[CC12v]

Spindle runs higher than programmed by 15- 25 rpm's.I also have a problem with rigid tapping. It seems the spindle and the feed is not sync'd. After a few threading cycles the tap starts pulling out of the collet,the threads don't look clean.
I assume this is a parameter issue ? Machine was bought used over a year ago.Other than that machine is in fine operating condition.

[CC12v]

Any ideas where to start looking to fix this?

[fordav11]

are you sure your machine has rigid tapping option?

[CC12v]

Where would I look to find out? I bought this machine used.

[angelw]

Where would I look to find out? I bought this machine used.

As you're talking rigid tapping, does your machine have live tooling? Although rigid tapping with the main spindle is an available option, not too many machines are supplied with it.

If the machine does not have live tooling and you're trying to rigid tap with the main spindle, one method of determining if rigid tapping is available is to execute M19 via MDI. If the main spindle orientates to a position and stops, then its a good chance that rigid tapping is available.

Regards,

Bill

[CC12v]

It goes through the motions. Feed in, reverse spindle feed out. It will tap. Its just obviously the timing is off. If you program X amount of feed at X amount of rpm your threads will not be clean if your machine runs more rpm than programmed.

[fordav11]

the timing IS what the rigid tapping does. any lathe will go through the motions but without the rigid tapping option the timing will be off......

so, have you got live tools and does M19 work?

there may be a spindle RPM calibration adjustment in the spindle drive unit. you'll need to check your maintenance manual.

[angelw]

It goes through the motions. Feed in, reverse spindle feed out. It will tap. Its just obviously the timing is off. If you program X amount of feed at X amount of rpm your threads will not be clean if your machine runs more rpm than programmed.

How did you determine that the spindle speed is out by 15- 25 rpm, was it checked with a tachometer?

If the feed is not synchronized with the spindle speed when using a rigidly held tap, then yes, the thread will not be machined correctly. However, if a tap holder that has axial extension and compression is used, then within reason, slight out of synchronization will not adversely impact on the thread. You haven't confirmed if your machine actually has Rigid Tapping. If it hasn't, and you're using a rigidly held tap, then for sure a less than perfect thread will result.

Regards,

Bill

[CC12v]

Machine does not recognize M19. No rigid tap.Guess I'll use a tap holder.
So what is the cause of the difference in programmed rpm and actual running rpm. If program calls for 1000 rpm's,the screen reads 1015 ish ?
When using the manual spindle controls , if I roll the speed knob to minimum, the spindle will bounce back and forth like it doesn't know what to do.Roll knob up a bit and she will start to turn at a constant speed.