Resume on Pause causes extruder to jam
I have tried to use the Pause on Layer feature, or just Pause button during a print, so that I could switch filament colors.
In both cases, the printer seems to do a few odd things. Sometimes it will reverse the extruder stepper to unload the filament while it's moving back to the print, other times, it will extrude faster than the nozzle can handle, causing large blobs out the extruder and I can hear the tension bearing and hobbed gear popping against the filament. In some cases, it grinds away at the filament enough that it jams. When I extract the filament, I can see that it's chewed halfway through on about an inch worth of filament. Makerbot Desktop didn't do this to me, but it's inflexible for a lot of other things.
I have a Makerbot Replicator 2 and a Windows 10 64 bit machine. I have Matter control 1.7.5
Why is this happening? what can I do to correct it?
Pause on layer 2, I manually moved Z up 20mm. When I resumed, it went straight down, then extruded several mm rapidly and paused, retracted the filament completely then attempted to extrude it back, causing a jam. I couldn't get it to refeed so I paused again, had to melt a bit of filament and stick it into the feed to grab a blob that had hardened above the cold end and after the extruder gear. then I was able to refeed. When it resumed, it did the same thing, but twice in a row. I wasn't able to refeed it while it was moving.. had to cut the filament clean and jam it in while it moved. ruining the first of 3 pieces.
They're at default AFAIK. Pause says G0 X0 Y0 ;set warming position
Resume says "@restore_xyz_position
On pause, it actually goes to the opposite corner from "home".
I've tried swapping filament several ways. the first was to Z up about 30mm then manually swap the filament without sending any commands to extrude/retract. Just push the lever down, pull filament out and push new in. BUt sometimes that causes a jam. So I tried to Extrude+. But then it does Retract nonstop until I power cycle the printer.
I enabled Print Recovery and tried again. When it started the odd extrude behavior on pause, I power cycled the printer and told the software to recover the print. But it does weird random movements (went to home, went to opposite corner, sat forever.. moved to various places above the print area but didn't extrude anything... sat there a while, moved again..and doesn't actually print anything.
If I blank out the pause and resume boxes, it stops directly on top of the print. If I Z+ and manually replace filament, when it resumes, it drops down onto the print and extrudes a large blob before resuming the print. If I place a disposable feature (Extra, small part) off to the side and move it around until it's the last part when it pauses, I'm able to remove the blob and part.. but then when it returns to that area, it extrudes material that sticks to the extruder tip and gets deposited later on when it returns to the normal part...