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UMO Skipping steps on long prints, tried everything


vnks
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Posted · UMO Skipping steps on long prints, tried everything

Hi all,

I have an Ultimaker Original that started skipping steps on long prints (10+ hours) a few months back. Since then, I've tried everything I could think without making much of a difference. Pretty much the only thing I haven't tried is swapping the steppers. When it skips, it's a bunch of steps at once, like the driver overheats and shuts down. My test case is a 20+ hour print, slow, at 40 microns, so that I don't waste too much filament. I always oil the axes first, movement is smooth all over, no obvious binding. It always skips on the X-axis.

- Replacing the stepper drivers, swapping X & Y - no change, same problem on the X axis.

- Tuning stepper drivers, lowering or increasing the current, no noticeable difference until it's raised too much and it skips more.

- Loosening the belts, long ones and short ones.

- Marking the bushings and rods, to make sure nothing slips - they're not slipping.

At this point I'm out of ideas, I'd swap the steppers if it wasn't such a pain, but I'm not even sure it's possible for the stepper itself to cause this. I did build my own firmware a while back (custom heated bed), but this was long before the problem started and I haven't touched it since.

Any ideas? At this point I'd probably hook up a thermistor to stepper driver heatsinks and start logging the temperature, just to confirm that the drivers are really overheating.

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    Posted · UMO Skipping steps on long prints, tried everything

    How's the cooling? Is the fan running properly, is air getting to the drivers? Maybe try running it without the cover on the electronics and directing a large PC fan or similar on it to see if that makes a difference? (you can let it print while the printer is on its side)

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    Posted · UMO Skipping steps on long prints, tried everything

    If you increase the current and the skipping gets worse then you most probably damaged the driver already (I did so with a driver from UM). Replace it and be careful to set the current not too high (something like 1.1-1.3A is reasonable).

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    Posted · UMO Skipping steps on long prints, tried everything

    How's the cooling? Is the fan running properly, is air getting to the drivers? Maybe try running it without the cover on the electronics and directing a large PC fan or similar on it to see if that makes a difference? (you can let it print while the printer is on its side)

     

    The fan is running fine, it's oiled and produces plenty of airflow. Additionally, whenever I catch it in the act of lots of skipping, if I shut down the print and take off the cover, the driver heatsinks are barely warm.

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    Posted · UMO Skipping steps on long prints, tried everything

    If you increase the current and the skipping gets worse then you most probably damaged the driver already (I did so with a driver from UM). Replace it and be careful to set the current not too high (something like 1.1-1.3A is reasonable).

     

    I've swapped the drivers around, and have a bunch of new StepSticks I've tried as well, no difference - it keeps happening on the same axis.

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    Posted · UMO Skipping steps on long prints, tried everything

    So, what current do you have on that axis?

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    Posted · UMO Skipping steps on long prints, tried everything

    So, what current do you have on that axis?

     

    1.15, as per the documentation. I tried lower and higher as well, it's skipping at all settings.

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    Posted (edited) · UMO Skipping steps on long prints, tried everything

    Have you tried swapping the x and the y motor yet? I mean not only on the Ultiboard but physically...

    Edited by Guest
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    Posted · UMO Skipping steps on long prints, tried everything

    Have you tried swapping the x and the y motor yet? I mean not only on the Ultiboard but physically...

     

    That would be quite involved, I'd either have to re-wire everything or cut and re-splice the wiring... I'm not sure it's possible for a stepper motor itself to cause this - they're basically solid state. I certainly haven't been able to find any confirmation that it could be a potential cause.

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    Posted · UMO Skipping steps on long prints, tried everything

    Could there be some false triggering of end stops going on?

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    Posted · UMO Skipping steps on long prints, tried everything

    Could there be some false triggering of end stops going on?

     

    That would show up on the Ulticontroller, right? Nothing like that is showing.

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    Posted · UMO Skipping steps on long prints, tried everything

    Hi,

    Any other ideas? I have a very expensive paperweight at this point :(

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    Posted · UMO Skipping steps on long prints, tried everything

    You have to identify which component causes the problem. For this you have to switch components between the axes. Remote diagnostics is very difficult; only systematic trial and error will bring you closer to a solution...

