ENC-0005: 1000-LINE; 3/8" HOLE SERVO TURRET/COOLANT NOZZLE POSITIONING. EMAIL FOR LEAD TIME.

How to Check Your Fadal VMC Spindle Encoder

Here is a simple, step-by-step guide to checking if your Fadal VMC encoder is working correctly.

A key sign that an encoder is starting to fail is when you see the spindle RPM surge up and down and the load meter spike. This happens because the encoder is sending a bad signal to the machine control.

The best way to test the encoder is with a tool called an oscilloscope, which lets you see the electrical signals. A simple voltmeter can't show you all the details you need to know.

What the Encoder Does

The encoder sends three signals to the Fadal control:

• Channels A and B: These two signals tell the control how fast and in what direction the spindle is spinning.
• Index Pulse (Z Channel): This is a single signal that tells the control when the spindle has completed one full turn.

The Best Way to Test (Using an Oscilloscope)

1. Turn off the machine. Unplug the encoder's cable.
2. Connect the oscilloscope to the wires for Channels A and B.
3. Slowly turn the spindle by hand.
4. Look at the screen. You should see two clean, even square waves that look a little out of sync with each other. The voltage should be a steady 0V to 5V.

If you see no signal, the encoder is likely broken or has no power.

If the signals are messy or jumpy, the encoder is probably misaligned or damaged.

If the signals aren't properly "out of sync," the machine will get confused about the direction of rotation.

A Basic Test (Using a Voltmeter)

This method can tell you if the encoder is completely dead, but not if it has a smaller problem.

1. Turn off the machine.
2. Connect your voltmeter to the encoder's power wires to make sure it's getting 5V.
3. Connect the voltmeter to the signal wires for Channels A and B.
4. Slowly turn the spindle by hand. You should see the voltage go up and down. If you see no change, the encoder is likely broken.

Using the Fadal Machine's Own Tools

You can also use the Fadal control to help diagnose a problem:

• Check for alarms. Look for any alarms related to the spindle's speed or position.
• Try Spindle Orientation. In the MDI screen, run the command M19. If the spindle doesn't lock into position consistently, the encoder is probably the problem.
• Swap it out. If you have another encoder on a different axis that is the same part, you can temporarily swap them. If the problem moves with the encoder, you've found the issue.