Greetings all,

I'm having trouble with my homebuilt CNC. It can do 2.5D fine, but when it comes to 3D stuff it all goes wrong. I've been testing out the z-axis, and it seems to be losing steps. Strange thing is, on a run of 50 cycles of Z0-Z50-Z0 it is about 19mm low every time. I have run setup to change the steps per, checked the couplings, halved the acceleration, changed kernel speed from 35k to 25k, tried running the cycle at 100mm/min and 800mm/min, and it is still out by about 19mm EVERY. SINGLE. TIME. I'm confused, if it was simply losing steps surely the likelihood of it being reliably out of whack is minimal?

Any suggestions?

Do a calibration check of the Z axis as the step per may be off.

RICH

I tried that, no luck... I have discovered through much tinkering that the steps are being lost when raising the gantry. When lowering it, it's pretty much spot on. Maybe the gantry is too heavy for the motor?

Could be.
Try changing the velocity and acceleration and see what happens. The motor  torque decreases with increase of motor rpm.
Can also try a using a different gearing ratio.


RICH