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

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

Bad thread form Tooling and work holding Encoder pulley and belt problems Defective encoder Encoder cable Bad axis motor or MC2 motion control card Mechanical problem	Servo shut down during threading Programming problems Axis over travel - Check stroke of slide
Slide goes into position and won't thread Spindle encoder Encoder cable	Bad Finish Tooling and work holding Programming problems
First thread is bad Programming issues	Threading cycle has to many passes Check the "I" value, it could be to small

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.

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2. 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.

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3. Encoder pulley and belt problems

A mistracking 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 pullies 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.

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

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4. 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.

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5. 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.

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6. 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.

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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.