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Author Topic: Problems with Z not cutting the right depth  (Read 1236 times)

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Problems with Z not cutting the right depth
« on: January 24, 2017, 09:18:17 PM »
I'm using Mach3 ***.056 and have been for some time. I'm building a Joe's EVO CNC and now I've found a new problem. I thought I had been through most of the glitches. I'm trying to make a plaque that I've made about 50 times before on my old Blacktoe CNC router.
For some unknown reason the Z axis is not cutting to the right depth when the g-code calls for a depth change. The code says to cut to 0.045 below zero but the tool (a 90 deg v-bit) barley scratches the surface of the wood. The Z DRO shows the depth change but for some reason the stepper is not moving to the right depth. I have re-calibrated the stepper so many time I've lost count. I use the auto calibrate and move Z down 4" to set the steps. When I recheck the movement of Z it is almost perfect. But this is not reflected when I try to run g-code.
Question: could this be noise in my system?  ??? Or is there a setting I'm missing?  ???
I'm using a Chinese spindle and VFD which has been the source if most of my problems because of the RF noise. I have shielded wire on the spindle but I don't think the shield is grounded very well. So tomorrow I will do a better job of grounding the shield.
Re: Problems with Z not cutting the right depth
« Reply #1 on: January 25, 2017, 08:34:30 AM »
This morning I connected the shielding in the output wire from the VFD to the spindle.   :D :D ;D ;D
Looks like the shielding has to be grounded on these Chinese spindle-VFD. And some advice: NO ground wire from the spindle motor to ground.
The noise output from these Chinese spindle-VFD is significant.  Caused all kinds of problems while running G-Code even though the gantry would jog up & down the table smooth as silk.

Offline Tweakie.CNC

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Re: Problems with Z not cutting the right depth
« Reply #2 on: January 25, 2017, 09:57:30 AM »
Quote
The Z DRO shows the depth change but for some reason the stepper is not moving to the right depth.

Perhaps a mechanical problem with your machine (loose grub screw, slipping coupling, etc.) or an electrical problem (Z axis motor, motor driver, wiring connections, etc.).

Tweakie.
KEEP SAFE !
Re: Problems with Z not cutting the right depth
« Reply #3 on: January 25, 2017, 10:11:00 AM »
Hi Tweakie,
I'm sure my problems was noise coming from the spindle. I ran some g-code without any difficulty. :) Let's hope that this is the last of the glitches with this CNC router.