Vcarving Trouble

I am losing steps in Z when V carving small parts, about 5"x5". I changed the VR settings to try and fix the problem. The toolpath runs smoother but it still misses steps. I attached a dial indicator to the router and ran the program and its about 0.120" above the part. I tried different speeds, from .5 to 2 in per second, and I matched the plunge and cut speed in Artcam as people suggest. I have looked thru many post and have modified my speeds and values to reflect there suggestions. Lots of good advice but I can't fix the issue.

I have checked the machine for play and it all seems fine. There is some backlash in all axis, between .005 and 0.008. I dropped the motors and checked the pinion gears, it all looks good, the pinions are all new except for the Z but its in good shape. Its a 25 tooth but I think it should be a 20. I have one and should put it it, more torque may help.

I ran a drill program with peck cycles for about an hour with the dial indicator installed in the router and it held the Z position within a 0.002".

The bot is a 2007 PRS Standard 48 x 96 with the 4G setup. I was looking for the ramp rates for this setup for vcarving and cutting 3d plus any other advice that could help.

Tom

Why not show us what you're getting with a photo.

Attachment 30263Attachment 30264

I attached a couple of images. I ran the program two times starting from the top of the block working my way down. I ran it several more times at the last elevation while changing the vr values to see If I could maintain Z height . I also missed steps in x or y, or both.

I also ran the program in air with the dial indicator with different speeds and vr values but always was hight in Z about 0.120".

Ton,

gees, that's madening.

Do the errors occur in the same place each time? And is this happening only on this particular file? Surely there's some simple answer but this is a new one on me.

-I just changed the pinion gear in the z to the 20 tooth, and updated the unit values.
-Adjusted the z roller bearings. Its the older type with 4 on each side, can only adjust the one side.
-I tried different places on the table and it repeats the error, 0.08" -.120" depending on what VR values I change. It cuts 2 fine.
-I have this shopbot for about 2 years and have not used it much. It's the first time I tried Vcarving anything but letters about an inch high.
-I have a bunch of relief files. As a test I programmed these in a YZ and XZ motion. I though it may help because it is mostly moving in only 2 axis. I ran in air with the dial indicator, same error in z. It may be in x and y as well.
-I am running an old labtop, with lost of junk installed, no internet. (I hope that is the issue)
-I checked the diagnostic information after each run and noticed the supply voltage was changing as much as 0.25V. The last time it varied from 0-5.24. I attached a screen shot. Is this a PC or a control box issue.
Attachment 30267

I posted yesterday but it did not update.

- I installed the 20 tooth pinion on the z axis and checked/adjusted the Z v bearings.

-The problem is repeatable at different locations on the table. I ran the UD after each program and noticed a supply voltage being as much as 0.25v difference. Is that a PC or the control box issue?
- I tried some 3d relief programs with raster cutting in xz then yz and there is a similar error in Z.
- I swapped geckodrive from Z to Y , no difference.
- Installed Shopbot on my design PC, no difference.
- Ajusted the geckodrive, no difference. (set pots back to original setting)
- When I had the cover off the controller the lights on the geckodrive dim while jogging 6"/sec, it that normal? One of the drives looks newer and the light is brighter.

NEXT STEP
- Swap out the Z motor with the Y.
- Run a ground from the Control box to the house ground.

Any thoughts?

Tom

It's been a couple of weeks but I found a work around.

I uninstalled SB3.8.42 and installed SB3.6.46 for the older type control card, despite the fact I have a v212 card and V4G. It appears to work and maintain position. I have to search for the serial port each time I run the software. Once the port is found it's all good. I am not sure why it works or what the issue is with the original configuration cutting 3d. The problem is probably between the keyboard and my chair! Any thoughts?
Tom

What have you heard from tech support at shopbot. I would get them involved if I could as this is above my experience.

-I have not contacted shopbot. When I upgraded from the explore card (about 2 years ago) SB told to run the latest version. No issues until I tried the smaller v carving and 3d reliefs.
-I will touch base with them.