MK3S MMU2 Extruder clicking one solution  

MK3S MMU2 Extruder clicking one solution

Hello, I have been very happy with Prusa until after about 1000 meters of printing, I started to have multiple fails on one small part I was making several copies of. After exploring the forums, I narrowed the issue to an Extruder issue, mostly because I heard the clicking mentioned in the forums. I tried the clean out, it did not fix the issue. I watched the video on the extruder pin inside the secondary Bondtech gear. That seemed like it might be the issue because the cover to this jumped when the click happened. But the pin was centered. I did clean out some scraps of filament, this was not the issue as the clicking kept happening. The Bondtech gear moved freely and was firmly attached. I reassembled the pieces and still the clicking kept happening. I closely watched the window where you could see the Bondtech gear while the extruder was spinning and noticed that the click happened consistently as the extruder motor was spinning. The clicking did not happen when the Bondtech gear / piece it was attached to was not installed. I next thought it could be the set screw on the Bondtech gear on the extruder motor hitting the free moving Bondtech gear. I moved the extruder forward and then back to get it to stop exactly where the click happened, lifted the cover holding the free moving Bondtech gear and the set screw was exactly facing where the free moving Bondtech gear was. I then moved the extruder motor forward and back with the free moving Bondtech gear cover removed and noticed that the set screw on the Bondtech gear attached to the extruder motor was partially screwed out allowing the Bondtech gear to slip partially on the extruder motor shaft. BINGO, that was the problem. I tightened the screw, reassembled everything and returned to the perfect prints I was getting prior without any clicking.

I love this printer. Any technology can have issues. We are still in the early stages of 3d printing. I think Mr Prusa has produced an excellent product. It is leaps and bounds better than the Printrbot Metal I previously was using. I love the fact that I can clean off the build plate, tell the printer to print a file and I don’t have to baby sit it. It just works. It’s easy to sit back and enjoy such a well thought out product until something goes wrong. I am guilty of not doing any routine maintenance until something happens. Thankfully, I bought the kit and not fully assembled version, this allowed me better knowledge of how to diagnose and fix issues that come up.

I do wish there was a better way to handle / prevent the little plastic pieces that seem to appear as one uses the printer. I was amazing how many little pieces were around the Bondtech gears when I disassembled this section.

I can’t emphasize enough how happy I am with this printer. I especially love the fact that I can sit down to my IPad Pro and Shapr3D, design something, send it to my laptop and the prusaslicer and a few minutes later, my prusa MK3S MMU2 will reliably start printing what had just been a thought a few minutes earlier. NEAT!

Joe Matusic, MD

Pediatrician and Maker

Charleston, WV USA