seems to be correct but the depth of cut is wrong and the cut pitch is always around 0.6 mm, irrespective of my pitch setting.

What am I doing wrong? Thank you very much

Danie
 

Steps per unit wrong ? Or the number of pulse for the RPM is not correct. You have a meter to check the RPM ?

Change your code to read :-

N92 G97 S250 M3
N95 G00 X6. Z10.  (Rapid move to Clearance Height)
N100 G76 P020060 Q0.1 R0.04 K1
N105 G76 X4.5 Z-10.0 R0.0 P0.25 Q0.1 F2.0
N110 G80

Hi,

Thank you for your feedback. I will make the code change.
 I also found an error in X gain and the Z vel was set too low for the required pitch.

Regards
Danie

Graham, I didn't even think to look at the code. Guess I should learn to read it