Have you got fans and heat sinks on your stepper drives?
My first guess would be your stepper drives are overheating and dropping steps.
Try dropping the motor current if you can't add fans and heat sinks straight away.
When they overheat and shut down it only takes a fraction of a second for them to cool enough to start working again.
It looks just like slipping.
My first guess would be your stepper drives are overheating and dropping steps.
Try dropping the motor current if you can't add fans and heat sinks straight away.
When they overheat and shut down it only takes a fraction of a second for them to cool enough to start working again.
It looks just like slipping.