Yet another jammed extruder thread,

Yeah, I've searched, and I found other instances.

I now officially hate my extruder design. Just for the record.

So, I left my printer printing up a new case for my RAMPS box, and came back to find that at about the 4.5mm mark, it just stopped extruding, and the extruder was jammed solid. It's happened before, and I took the lazy way of clearing it -- that is I cranked up the heat and turned off the cooling fan while retracting 20mm of filament, then extruding 25mm of filament, until the extrusion forced new filament into the melted mess, and pushed the jam out the nozzle. No dice this time.

So... I pulled everything apart, and discovered that the "melted mess" had gone up a bit further, into the heat isolation part. (Looks like a short ceramic barrel) which wasn't getting hot enough to melt out.

I suspect that the barrel below has worn, or is oversize to the point where melted plastic is coming back up past the barrel when extrusion rates are slow (Like extended low-speed extrusion for "small borders" over many layers) which would explain why small surfaces often look like they're under extruding when I know that I've got my steps per unit dead on.

Anyway, I left the ceramic and the nozzle of the hot end in a jar of acetone (Good use for old salsa jars!) Good thing it happened using ABS and not PLA, I guess...

---

MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

The material itself doesn't have to creep up into the heat break. If the heat works its way into the heat break the clean filament in the heat break will become melted mess, as you eloquently put it. Make sure the hot end fan runs at all times and you're getting good airflow over the cold end or cooling block, whichever your configuration has.

Any picture of the extruder ?

---

Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

I think we need a section covering cold zone cooling. I added this 40x40x20mm fan (see pic) and haven't had a jam since. Cools the motor extremely well. Good luck.

The hotend came with a fan that pointed in the general direction of the nozzle. I've added a shroud to it to keep airflow away from the heat block, as it seemed counterproductive to use a fan to cool the heat block, while applying power to heat it up.

Anyway, the acetone cleaning was a great success, and when reassembling my hotend, I managed to tighten up a couple of problem areas that was allowing the nozzle to move relative to the print head. the result is that my prints are MUCH better now. Holes in particular are much less random in effective diameter.

My shroud was done in tinkercad: [www.tinkercad.com] it mounts to the bracket holding the extruder to the X/Z carriage, and holds a 40mm fan very nicely. Probably not extremely useful to anyone with a different extruder, but it does an excellent job for me. I printed it in ABS plastic, it hasn't had issues with melting close to the heat block, which I was somewhat concerned about.

I don't have a good picture of the extruder. I was very discouraged with the results I was getting, but after the last set of adjustments, the new shroud and general adjustments, I may not use the E3D V6 hot end that I'm waiting for right away. It may end up on a new printer instead.

Lol... 3d printers are an addiction... I've got a few spare M3 screws... I need to build another printer!

Congrats on getting yours sorted out...

LOL yeah.

Well, in my case, I don't have ANY spare M3 screws... But I have a bunch of LM8UU bearings, stepper motors, a hot end, most of an extruder, Arduinos, RAMPS boards, stepper drivers, etc. My main idea for building a new one though would be increased rigidity and improved resolution, making higher precision parts possible. A larger print bed area would also be nice, but I'd like to try for precision rather than volume next.

For larger parts, it makes more sense to use a cnc router, which is also a project on the go.