Hello CnC Gurus in the Sky, Been using my 1010 for just over a year now. I recently started having problems and am looking for help. I've concluded it is most likely backlash on my X-axis, but I could easily be wrong so don't hesitate to mention other ideas. My apologies in advance for the length of this post. The issue first appeared on a large laser project. Attached is a picture of the result. Simply put it appears the machine gets stuck and then is offset by roughly 1.5 inches. It wouldn't happen every time or on every project which made it frustrating to diagnose. Then I got to a project where it happened every time in almost the exact same spot. I split the job into smaller pieces and remedied the problem once. I finally happened to be sitting right next to the machine when I heard a most horrific sound...sort of like grinding or binding as the machine moved on the both the X and Y axis. I aborted the job and tried to replicate it by just commanding the gantry and spindle around using Openbuilds Control. I couldn't replicate it. I believe it was because I couldn't manually move in both X and Y directions at the same time. When I moved the spindle to a new X, Y, and Z position and told it to return home, I could sometimes get it do it. Here's what I've tried...go easy on any criticism, I was desperate. - Adjusting wheel tensions. - Loosened and tightened just about every screw (3 or 4 times). - Used CRC Dry PTFE Lube on drive screws. - Replaced X-axis drive screw. (Yes I bought a new one, because I hadn't yet stumbled on the threads about backlash) - Replaced X-axis nut blocks. - Pulled X and Z axis gantries apart and put them back together. (I dreaded it, but I did it. Reviewed assembly video along the way and nothing was out of place) - Learned there is something called a grub screw for the Z-axis anti-backlash nut block (not depicted in assembly video)...but I went ahead and added it while every thing was disassembled (I always wondered why that part was left over...grin). I may have missed something I've tried, but those are the major ones. Thank you in advance for any suggestions.
in the GRBL settings page, reduce the acceleration rates to half what they are now and run a job. if it all works fine for this and a few more test jobs, then the issue is binding in the leadscrew or dirt on the rails where the wheels run, even dirt stuck to the wheels. even really small bumps can upset a fast accelerating stepper motor. if you still have a problem, then reduce the max rates and try again. (now we have both max rates AND accelerations reduced). if it works now, then the problem is still dirt/resistance somewhere. steppers are at their least powerful when moving fast. so you will normally see a small problem only when it is doing a rapid traverse. (big problems will show up at any speed, like a seized bearing)
Okie doke. Lots off trial and error. Lots of cursing...lots of cursing. I am cautiously optimistic that I've fixed the problem. David feel free to weigh in. I'm going to try to summarize some of what happened below in an effort to maybe help others, but the one gem that seems to matter the most...DO NOT pull the lead screw collar tight against the bearing and spacer. The saga...I replaced the lead screw on the X-Axis as I indicated above. The problem persisted. I pulled the X-Axis off to check tension on the screws and ensure everything was built correctly. I undid all the Y-axis lead screws, checked tension on all the wheels. Check square on the machine. Put everything back together following the assembly video...but missed one the step towards the end about moving the X-axis gantry all the way forward after connecting the lead screws to ensure it is squared. The result of that was horrific as one side of the of the X-axis ran away from the other tweaking things. Loosened everything again, resquared, tightened, followed video verbatim, and was back in business. I thought. The video I'm attaching shows a new problem with Y-Axis now binding. As problems persisted, I followed David's suggestions about changing speeds and discovered the collar issue half way through them. I discovered it because the leaded screw seemed to wobble vertically during long Y-axis movements. I had noticed a metallic rattle sound on the right side and diagnosed it as coming from the collar. I loosened the collar and pulled it TIGHT against the baring and spacer. As I said above, I eventually came to conclude that was a problem. Hopefully all that made sense. I tried to attach a video I caught of the problem, unfortunately it was too large. I did snap a picture of some of the results. I loosened the lead screw collars in between run 3 and 4. If the problem isn't solved, I will post additional steps. List of things I tried while trouble shooting: - Adjusting wheel tensions. - Loosened and tightened just about every screw (3 or 4 times). - Used CRC Dry PTFE Lube on drive screws. - Replaced X-axis drive (lead) screw. (not necessary) - Replaced X-axis nut blocks. (not necessary) - Pulled X and Z axis gantries apart and put them back together. (probably not necessary) - Added grub screw to Z-axis anti-backlash nut block (probably not necessary) - Tightened and retightened the flexible couplers. - Began adjusting acceleration and max speeds. - Eventually loosened the lead screw collars.
