Hi all, The two nema 23 motors controlling my gantry (x) and vertical (z) threaded drives have started slipping. I have two (same) motors running belt drives on my (y) axis, one each l and r rail which seem to be fine. This is a relatively new machine, I am still in trial mode purposefully not running heavy load cuts while I dial things in. Eg. 1/4" depth of cut, 33% stepover, 1/2" carbide upspiral bit, 15 ipm cut speed, 2.2Kw water cooled spindle. There are probably no more than 15 hrs total cutting time on these motors. I'm guessing I'm just overloading the motors and its time for an upgrade to hi torque but I thought I would throw this out first. Thoughts? thanks, dkw
1) check grub screws on shaft couplers (could be slipping on the motor or leadscrew side) 2) check current adjustment on motors 3) check acceleration and max rate configs 2.2kw spindle is quite overkill and probably too heavy though
Grubs crews and shaft couplers are tight, the slippage is internal Where do I find current settings? acceleration is set at 500mm/sec2, max rate is 5000mm/min x,y and z I bought the 2.2 K spindle as a package deal on amazon great sale price and water cooled is very quiet. It is a blessing. "overkill" probably, I was looking for 1.5 K but was not finding one with er20 collet. I wondered about the weight and did not use the MASSIVE mounting block as a precaution... thanks for the quick response!
Are you using a BlackBox? the current is set with the drivers not the software, on the Blackbox there are current adjust pots. When you say "slipping" you mean loosing steps? noisy and jittery? Gary
Reduce your max speeds to 2500 mm/min. If that fixes it gradually increase it until you get problems again. Alex.
Yes, I should have mentioned black Box. I found the doc from another thread, looking at that now. Slipping is the best way I can describe what is happening. The motor feels like it is still turning internally but the shaft is not spinning. It is not a skip or stutter like jumping the belt teeth, a discernable "groan".
OK, max speeds reduced to 2500mm/min. I've just run the file I noticed the slipping, 3d surfacing with the largest bit I use a 2 flute carbide 2" dia ball end cutting 1/8"deep, 1/4" step over, 25 ipm. roughly 30 min cut time, no problems. Motors noticeably cooler. Thank You All...! dkw FYI, cutting a spruce soundboard for an archtop guitar.
Yours, I'm crossing my fingers the max speeds was the issue, I reduced them and the "slipping" disappeared.
Posting here to avoid need for new thread.. (hi Peter). Struggling with a Z axis in a similar way to the OP here on a retrofitted plasma cutting 3 axis machine. X32 Black Box. Setting up the machine and all fine until I calibrated all the axis having finally connected to a PC. X and Y are fine and went without a hitch to now give accurate measurements and run really smoothly. Z axis now stalls out causing a buzz from the motor as if it IS turning but it isn't (all 3 steppers are older 8 wire NEMA 23s, wired into 4 wire, coils pairs checked OK). All axis jogged/continuous move OK before the calibration. Z now stalls. Adjusted Z motor current but found no solution. The thing that confuses me when it comes to logic is: the calibration move of 50mm in the Wizard moves smoothly and correctly on the Z axis to do the calibration, and it is accurate in it's travel and measurement. Jogging and constant moves on Z are still stalling afterwards. Have not attempted to run a dry job yet as obviously something is wrong. So...will probably rewire from Z motor to black box first to eliminate chance of intermittant short from out of nowhere, then research variables in the OpenbuildsControl setup that I need to tweak specifically for the Z axis. I am not near the machine but will post OBC settings and anything else useful like the stepper specs asap if it would help solve this problem. Thanks in advance for any pointers here.
Possibly Max Rate set a little high - seek and jog moves moves at Max Rate. Calibration wizard moves at a low set feedrate Grbl v1.1 Configuration Could also be acceleration Grbl v1.1 Configuration or could just be that the Z axis is a bit heavier, and the 8-wire motor's electrical specs in this configuration is just a tad too much, maybe too high inductance (limits top speed) or too high resistance (limits acceleration) both feels like a stall
Thanks for the quick response, what you say above is perhaps the place to start by checking and setting up the two things you mention. I would say that the weight of the Z axis is not the problem because all worked fine before so I don't believe it's a mechanical limitation but an electrical setting. My actual conclusion is that something in the config changed after connecting a PC running OBC to the X32 Box via a USB cable, that's when the jogging Z problem manifested. Before that, it was a laptop also running OBC that jogged fine using the interface. I will compare the OBC settings as I'm sure there is a clue to what is perhaps my own "stoopid" at work. Thanks Peter, will keep you informed.
all the controller settings are stored inside the controller, so plugging in a different computer will not change controller behavior.
OK, been tweaking and sorted many things by juggling settings for the Z axis stepper. It now moves smoothly although it could be tweaked further I'm sure to adjust the speeds. The important part was, I was able to calibrate it finally for accurate stepping measurements AND have the axis not stall any more. Yay! Actually cut a simple circle in celibration (bad incomplete cut but worked) and now have to deal with EMF/EMI for efficiency but the proof in the pudding happened today. Thanks!
