40 Allen Boulevard
Farmingdale, NY 11735
Tel: (631) 694-9400

Threading Problems


There are several things that can cause threading problems on the OmniTurn.

Here is a list of problems and what can cause them.

  1. Tooling and work holding:
  • Check your tooling to make sure the insert and tool holder are tight and the center height is right.
  • Also check that the part is not slipping in the collet.
  1. Programming problems
  • Tool dragging across finished thread. This is usually cause by the “I” value being too small or the starting point to deep.
  • Z-axis servo alarms out when starting thread. This indicates that the K value in the G33 mode is too high or the spindle speed is exceeding 300 inches per minute.
  • If the first thread is bad the starting position in Z maybe to close.
  • Changing spindle speed while starting the threading cycle. Make sure you have a constant speed before you start threading.
  1. Encoder pulley and belt problems

A mis-tracking spindle encoder belt can cause a number of problems that yield bad thread forms. Or the thread is stripped off the diameter.

  • Make sure that the belt is tracking properly on the pulleys.
  • The belt should be taught but not over tightened. If a belt is to tight, the encoder will not read correctly.
  • Check the belt for imbedded chips and wear.
  • Make sure the encoder pulleys are not slipping on either side, spindle or encoder.
  • Check to make sure pulley hub has not broken away from the main pulley.
  • Also check the spindle adapter, and make sure pulley has not broken away from it.


Run test procedure as follows.

Encoder pulley and belt test

  • Ø Mark the both pulleys at 12 o’clock with a grease pencil or caulk.
  • Ø Mark the spindle at twelve o’clock.
  • Ø Run the spindle for a while (30 seconds). Stop the spindle and turn by hand back to twelve o’clock
  • Ø Timing marks should be back to the original alignment.


Correct    Incorrect
 good%20marked%20pullies  pullies%20marked%20not%20good


  1. Defective encoder:
  • The spindle encoder tracks inches per revolutions. When a spindle encoder fails the OmniTurn will no longer feed in (G95) the inches per minute mode or it can feed erratically. This will result in a bad lead.
  • The encoder is not seeing the Z marker pulse if the tool goes to its starting position before the thread and stops. This could also be the cable causing this problem, check it next.
  1. Encoder cable:
  • With the control off remove the encoder cable and look at the pins on the connectors. Make sure that they are not pushed back inside the connector.
  • Look at the female connector on the control.
  • Check the cable for cuts, tears and other possible damage.

If you suspect there may be a problem with the cable, and you have another OmniTurn swap cables.

  1. Bad Servo motors or bad MC2 card:
  • Run the Ctrl-H/Ctrl-C test to determine if there is a problem with the motors or if it is mechanical.


Mechanical Problems:

  • If the thread is still not tracking right and you notice that dimensions on your work piece are also varying, check the drive couplings between the ball screw and motor.
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40 Allen Blvd. Farmingdale, New York 11735
Tel: (631) 694-9400 | Fax: (631) 694-9415 |