Printer skipping (Mk2s)
Hi everyone,
I got my Mk2s about 2 months ago and it has been printing very well with eSun PETG (red). About a week ago I changed to Hatchbox PETG (gold) and the failure rate went up significantly. I thought it might just be differences in the filament itself so I did some more tuning and then it printed an 8-hour piece pretty much perfectly. The next piece, however, it stopped extruding in the middle of the print. When I tried again it would intermittently stop extruding and then begin again, seemingly at random, which obviously ruins the print. Since about 3 days ago I have not been able to print anything successfully due to this problem. This is what I have tried:
1. I thought it was a clogged nozzle, so I cleaned the nozzle (using the needle from the kit) and checked the flow when using Load Filament. Assuming filament does go through, the flow is steady and straight, so I don't think the nozzle is clogged.
2. I unloaded and reloaded the filament. When unloading, the motor turns but is unable to push the filament out and I had to repeat it a few times and apply tension upward to get the filament out. I cut the filament a few centimeters above the end and reloaded the filament and this time it went through perfectly. I don't think the extruder motor is the problem.
3. I checked the hobbed pulley to see if it were dirty and preventing the teeth from gripping the filament. The pulley had some debris, but not a lot and it is clean now.
4. I loosened the spring screws on the side of the extruder housing to see if they were too tight and preventing extrusion. This actually made it worse. I then tightened the screws and this improved it, but only temporarily. I also increased the flow in the printer to 151% and that seemed to help, but again only temporarily.
Can anyone advise? This is very frustrating and I am worried something important is broken.
Re: Printer skipping (Mk2s)
sounds for me as if one of your wires is broken and at a certain position (or height) interrupts the extruder stepper to work properly.
or one of your connectors has gone loose at the rambo.
but there might be a lot of other possibilities too:
at which ambient temperature are you printing ?
do you print inside an encolosure.
is your extruder fan (the one at the left side) working properly ?
what are your slicer settings (retraction > 0.8mm ?) ?
do you get the same problems when printing objects from the genuine sd-card ?
is your filament spool running free, or is there any blockage at a certain position ?
do you still use the genuine spool holder ?
....
dem inscheniör is' nix zu schwör...
Re: Printer skipping (Mk2s)
Thanks for the response. Here are my answers:
1. Ambient temperature is circa 25 degrees Celsius.
2. No enclosure.
3. Both fans are running, as far as I can tell (the larger fan only turns on after the wipe, but afterwards it is running).
4. I have a 2 mm retraction at 50 mm/s with a z-life of 0.5 mm. I wanted more retraction because PETG strings a lot, but I also didn't want too much for fear of pulling hot filament into the non-heated part of the nozzle.
5. I have not had any issues printing the Prusa logo or the frog from PLA. My prints using red eSun PETG for ~1 month were also not a problem. This problem began about 3 days ago with Hatchbox gold PETG.
6. The spool can rotate freely.
7. I am still using the 2-sided spool holder from the kit.
If it were a wire connection issue, how would I check that?
Re: Printer skipping (Mk2s)
Ok so after some more investigation I think I have found a potential answer. I opened the extruder housing again by removing the 2 spring screws and rotating the piece down to reveal the hobbed pulley. This time the hole where the tightening screw was became visible and I found no screw there:
I assume this means the extruder motor is turning, but the pulley is not and therefore cannot push/pull the filament. What can I do about this? Can I get a replacement screw from Prusa?
EDIT: apparently the image tag isn't working so the link is: http://imgur.com/aNaQDyn
Re: Printer skipping (Mk2s)
Yes. That would cause the problem.
This is a standard set screw (sometimes called a grub screw). You should be able to find it at a local hardware store.
But the Prusa on-line support should be able to tell you the size.
Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage or loss. If you solve your problem, please post the solution…