could be an oily spindle belt causing spindle slippage and loss of thread pitch start position during cut.
Or spindle encoder, belt or coupling etc;
try the cheaper fixes first.
We have a Integrex 35Y with a T+ control. Machine runs good parts in X and Z but will not cut a thread. The first pass is good but the more passes it takes it starts to wipe out the thread. We check the program and it is OK. No backlash that we can see with an indicator. Could it be the spindle censer??? New machine to us and we have never cut a thread with it.
could be an oily spindle belt causing spindle slippage and loss of thread pitch start position during cut.
Or spindle encoder, belt or coupling etc;
try the cheaper fixes first.
You'll need to check the feedback with a scope. There is a Z phase that should show up only one time per revolution. The Z axis uses this signal to start it's move towards the part for every pass of the thread. If the Z pulse is out of adjustment it can show up several times and this is the problem you will see. You can try replacing the sensor and preamp board. With a new board you should only have to adjust the A and B phases which can be done with a standard multimeter. Make sure it isn't a rotary scale though because those can get expensive and the adjustment is very different.
Is this a "hollow shaft" type of spindle encoder, i.e; a fine gear cut on the spindle shaft with a sensor mounted in close proximity to it ?
Do you have (or can you read) the sensor information and post it please.