Multi-start thread?

[DonutSlayer]

I am trying to cut a light knurl pattern in the bore of a part using a threading tool and our Daewoo 400 with Fanuc 21i-TB control, the problem is I have to start and stop the thread tool in a narrow groove, I can do this on our Mori Seiki SL-25 with a Fanuc 15T control with a G76 by using a Q to command what degree the thread starts at, however on our Daewoo 400 Q is a depth command and looking through the books I can't figure how to do a multi-start thread and have the same start point in "Z", any ideas??? These parts are too big to fit in the Mori or I would use it.

[DonutSlayer]

Well, I solved the problem, but it took a call to Daewoo, anyway you have to change a setting called Tape Format so the machine will read a single line G76 cycle instead of the 2 line cycle that's the default, then you can use Q for telling it what degree to start the thread at, and you have to add 3 0's to the number, so for a 4 lead thread you would use Q0, Q90000, Q180000 and Q270000.

[cincron]

This is a bit late....

But I always just use the Z starting point for multi starts... I never liked the Q (personal preference I guess)

if you have a lead on the thread that is .500... and a pitch of .125 this would be a 4 start thread...

I would start the thread Z.200 for the first start and add the Pitch to the next start. the second start would be Z.375, the third is Z.500 and the Fourth I would start at .625.

You would still feed in on the lead of the thread... which in this example it would be .500...

Either you way or this example would work... some would have to use this example, if the control will not allow the "Q" for the starting C position...