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    Posted · UMO Skipping steps on long prints, tried everything

    You have to identify which component causes the problem. For this you have to switch components between the axes. Remote diagnostics is very difficult; only systematic trial and error will bring you closer to a solution...

     

    Yeah, I've been doing it for close to two months now with no progress. I was hoping someone has experienced this with a unique root cause - I've already tried all the common ones.

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    Posted · UMO Skipping steps on long prints, tried everything

    Here's one weird thing I noticed, the head bearings are shifted on the X-axis, same axis that's skipping - http://imgur.com/sdX2dkZ . There's a matching gap on the other side. Could this be a symptom of a hardware issue? Everything feels very smooth, especially after oiling.

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    Posted (edited) · UMO Skipping steps on long prints, tried everything

    Here's one weird thing I noticed, the head bearings are shifted on the X-axis, same axis that's skipping - http://imgur.com/sdX2dkZ . There's a matching gap on the other side. Could this be a symptom of a hardware issue? Everything feels very smooth, especially after oiling.

     

    My ultimaker 2 just started doing this too on the same axis as yours.  I hear a clunk then suddenly the x axis is off by a few mm. i had to leave so I couldn't diagnose it but I found this thread and was surpised that it is from today. It is pretty hot in there right now (93 degrees) which might be part of it.

    Edited by Guest
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    Posted · UMO Skipping steps on long prints, tried everything

    Ok I'm home now and it's hitting the side of the printer. I'm printing something that just barely fits, with a brim. Cura thinks it's ok but on the right side I noticed the brim line was overlapping the previous one so it wasn't moving far enough to the right.. then after a few brim lines it moved outward a bit more and smacked into the side of the printer.. so i guess I'm not having the same issue. I guess Cura has some bugs ;)

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    Posted · UMO Skipping steps on long prints, tried everything

    Ok I'm home now and it's hitting the side of the printer.  I'm printing something that just barely fits, with a brim. Cura thinks it's ok but on the right side I noticed the brim line was overlapping the previous one so it wasn't moving far enough to the right.. then after a few brim lines it moved outward a bit more and smacked into the side of the printer.. so i guess I'm not having the same issue.  I guess Cura has some bugs ;)

     

    Ah, too bad. In my case it probably happened a while ago with a larger model running into the same issues as yours. I think I'll try getting good quality stepper drivers instead of the cheapos I have now, there's some timing support for this being the problem...

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    Posted · UMO Skipping steps on long prints, tried everything

    So, after getting branded black Polulu stepper drivers, and replacing all of them, I have the same exact problem - skipped steps on the X-axis during long prints (6+ hours). Current is set to 1.15 amps, no heatsinks (per documentation, none are needed for this current level with active cooling).

    I noticed that all the skips are in the same direction - it keeps shifting towards the left, if looking at the printer from the front. Is this data point ringing a bell for anyone? I have nothing else left to try other than replacing the main board on a whim :(

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    Posted · UMO Skipping steps on long prints, tried everything

    I have the same problem, and was also convinced that it was an electrical rather than hardware problem. However last night I witnessed it happening, and it was caused by a bind on the mechanical system. I'm not sure how or where yet but I do know it was totally stuck. Once I got it moving again it was silky smooth with no indications of binding anywhere. I think it may be going off-square somehow and binding like that. Or there is something caught in the bearings? I'm ordering new rods and graphite filled bearings today, hope to sort it with that.

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    Posted · UMO Skipping steps on long prints, tried everything

    I've come to the conclusion that in my case there's oil-soaked wood dust in the linear bearings, that needs to be cleaned out. I haven't had a chance to actually do it yet, and won't for a while, but it makes a lot of sense to me. The printer was sitting in a pretty dusty wood shop, and I can see the grime inside the bearings. When I oil the rods, everything is smooth for a while, but a few hours in the dust absorbs the oil, and everything binds up. I'm going to disassemble everything and soak in WD-40 or something along those lines to get it all clean, and keep it away from wood dust in the future. Hopefully that'll be it.

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    Posted · UMO Skipping steps on long prints, tried everything

    My x motor ended up failing not too long ago. It had the same symptom you described where it suddenly skipped a few steps and finished the print with everything on the top shifted to the left. A few prints later the motor seized up completely. They sent me a new one under warrantee. I was able to break the bad motor loose with some oil and turning it by hand. Getting the motor off is easy enough. I would just replace it.

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