Colchester 3000L Bar puller problem, program stops after M78/M79

Hi All,

Long time lurker, first time poster here.

We recently acquired a Colchester 3000L CNC Lathe with Fanuc OT control.

Amazingly, everything is working just fine with the exception of bar puller work. The programme just stops after either an M78 or M79 when in auto run mode, my program is as follows (we are using a 'crocodile' style puller):

T0404
G00X20Z-14.6
G94G01X-10F500
M78
#HAVE TO PRESS CYCLE START HERE#
G04U2.0
G01W10
M79
#HAVE TO PRESS CYCLE START HERE#
G04U2.0
G01X20
G00X200Z200

I have tried M31/M32 to 'ignore' the spindle interlock function but the program just freezes when it tries to run the codes (I assume it doesn't recognize them).

Can anyone point me in the right direction?

The book clearly states that M78/M79 are for opening and closing the chuck for bar feed/bar pull work.

Any help much appreciated, also I am missing the Fanuc OT Operators Manual if anybody has a spare copy!

Thanks all, John

Google Fanuc OT.pdf

Does it actually open the chuck then stop? I'd guess you have proximity switches on the actuator you need to adjust, or some machines use a hydraulic pressure switch.

Sent from my G-Tab Quantum using Tapatalk

Thanks all for the replies, we have diagnosed the 'chuck closed' sensor is dead, so we are working on replacing that, will feedback soon if that solves the issue.

Currently have a guy pushing the button each time!

For anyone who experienced this problem, it was a pressure check within the chuck open/close cycle that caused the issue. Once we wound on the pressure a bit this functioned perfectly!