im experiencing a very similar issue. Z motor changes direction or fails to respond. This issue just started happening, and it doesn't occur until midway through the job. I swapped cables, terminals motors, USB... My current thinking is that there is an issue with the Black Box. The PCB and components looks fine, so i'm feeling stuck.
See docs:blackbox:faq-identify-motor-coils [OpenBuilds Documentation] - a wiring break or loose terminal where only 3 of the 4 motor wires make solid contact - would cause the issues you describe
That really is almost always a wiring issue - it could even be a problem caused by the vibration of the machine moving around or a wire being pulled out of line. If it was the stepper driver on the muscle board of the blackbox I would expect it to be a problem from the start of the job. It could be a connection problem on the circuit board, so it's worth a look inside (power off obviously) but those symptoms are caused by one wire to the stepper only making an intermittent connection. It's also worth checking the cable with a meter while wiggling the wires around. Alex.
Thank you for the response. I agree, this issue has all the hall-marks of a loose cable/terminal. Ive, swapped out the cables and the motors and the USB. I should say, everything has been running fine for weeks. The failure happens several hours into the job, and does not resolve until I restart the black box. I'll check the black box again and maybe try hard-wiring the motor cables. Are there any recommendations for superior grbl controllers?
See docs:blackbox:currentadjustment [OpenBuilds Documentation] (Does the red LED come on?) Also check grubscrews on pulleys/shaft coupler. Motor may be spinning but pulley/coupler slipping on the shaft/leadscrew - later in the job when cuts get deeper and excert more force on a coupling with loose setscrews perhaps
yes, thank you. all the mechanics were removed and rebuilt. The issue seems power/signal related. ill try running the same job from a different computer (not sure what to look for (other than USB port issues)
Definitely not a comms issue, as per the offered advice. Usb/comms errors result in clear errors in the log. From your description its motor wiring. Unless you'd like to redescribe the error. Randomly changing direction / stopping is almost always 3 of the 4 wires still making contact.. Broken wire inside insulation somewhere etc
hmmm... The problem persists. I am experiencing a loss of X-Axis position many hours into a 50+ hour job. The position loss in not a "drift" in X position over time, rather, there is a clear momentary error which loses the X-Location. This has also happens on the Y-axis on a recent job. My instinct continues to point towards a data/signal problem. The next step is to baby-sit this machine for 50+ hours to see if I can detect a momentary mechanical error. The Gcode is correct when I preview it in OB software and other Gcode viewers. 1- mechanical system of CNC has been rebuilt. (runs good and sounds good) 2- motors have been re-wired with brand new wire (off the spool) 3- disabled PC sleep settings to prevent computer from going into power-save mode next steps: -add ferrite cores to signal and Data cables - install a USB Logger to try and catch any data drops. - test alternate GRBL Control Software - add additional grounding questions: - Could the Open Builds controller be affected by internal clock error of the PC? - Is there a Baud Rate setting that can be adjusted ? - Does Open Builds controller have issues running jobs longer than 24 hours? - Is anyone using an alternate control software like Cura or Octoprint fr GRBL job control?
i do receive the following error in the Gcode editor: 01 File "A1_500K_x.gcode" is too large (57922kB) to load into the GCODE Editor. 02 If you need to edit it inside CONTROL, please use a standalone text editing application and reload it the machine still runs even though the file won't load into the gcode editor
How about heat buildup in the Blackbox? Everything properly cooled? How about adding a desk fan pointing at the BB+PC from 4 feet away. Simple test, cheap to do, easy go/nogo analysis, if you get a successful 50hours job then it was the heat. What software are you using to generate your Gcode? If it is Fusion360 or similar, then definitely turn on 'smoothing' to reduce the number of lines in the Gcode. Maybe you can also split the job into smaller parts so nothing runs longer than 12 hours (or whatever suites you so you can start a new segment at convenient times)
The drivers in BlackBox properly cuts out (Fault LED lit, stays in protection mode until power cycled) so would be more noticeable The xPro had DRV8825s and they could cut out for a split second and then re-enable themselves - causing the random step loss symptom Perfectly fine, we just skip loading it into the Editor mode if its too large to save some memory - people rarely edit gcode inside CONTROL so for large files it saves a lot of resources just to not allow editing Including USB Selective Suspend (can be active in non sleep modes too, you have to edit the Power Profile to confirm). See section 4.2 of docs.openbuilds.com/blackbox By how much does it suddenly jump? Some pictures of the symptom may help too. How have you set your Max Rate and Acceleration settings? Comms errors and the like leaves clear errors and logs. Loss of position is very unlikely to be software/usb/IT related. More likely mechanical, wiring, aggressive cut parameters, etc
Thank you all for the helpful insights! The BlackBox does seem to be running hotter than I would expect. I will add an external fan. An overheating driver make sense to me as a possible cause. notes: - I am using "Vector2Gcode.exe" to convert SVG to Gcode. I have been using this software successfully for over a year with a variety of controllers and machines. - the Gcode files produce by "Vector2Gcode.exe" preview correctly in the OpenBuilds Controller as well as other Gcode Preview software. This tells me that the problem is downstream of the Gcode generation. next steps: - Disable the "USB Selective Suspend" settings - Add an external fan - I have broken the file into smaller jobs, be in the future I will needs a controller capable of running larger (3million+) line of code without interruption. feeling like we are getting close to a solution!
Grbl only deals with 10-15 lines at a time - see Grbl v1.1 Interface · gnea/grbl Wiki The host application keeps the buffer full. CONTROL is often used for files much larger than yours, its not the issue. Buffer issues, USB issues, etc would all have a log entry and stop running... Shifting is almost always mechanical (or at least mechanical induced by something like acceleration values set too high, or max rates set too high causing motors to stall on long/loaded moves, or intermittent wiring break causing a motor to stall, a shaft coupler to slip, etc) Extra fan won't help, see: If it was Temperatures the Fault LED would be on and X axis stopped in place until power cycled (See docs:blackbox:currentadjustment [OpenBuilds Documentation] ) - it won't just continue on
Addition of an external fan and disable the "USB Selective Suspend" settings solves problem. thanks again everyone for jumping in to help trouble shoot this problem. I disable the "USB Selective Send" and added an 8-inch house fan to my setup. The fan is blowing cool air from 6 inches away directly into the perforations on the top of the Black Box. With this addition the machine has been running constantly for over 50 hours. The internal fan on the Black Box in no longer running, (this could be the result of an internal temperature switch for the built-in fan). Based on my experience with the computer and machine being used I suspect the issue was overheating, and not the "USB Selective Suspend".
BlackBox fan is an always-on fan, order a replacement 60x60x10mm 24v fan (amazon, etc) so you don't need the 8 inch fan
I am having an issue with my black box not holding the z axis ..It is as if it is not enabled unless it is being moved .It will drift down just sitting there.Is there a setting to keep the stepper motors enabled when the machine is powered up and not moving so the motors are locked
yes there is such a setting, and the default for OpenBuilds profiles loaded to a Blackbox is 'always on' , I wonder what changed it? (might indicate some other problem) anyhow, you can set it to 255 to have the drivers always on. access the 'grbl settings' tab in CONTROL set $1 to 255 click the save button at top left, it will turn blue when you need to save something but wait, what if it is already 255? then we need to delve deeper into your Z axis, how it is made and how it is set up, the BB current setting for Z, and so on.
