Suddenly underextrusion?
Hello I have a problem I don't know where to exactly start to get it sorted. In the last weeks I printed many parts with the regular 0.4 brass nozzle and the prints were fine. Than I switched to a 0.8 nozzle-X and printed many big parts which were fine as well. After all big parts were printed I witched back to 0.4 but Nozzle-X as well. At the same time I updated octoprints camera-plugin. Now since than I got more server offline alerts on octoprint – might be coincidential but as well massive underextrusions it seems. The nozzle itself is tight enough, so no filament leaking out on top of the hotend. Changing Filament, same results. I tried to calibrate the e-steps with the guide from teachingtech (Youtube) and got prett mixed results. Default value was 280 e-steps after first round it said I needed around 320 but than it extruded still not enough and even less than before! Doing the same value again it extruded too much, so less again. So at some point I gave up and estimated until the calibration cube looked okay which was than at 310 or 315. Hollow 1-wall calibration cube to measure the wall-thickness went well as well without under-extrusion, so I thought okay problem solved, printing time again 🙂
Than I started my print and it has massive under-extrusion 🙁
Any suggestions on where to start or a checklist for things to check systematically so I can delete one item after the other until I find the causing factor?
RE:
Your first picture looks like a partial nozzle blockage. Some replacement nozzle require a higher temperature then stock ones.
RE: Suddenly underextrusion?
If you are still using the regular / original extruder on the MINI my tip is, that you have the "bowden tube problem" which is common to MINI, when changing nozzles. I am sure you can find tons of posts here in Prusa forum. My solution is very simple. When everything in the extruder is clean and the new / other nozzle is in place and again cooled down I open the 3 small worm screws which holds the tube of the extruder in place. Then I press the heatblock into the direction of the extruder and thighten the 3 small worm screws again (be carful - not too hard!). Doing this ensures, that the small PTFE-tube is mounted correct (without having free space causing these under extrusion problems).
Best regards, Clemens
Mini, i3 MK2.5S, i3 MK4, CClone (Eigenbau)
RE: Suddenly underextrusion?
Yes, I know esoecially if you change from brass to hardened steel but I already raised temps up to +15 degrees…
RE: Suddenly underextrusion?
Okay will try that tomorrow than, thanks for the hint!
RE: Suddenly underextrusion?
So a little update – but since my family all had Covid there was not much time to tinker with my printer. But I think I can focus the problem to something mechanical. Because I had to print one replacement part of my big part series with the 0.8 Nozzle and it went kind of better, so less underextrusion but still noticeable. And the printer had problems extracting the filament out in order to change filament – had to do three times and pull. So I guess I'll have to take the printer out of the cabinet again and have a look at the idler of the extruder and the extruder gears. Just the nnob question (since I bought my prusa used) tension of the extruder idler is set with the scres on the left side right?