Hotend jammed

I have been banging my head against the wall for days in this issue with my Tax… I have completely disassembled my hotend, cleaned it and put it back together 3 times… It extruded the ABS for maybe 20 seconds and jams again… What am I doing wrong…

Depends on how it is jamming. if it’s grinding a “C” shaped notch in the filliament, you either have the nozzle too close to the bed, crap filliament, or potentially but unlikely a blocked nozzle or a bad thermistor / heater cartridge. Get a cheap infrared thermometer from your local auto tool store or hardware store and check the temperature the nozzle is at vs. what it says it is at in the software. If that’s close, it’s probably not an electronics issue. Move the nozzle up 20mm off the bed and see if you can get it to extrude without stopping away from the bed. If it does, you are too close to the bed when trying to print. If it doesn’t, check the spring tension, and also check the small gear on the extruder motor and make sure the set screw holding it to the motor shaft is down and tight.

Also make sure you clean any shavings out of the filliament chamber and out of the teeth of the hobbed bolt itself.

You need to post more information regarding what you’re doing and at what settings.

What temps are you using? What filament are you using? Who makes it? What size nozzle? What software? Are you using Lulzbot supplied configurations for ABS? Maybe your print speeds are WAY to fast?

Before I even hit the print button I typically have a small strand of ABS oozing out of nozzle.
I use Slic3r and Pronterface.

I print at 230c for nozzle temp. I usually set that temp and then wait for a good 10 minutes before I start to print.

Above suggestions are good. Also, make sure you actually cleared out the jam. Maybe correct temp, extruder tension, etc can get your extrusions going again, but if not you can often clear out a clog that can’t be extruded out by dismounting the hot end and heating it up while it’s resting on some glass. Carefully pick up the aluminum mounting plate with some pliers (because it will be hot) and push the 2.5 mm Allen wrench down through the hot end until you see a good flow of material coming out the tip. If the Allen wrench can’t push out the clog you may have to take the nozzle off to get at a plug of plastic. Also, at this point get a 0.3 mm drill bit or smaller and push it up through the tip to make sure there isn’t some foreign debris stuck in the tip.

Before I’d be drilling, or trying to force stuff through a HOT nozzle, I’d drop nozzle into a glass/beaker of acetone and let it sit overnight. Completely submerge nozzle and cover glass with something to prevent evaporation.

I’ve cleaned out a nozzle this way and it works wonderfully.

Take great care and caution removing nozzle and replacing it.

Super easy to destroy threads. Follow instructions in manual.

Just found this to illustrate the drill through the tip technique:

You do want to be careful not to scratch the metal surface of the tip if you try this; otherwise it could affect the extrusion quality.

If you have time, soaking the tip would be a better first option as edlink described because you eliminate the possibility of scratching the tip by soaking. Personally, I had a clog from HIPS and soaked the tip overnight, but there was still something blocking it so I used a micro drill bit to punch it out; although soaking may have made it easier to punch out whatever was there too.

I concur with Edlink drill bit should be your last resort. A soak in acetone is alot short and cheaper than waiting for the new parts to arrive from Lulzbot. I used to be a man of many jams and I never used a drill bit and still managed to destroy several components.

The majority of my jams are limited to:


Also it should be said that I only had to deal with 4 & 5 because I messed up taking a part my nozzle when I didn’t need to on 1-3. :blush:

What filament are you using? (Cause of many jams)

What temperature are you at? (You might need to up the temperature by 5 degrees)

When it jams is it chewing thru the filament? (If so did you clean out the little teeth

Does it still jam in the same amount of time if you just have it up and extrude into midair? (This would indicate that it is not solely due to bed leveling)

Are you checking the leveling while its cold or hot? (Metal expands when ti gets hot and it can screw up your nozzle to bed spacing.)

If you insist on taking apart nozzle. I recommend you put some spark plug anti-seize on when you put it back together. They sell little packet of this ( at most autopart stores . Like Edlink said its easy to mess up and you probably won’t realize you fused them till you try to take it apart next time.

If you want you can check out some my mistakes here:

+1 on letting the nozzle sit disassembled in acetone overnight. I had a nasty jam once and that helped tremendously. I still have to clean out some bits with a thin needle and more acetone but then it printed like a jam again.

As to what is causing these clogs I’m sure more experienced users can help you more…

This helps a lot. Just had a similar situation with a brand new replacement hot end…

here’s my thread…