The first pic above isn't backlash that's a whole bunch of missed steps, in other words the motor stalled out. Is this with a Blackbox? big Openbuild motors or something else? have you increased the current? These screw drive systems are strong enough to push you back if you jog and try holding it. Have you posted your GRBL settings? Like Dave said too fast of acceleration or travel can cause this as the torque drops like a rock with speed on steppers. Do the lead screws move freely though the nut blocks? Should be very smooth, easy to turn with your fingers with the motors powered off / disconnected. If not they might need to be broken in. Cheers Gary
Gary, Sorry this response has taken so long. Personal issues have kept me from my shop. After removing the X/Z-axis gantry, I adjust tension on all the wheels, cleaned all the surfaces (didn't find any dirt or grime), I put everything back together, following the procedures in the video. The first couple of tests ran okay. Then on a later test, as the X/Z-axis gantry moved toward the back of the machine the right side ground to a halt, tweaking the entire gantry, and I aborted as quick as possible. I'm using a Blackbox controller and the big open builds motors. I haven't increased current. How do I do that? One thing that I'm still concerned about...the lead screw on the right side is more difficult to loosen by hand then the left. I have switched out the lead screw, nut blocks, and used the propper lube, and still if the nut blocks are tight, the lead screw can be manipulated by hand, but is not as easy as the left. How do you recommend I break them in? Thank you for any and all help. I'm very frustrated and appreciate any/all help. Rob
Sounds like wiring. Grinding noises being the clue. See docs:blackbox:faq-identify-motor-coils [OpenBuilds Documentation] Intermittently one of your 4 motor wires has a break
Like Peter said could be wiring for sure, but to break in the nut block you can chuck the lead screw in a drill and run the block up and down the screw till it's more free. If it's the anti backlash type make sure the little grub screw isn't tight.
Okay. So I checked wiring continuity to the motor I thought was having issues (right side y-axis) using a meter and attempted to "break in" the nut blocks using a drill on both sides. I decided to flip the left and right y-axis motors to see if maybe the motor was the problem. I adjusted wheel tensions and checked square. When I ran my test (setting a home, moving the x, y, and z, then telling the machine to return home) the first test ran fine but number two hung up again this time on the left side. Got me thinking maybe it was a motor problem. Frustrated I realigned everything and this time filmed the test. Of course this time it looks like both left and right sides of y-axis hang. I'm going to try to upload video and pic of log hoping y'all can help me finally fix this. To complicate (or maybe explain) matters more, a little while later when I attempted to turn the system back on, it wouldn't respond. I tried the on/off switch multiple times and then for no apparent reason it popped on. Could that be the ultimate culprit??? Faulty power supply?
Hi Rob, what's the speed set to for that Y move? are you using the default machine settings? Please post your settings. Check and recheck your power connections, looks like something is intermittent, probably not the supply itself but a connection. Cheers Gary
Gary, Thank you for your continued help. Right now, using OpenBuilds LEAD 1010 with Laser Module default settings. Pics of actual settings attached.
The laser profile has higher acceleration/max rate Adjust down accordingly, something on your machine is a little tight. Or do you have any 3rd party components (different motors, etc) perhaps?
Yes, as mentioned, dial down acceleration / max rate. Profiles are recommended settings, but one should tune your own setup. Being a kit sometimes a machine is just built a bit differently. Or its still new and not bedded in (leadnuts tight, wheels adjusted too tight)
