The weirdest problem I ever had

[jonatanrullman 17]

I just had the weirdest 3D printing experience.

I had twelve parts printing on my UM2. After a mm or so one part came loose but everything else was looking so great that I decided to let it run and see if it would just air print and get all the other parts out fine anyway.

This worked alright up to about 10.5mm at which point the printer went complete haywire. It got to the bad part (probably a coincidence) and all of a sudden in went straight forward until it came to the very front of the printer, all the way laying a string of plastic at about the usual rate. It then returned and continued printing the next part in line.

However, it laid an almost solid layer instead of infill. It then continued laying parts at the rights spots but I noticed more of the solid instead of infill.

Later, can't remember if it was the same layer or one layer later it moved very slowly in a straight line for perhaps 5 seconds while pumping out masses of plastic, like it was priming. At the same time the display was wobbling like crazy.

After this is continued laying layers almost perfectly for all other parts, but like it was several layers ago (about 5mm, this in fact appears to be the cause of the solid layers instead of infill I mentioned earlier) because some parts had tapered off or had bevels and such and it was laying plastic in the wrong places. At first I thought it had lost steps but it was perfect on all sides and parts where the perimeter had not changed.

This continued for another full layer while I was sitting there looking amazed. It then started going slowly again on the same part but this time it retracted the filament halfway back through the bowden tube. Again, the screen was going back and forth several millimeters to each side). It then continued as it should, feeding the filament through the tube in the normal rate, though obviously nothing came out of the nozzle.

At this point I started filming but it didn't happen again for a couple of layers and I got tired of holding the phone up for severalk minutes. So I cancelled the print and I am currently printing all the parts in a couple of batches.

I should mention that I am running Cura 2.5.0 on Mac but Thinkergnome (can't remember which version but it is a couple of months old). I have run these versions for hours and hours without problem. I printed at least 20 hours this weekend on that printer alone and a couple of hours more on my other one.

I really have no idea what happened.