Xcarve with 2021 upgrade, and the CNC4Newbies Z axis with 269oz stepper. Openbuilds Blackbox X32 and Openbuilds Control gsender. This is at least the third or fourth time this has happened - I start a cut and somewhere the machine loses Z height, and when it does, it goes deeper and then ends up skipping steps on x/y because it's too deep/too hard to keep up. I know the xcarve is as 'rigid as a wet noodle' as someone on here told me once, but the z axis from CNC4Newbies is rock solid - linear rails, screw drive (ball screw?), machined aluminum, big stepper motor. This time I was watching the cut closely - it was a profile cut for a salt cellar lid in maple - .25" compression bit, .07" depth of cut, 50 ipm. Dewalt 611. As I watched the initial pass, it started fine (1" ramp and lead in) and as it went around the top of the circle, it just kept getting deeper until it went all the way through the material and started chattering like hell (material is only .36" thick). After I stopped the job, I moved the spindle over and sent it to Z0, and sure enough, it moved to close to the spoil board. I cut 1" thick white oak with these same settings all afternoon with no issue FWIW. I'm really suspecting that the ****** micro-pc I'm running openbuilds on is somehow fucking this up - sometimes it has a hard time keeping up if I try to jog too often too fast, etc. It was just weird today because again it started out with the right DOC but then just kept going. Also FWIW, I previewed the toolpath in Vcarve and it looked fine. I have not tried another gcode viewer. Any thoughts or ideas? Thanks!
I've had this happen it was an intermittent connection on the stepper motor cable, broke 4 small bits before I realized what was going on. Gary
How did you come to that conclusion and how did you fix it? I have to admit, I did a pretty ****** job wiring in the new stepper motor for my upgraded Z axis.
Did you tune the speed / acceleration settings to suit the new, bigger, heavier Z axis? Most likely you would need to dial them down to avoid missed steps (which are most likely to happen when moving the head up because .... gravity.) Sort that^ out first - you will go around in circles for ever if the hardware isn't reliable (and we don't want to come with you )
I did tune steps per mm when I first got it. WDYM speed/acceleration? As for wiring, I just ordered the whole upgrade kit from cnc4newbies with their wiring kit, so I'll be re-wiring the z stepper this weekend anyway. Hopefully that helps!
Grbl v1.1 Configuration and Grbl v1.1 Configuration (That Grbl Wiki is a must read to understand the firmware) docs:blackbox-x32:faq-identify-motor-coils [OpenBuilds Documentation] is a good read
You need to tell grbl how quickly it can accelerate each axis ($120...$122), and what the top speed of each axis is ($110...$112). These would have been set by the manufacturer for the original machine, but now you've changed it mechanically, you will likely need to re-adjust to suit the new parts. The outline of the process is in the links that Peter posted above.
