I have an OX style cnc that ran fine until a few days ago. Suddenly three of four stepper motors are unresponsive. I had just changed my steps/mm setting to adjust for positioning inaccuracies but otherwise the machine was unchanged. So far I have tested all the wiring for bad connections - everything has continuity and seems fine. As far as I know, my settings are correct but I'm not an expert at this and might be missing something obvious. I've connected to the cnc from two different computers using both openbuilds control and bcnc. One stepper motor engages when the machine powers up but that's it. Nothing moves and homing cycles fail. Any suggestions? I'm stumped. Nema 23 motors. MKS DLC V2 controller (came with the smw3d kit I bought. There's zero documentation for this thing that I can find.) $0 Step pulse time [us] 10 $1 Step idle delay [ms] 255 $2 Step port invert [mask] 0 $3 Direction port invert [mask] 4 $4 Step enable invert X $5 Limit pins invert $6 Probe pin invert $10 Status report [mask] 1 $11 Junction deviation [mm] .01 $12 Arc tolerance [mm] .002 $13 Report inches $20 Soft limits $21 Hard limits X $22 Homing cycle X $23 Homing direction invert [mask] 3 $24 Homing feed [mm/min] 50 $25 Homing seek [mm/min] 300 $26 Homing debounce [ms] 250 $27 Homing pull-off [mm] 5 $30 Max spindle speed [RPM] 12,000 $31 Min spindle speed [RPM] 0 $32 Laser mode enable $100 X steps/mm 53.333 $101 Y steps/mm 53.333 $102 Z steps/mm 400 $110 X max rate [mm/min] 2500 $111 Y max rate [mm/min] 2500 $112 Z max rate [mm/min] 2500 $120 X acceleration [mm/sec^2] 100 $121 Y acceleration [mm/sec^2] 100 $122 Z acceleration [mm/sec^2] 10 $130 X max travel [mm] 574 $131 Y max travel [mm] 762 $132 Z max travel [mm] 76.2 $140 X homing pull-off [mm] 200 $141 Y homing pull-off [mm] 200 $142 Z homing pull-off [mm] 200
Try $4=1 Or upgrade to a BlackBox with lots of Documentation and Support: see start [OpenBuilds Documentation]
Thanks! Turns out that was a typo, a few actually. Now corrected. It was set to 1. But I played with the setting, on and off. $4=1. Z responds to a homing request but it just vibrates violently in place as if it's jammed. Powered down the motor spins freely as it should. I rebooted the machine and Z still just vibrates.
I appreciate the link. I've gone through the machine checking continuity and looking for anything shorting to ground, etc. Everything looks fine. There's good continuity from the control board through to the motor and the motor coils are wired correctly. I'm suspicious of the control board itself, that it's not sending commands correctly. But I'm not sure how to test that.
In an ideal world you'd oscilloscope it, but the quick'n'dirty statistical way is to swap motor wires over (whilst unpowered). If it also doesn't power a second motor correctly, it's less likely that two motors and/or two cables are bad, more likely that the single common point- the board itself, or the driver- is bad.
Spinning steppers by hand while they are connected to a driver is dangerous. The spinning motor acts like a generator, backfeeding the drivers output stages. This can damage the drivers
Peter - Speaking of things I know in theory but hadn't connected in practice. That's good to have in mind. Thank you. I'm not really sure what the problem was but at the moment I have full control of all axis again. I tweaked with some settings but related to inverting direction of motion and motor steps per mm. Why things were unresponsive in the first place is still a mystery. Fingers crossed for now. Thanks for the help.
