Unable to feed filament through Mini 2

I have been able to print several pieces on this mini 2 without issue up until recent.

Midway through a print, it just stopped feeding fillament, and I noticed when pulling out the remaining, there was the typical “mouse bite” from the feeding gear.

I have tried several hot and cold pulls to clear up whatever has jammed, but cannot seems to clear it. I can press extremely hard and get some filament to come out, but its more or less in a pigtail fashion and maybe can extrude only about a 1/2 inch to an inch.

The funny thing is, this happened to the original tool head in which I replaced, then was able to print just fine for a few prints. I noticed that when I printed fine resolution, this happened again to the 2nd tool head. Sucks that now I have burned through 2 tool head units and hope to be able to clear up whatever the issue is on this one as I sheared off the hot end trying to unscrew it on the original head.

Anyways, any ideas on how to free up this jam? Any idea what might be causing this to happen all of a sudden with 2 different units? I have used this PLA and ABS from matterhackers for quite some time now and used it several times successfully.

Thanks.

I’ve had good experience with eSun’s cleaning filament. I get good cold pulls and it usually picks up bits and pieces of the previous filament well.

Make sure you clean the hobb gear (the feeder gear). It would have chewed up filament so the teeth would have dry filament stuck in them. A few puffs of compressed air will blow out the dry filament in the teeth.

As for why it’s jamming… that can be several things. While your nozzle could be clogged, it may also be that the temperature is too low. I’ve also seen this happen on parts that want an excessive number of retractions over a short distance … so the gear is rolling back and forth over the same short distance of filament … chewing it up until it breaks down and jams.

You can change the maximum retractions setting in Cura to reduce this (e.g. drop the value to a number like “5” … the default is 99 which basically means there’s no real limit). The retraction amount on a direct drive printer is typically a low number. Most of the time I use 1mm retraction distance but it probably shouldn’t be above 2mm (there are a few filaments that are exceptions to this).

There’s also a value called the “Retraction Minimum Distance Window”. That’s the length of filament over which maximum retractions is enforced. E.g. if you have 1mm as the retraction amount, 5 as the max retractions, and 2mm as the “Retraction Minimum Distance Window” then what this means is that any job that would call for more than 5 retractions before the printer feeds through at least 2mm of filament (as measured on the cold side) the excess retractions will be ignored. But once it advances 2mm of filament it will start retracting again. Basically you’re telling it not to roll over the same 2mm segment of filament more than 5 times (really 10 times because a retraction is a move up… but then it has to a reprising move which pushes it back down again. So each 1 retraction will make the gear roll over the filament twice.)

If the nozzle is clogged then a cold-pull may help clear it.