Need Help!- What causes a stepper motor to jump steps

[erkiwi]

Hi .I have just run a program on my newly finished machine.Halfway through the roughing cut the x axis jumped some steps I then rezeroed the x axis and continued the tool path towards the end the y axis jumped a few steps moving the y 0 about 10mm.The contour finish cut was almost complete when again one of the axis jumped a few steps?Could it be the velocity setting in the motor tuning of Mach 3?
Eric

[jeffs555]

Eric,
Yes, first thing is to try lowering the velocity and acceleration settings. If it still skips steps with very low velocity and acceleration settings, then it is probably some mechanical problem. Backlash can also cause some of the same symptoms as losing steps.

Jeff

[ger21]

It could also be resonance.

[LeeWay]

Sometimes the tested settings work fine when cutting air too, but when you actually engage a part, the cutting forces are higher and the steppers can miss steps. Same goes for different parts in the code. If one particular process puts a lot of force on an axis, then it can miss steps.
The typical fix is to adjust the code slower or tune the motors slower. If you cut and feedrate is optimal for the cutter and the time, you may need to get larger motors, bigger PS or different drivers. Perhaps fine tuning the axis mechanical drives and bearings can also help.

[erkiwi]

Thanks Jeff,I have reduce the velocity by 100 and it did not jump any steps in the roughing cut will try contour milling tonight.thanks.
Eric