Machsupport Forum

General CNC Chat => Building or Buying a Wood routing table.. Beginnners guide.. => Topic started by: derd83 on September 19, 2015, 04:28:12 PM

Title: z axis missing steps
Post by: derd83 on September 19, 2015, 04:28:12 PM

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?

Title: Re: z axis missing steps
Post by: RICH on September 19, 2015, 08:06:39 PM

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

RICH

Title: Re: z axis missing steps
Post by: derd83 on September 20, 2015, 04:17:57 PM

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?

Title: Re: z axis missing steps
Post by: RICH on September 20, 2015, 10:21:15 PM

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