MK4, Nextruder, TPU and clickety click
I had thought my MK3 then MK3S+ were solid, but my MK4 simply printed, everything, easily, and without issue.
Well, until I loaded TPU. The spool was new along with 6 hrs in the dehydrator before printing. It started to load then the filament ingestion halted before any filament appeared at the nozzle then the Nextruder started making a clicking noise. I was stuck at that point. Load or unload resulted only in clickety click.
Eventually I swung open the idler swivel and found the filament had apparently gotten into the are a between the gear and the backing plate then the rotation of the gear fed more filament into that area between the gear and the backing plate. The first picture shows the situation; I had already cut and pulled the incoming filament for a better view before the first picture was taken.
Removing the filament was not easy. Eventually I removed the cover from the planetary gears then moved them out slightly to provide a bit more room in the aforementioned between area. Even with the bit of extra extra room it was effort to pull the filament), but eventually it was all extracted. In the second picture, the filament above the hex tool (the side opposite with the the OG/BL dyke handle) was what had been pulled back into the behind area.
After extraction, clean, and reassembly my MK4 is again working smoothly. However, I am very leery of trying another pass with TPU in it.
Any suggestion for a safer more reliable way to print with TPU?
RE: MK4, Nextruder, TPU and clickety click
Have a look at this: https://www.printables.com/model/596608-nextruder-modified-idler-lever
Watch the video, read the comments and print the replacement parts from PC-CF if you have some of that filament on hand. Otherwise use something a bit more heat-resistant like ABS or ASA.