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Stepper motor missing steps? Answered

I'm running a CNC machine using Mach3.
After running some GCode, a stepper motor appears to have missed some steps.
The Z-axis has shifted (a reference point has changed coordinates.)
No apparent visible changes, so I assume the stepper has skipped.
What can I do?

4 Replies

steveastrouk (author)2014-06-23

Run the Z axis backwards and forwards, and check to see if it misses steps with your current setup. That can be because of acceleration, but more likely because of too much load and/or friction on the axis, making the axis skip a step.

That's why real CNC machines ALWAYS have position feedback from the moving parts.

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rickharris (author)2014-06-23

1. Check for mechanical restriction

2. Check PSU is providing the current your stepper motors require.

3. Check by moving to several different points and making a small mark - repeat to see if the marks drift.

4. If you can see the altered coordinate in the Gcode then something serious has happened and you need to talk to the software suppliers.

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liquidhandwash (author)2014-06-21

I had the same problem, the acceleration was too fast, took me all day to work it out.

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mpilchfamily (author)2014-06-21

Need to recalibrate or pull the axis apart and see if there is any damage to it. May not be the motor.

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