I have been trying to cut a thread,and have had problems with the spindle not in sync. with the axis movement.

Not one pass is in the same path with another.

Is there a parameter that will make the spindle and the axis run together in sync.

You have to have an encoder on the final spindle shaft for the threading operation to work. If you do have an encoder, then it could be backlash that is the problem.
What G code are you using to thread?
Al.

The machine that has problem is a 1995 Daewoo Puma 8S with a Fanuc OT-C control,I think it should have this encoder. Here is the program that I'am using


(TOOL - 8 OFFSET - 8)
(LTHREAD OD THREAD RIGHT INSERT - NONE)
G0X0.Z0.
G0T0808
G97S200M03
G0X-.085Z.6347
G76P010029Q.001R0.
G76X-.49Z-1.02P1025Q127R0.F.236
G0X0.Z0.T0800
M05
M30
%

did you try doing it in metric

Do you think that it would make a differance,I hope it will.
I'am using master cam 9,is there a spot where I can change it to metric.

How did you make out? BTW how much is the sync off by? is it a few thou of to one side or the other? or is it off by as much as 1/2 a thread for e.g.?
does it accumulate?
Al.

What size thread are you cutting?

Well the thread is all over the place.I look at the screen and the rpm is not shown,checked the parameters and they seem right so went on to remove the encoder and found that the LED on the photo sensor is not lit,checked with a meter and there is power so I think that the encoder is bad.
What do you think.

It looks like the problem, what you may be getting is the 1 pulse/rev that triggers the sync start but not getting the main A/B pulses correctly. Especially not seeing the rpm on the screen.
Al.

Do you know where I can get encoder A86L-0027-0001 #002
Will the machine run with out this

Apart from Fanuc themselves there are not many options apart from ebay etc, in Canada you could try North American Industrial in Mississauga (905) 565-6166,(also in Quebec).
They may be a better price than Fanuc.
The machine will run without it, but functions that use the encoder like constant surface feed and threading etc will not work.
If you want to get creative, find out the counts/rev and replace with a cheaper encoder, the plug would have to be changed, however.
Al.

The spindle encoder channels A & B and the complimentry signals are used for inches per rev only.
The Z and not Z pulse occurs once per revolution and signals the axis move to sync in threading mode.

Make sure the start point of the threading pass is far enough away form the part in order to see the sync pulse. There is a formula for the start position depending on the thread pitch.

Regards Dave