Zero of Z axis changes with Fusion360

[CHM]

Hi everyone.
I have a problem with the zero point of the z axis changing with F360 output.
I zero XY and Z run the fusion .nc file and sometimes the cut will be in the air and sometimes it will dive straight into the bed. Sometimes it cuts fine.
If I re zero Z after the file has run it cuts fine. X and Y are not affected.
It would be easier to track if it happened to every file!

UC300ETH . Stepper / ballscrew driven home built CNC

Very, very happy with UCCNC!

Thanks, Charles

[cncdrive]

If the Z axis zero point is changing means that your stepper motor is loosing steps.
This means that maybe the stepper drive has a problem, or the motor has a problem or the mechanics has a resonance which causing it.
It is also possible that you set too high kernel frequency in the UCCNC which your stepper drive cannot read properly.
Try to set a lower kernel frequency in the UCCNC general settings and also check the step/dir wiring and motor wiring and the mechanics.

[Battwell]

also check your fusion job setup.
its easy to have the wrong fixture number set for different jobs.
g54 to g59

i removed the fixture from my fusion post processor.

[CHM]

Hi,

Thanks for your thoughts on my problem.
I'm pretty sure that my Z axis / stepper setup is solid. The Z axis zero changes by about 30mm

I will look into the Fusion post processor.

Thanks again,

Charles.

[AkaMrBill]

I am experiencing a very similar situation.
The Z axis on my Stepcraft D840 is rock solid.
My issue happens when I process multiple tool paths together, when using the same tool.
It exhibits as, at the beginning of the second or third path, the Z axis will rapidly dive through the stock material and into my waste board to about .25" below the stock then continue the path at that depth.
This has never happened if I run paths one by one.

I am using F360, UCCNC on the Stepcraft.