MakerGear Forum

I now had this happen several times. The first was while printing PETG, the last several were while printing Polypropylene. Something apparently jams the filament below the drive gear, and the filament buckles at the gear. I could not find any obvious jam or rough spot in the tube below the gear, so I am presuming the nozzle was at least temporarily restricted, causing a backup, leading to seizure of the filament, causing the gear to eat away some of the filament but still propelling more filament over the top of the ate-away place, resulting in the buckling. Anyone else see this before?
Polypropylene is rather pliable, but the PETG is not, so the pliability is not the entire cause. Several, (but I do not think all), of the times it happened, I was using a 0.25mm nozzle. I had set S3D for that, so it "should not have" been the problem, either.
As a side note, my original extruder has the big teeth, while my dual extruder addition has small teeth. It was the big toothed gear that had the failure. Are they more susceptible to jamming? Any reason for the difference?

0.25 mm nozzles are a real challenge to print with. ANY small particulate can block the nozzle and cause at the very least a partial if not full blockage. If you have eliminated the filament randomly changing diameters as the reason this is where I would start looking. Things you can do

1) Cold pull the nozzle several times to make sure there isn't any blockage
2) Run a filament wiper. Basically a cloth or a piece of foam that wraps the filament before it goes into the feed tube and wipes off any crap that might be on the filament. Some people swear that oiling the filament as it goes through the wiper helps, but opinions differ on if thats needed with full metal hotends etc.
3) When switching filament types, make sure you run some cleaner filament through before the switch. If you are going from say PLA to PETG with a much higher print temp, you can char the PLA left in the hotend when you ramp up the temp and thats all the blockage you are ever going to need.

My rule of thumb is unless you REALLY need that .25 detail then avoid them like the plague.