MMU prints missing layers
Hello!
I can't use the MMU3.
The problem I am seeing is that there are layers where one color will not print. Funny enough, the other colors print just fine, at least for those layers.
The problem has presented itself on primarily a couple of colors, while one color has always printed fine. Also, I never once had this problem with MMU2. The biggest problem has been using Prusament PLA.
I have chatted a couple times with Prusa Help technicians but my problem has not been resolved. First they had me do a cleaning pull, but there was no problem in the hotend, it came out clean, but I also repeated that. They had me turn out the extruder gear tension. I turned it out 1/2 turn at a time (then I tested with a print), 2 full turns (starting with screw head flush to the left side body, without filament present). I never saw an improvement.
I have a print that I have been trying to accomplish for the last 2 weeks, and the print fails every time. The problem is in the extruder. Upstairs the MMU3 works wonderfully, no problem with loading to the extruder. I re-adjusted the filament sensor, and made it as un-sensitive as possible (so it would barely sense the filament was loaded), but it isn't sensing that the filament is not making it past the gears.
How come the filament is not being fed to the extruder, but the filament sensor is not seeing the problem?
If anyone has an idea of what to try, I am all ears. I think the handoff to the extruder is not working correctly, and that the MMU3 needs to push the filament a bit longer as the filament starts to be engaged by the extruder gears.
Mike
Best Answer by S'Mike:
Found the fix - the PTFE tube in the hotend was mangled from use, it took a close inspection to see that it was no longer tapered on the top, and the filament was not always making it past the lip. Amazing how much of a difference this makes!
RE: MMU prints missing layers
Found the fix - the PTFE tube in the hotend was mangled from use, it took a close inspection to see that it was no longer tapered on the top, and the filament was not always making it past the lip. Amazing how much of a difference this makes!
RE:
i have similar issue, what does not make sense is if the one color is not working and the others do...if the main pfte tube that engages all colors, why is it affecting one color and not all the colors??
RE: MMU prints missing layers
Try trimming the end of the filament for the one that doesn't work, there is something different about the filament probably.
RE: MMU prints missing layers
I am using Mk3.5 with MMU3 & since loading the recent firmware update (Firmware 6.5.3 /3.0.4) and have observed that intermittent layer shifts are occurring when MMU filament load baulking occurs and either automatic retry or manual intervention happens. Can't prove it numerically but it seems that I am also getting more baulks with filament changes than before.
Haven't had this problem in 3.03 version. I am going to revert to previous versions (for me that is 6.2.4/3.03) to verify that it is not a hardware issue and will further update this post.
RE: MMU prints missing layers
Update to yesterday's post - Reverted my Mk3.5/MMU3 from 6.5.3/3.0.4 back to 6.2.4/3.0.3 and had no issues with a 10hr 4 colour 192 tool change print so I don't think I have a hardware issue.