I am cutting 20mm dog holes in my spoilboard slats. I placed 1/4" MFD under the 3/4" slats as a secondary spoilboard. I set the material thickness to 19.050mm and added 0.5mm to the pockets. This worked well to cut through the first 4 slats. Then on the 5th and 6th slat the Z axis seemed to have jumped “up”. The pockets were only cut to about 14.5mm and the first several passes of each hole were cutting air. I paused, stopped and re-zeroed the Z. I disabled the already cut tool-paths and started with the slat 5 again. It cut fine for three more slats then jumped the other way. The Z axis was not raised high enough to clear the slats and carved shallow grooves across two of them. Again I stopped, re-zeroed and restarted to successfully finish
Why would my Z axis just go wacky? It can’t be a slipping belt. My VFD is clammped in tightly. I verified the tool-path definitions and they are all using the same thickness, etc.
Whenever i’ve had slippage on the Pro 5, it’s been due to physical binding causing things to slip or loose screws on the axises. There is a guide available to show you what all screws to check/tighten. The motors that drive the ball screws, those connectors can get lose and spin in the mount, there is only the little allen set screws holding it against the shaft (which is keyed).
Could the tool be slipping down in the collet? Happened to me once. I thought I had the end mill secure in the collet, but it wasn’t tight enough and slipped down about .250" over the course of the job. Ruined the entire project.
Do you have a link to the guide on what to check? I don’t think I’ve seen an official one, and I spent a couple weeks chasing down issues when I first got my (early after release) SO5.
I really with C3D would provide torque values for literally everything.
I was not watching the CNC closely when the first problem occured. It is possible that the body of sweepy ran into the vacuum hose. I just had it laying on the bench in front of the machine. When the second Z jump occurred I was watching. It acted just like I purposefully did not raise the bit high enough.
As to a loose collet or bolts holding the spindle: I don’t think so. The collet was quite tight when I took the bit out. The spindle had not moved relative to the parts it is mounted too. Perhaps the stepper motors slipped, perhaps due to stress from a collision with something.
I took some time off to build a frame above the bench to hold a “curtain rod” with hangers to support a vacuum hose. I used the Rockler Flexport hose which expands and contracts well. Now there is not likely to be any collisions.
I have resurfaced my spoilboard and run a couple other small projects with no more issues.
Thanks to everyone for suggestions of things to watch.
I’m going to suggest a simple test. With the machine off, remove your z motor(4x 4mm bolts up top) and then try raising and lowering your z-axis plate. I found multiple causes of binding on my z-axis. It took easily 15lbs of force to move my Z before making several adjustments. There are still patches of difficulty due to poor quality ballscrew&ballnut, but now the z can drop on its own with the motor removed. These steppers are plenty strong to move a 12lb spindle, but they will skip steps if there’s enough resistance. Intermittent missed steps will ruin your project and-or day.