help please, anyone able to help identify this print issue
I have quite a few MK3s printers and two of them are having this issue. I print pretty much 31 (you know, 24/7 😀 if you know the reference hehe). Anyways, in the prints themselves this is coming out as looking like under extrusion.. I have completely rebuilt the extruder/hotend multiple times, new printed parts multiple times (ABS and PLA), nozzles, heat break, heat block, ptfe tube etc etc with the same results. So I am guessing extruder motor issue or extruder stepper driver issue at this point? I have even tried raising the voltage to the extruder motor via M907 EXXX command in beginning of my gcode (tried from 600 up to 750, 535 is default I think it is), no difference. Any thoughts on what is going on?Â
Thanks!
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RE: help please, anyone able to help identify this print issue
Please post some pictures from the first layer and/or some actual prints. The prime line can't be used as reference for any troubleshooting.
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RE: help please, anyone able to help identify this print issue
@nikolai
One on top is normal, bottom is from messed up printer. I had shown the purge line because it gives a good perspective on how its acting.. running normal speed then slowing down, normal, slow etc.
Thanks for any input.
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RE: help please, anyone able to help identify this print issue
Are you saying that when extruding a straight line, your linear speed will change for no apparent reason? I am asking because I have notice this as well on one of my gcodes.  It's a straight line about 5" long, but the printer will print fast-slow-fast for some of the passes.  On other passes, the speed is constant which is what I would expect. I wonder if this is some slicer or firmware bug.  I'll try to get a video of this next time I print that model.
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RE: help please, anyone able to help identify this print issue
@twoballscrewball
I am not sure if its the speed changing or what.. it seems like it is though by looking at the purge line. In the prints themselves it looks like that too, with normal extrusion then under extrusion then normal etc. Very strange and I don't know how to fix it. I just ordered a new rambo board and extruder motor from prusa yesterday, going to swap them once they arrive and see if that fixes it. Â