Pig Tailing Hot End - Out of the Blue - No Issues Found

Alright, I could use some help here people.

Part of my pre-print routine, is to heat the hot end up, and extrude plastic out and let it hang, usually having it fall off as the hot end cools. I do this because back in my Mini days, if you didn’t prep it like this sometimes, it may miss a first layer. Also heating it I take a paper tower and wide down the hot end, getting any excess filament that’s.

Well the other day I went to do this and it started pig tailing bad. No room for error or anything just shoots backwards. It didn’t do this the previous print.

Now I am running a Lulzbot Taz 6, with the original Single Extruder head (which I love). Running Inland PLA (the same spool for awhile in fact)

I went ahead and proceeded to do a hot pull, did pull out some stuff, then did some more hot pulls and cold pulls. They all came out clean, however, even the cleaning filament would keep pig tailing, despite all the pulls coming out clean. I went ahead and scrubbed the hot end down with a green scrubby pad, no luck. I went and wiped it down with Isopropyl alcohol, no luck. Shoot one of the cold pulls I put the sucker up to 260 C to try and bake stuff out. Another time I pulled the fan off for a short bit (a trick support had me do to my SL, so thought I’d try it here)

None of my cleaning tricks are working, and what’s weird is this just happened out of the blue, and it doesn’t matter the filament, it’s pig tailing.

At this point, I am tempted to do a print to see if it jogs something lose, but at the same time, I’d rather not waste the time, filament, and potential mess, since, it seems it would do no good, when I can’t even extrude it regularly.

Could use some help here, because I’m out of ideas, and all my other tricks aren’t working anymore

Pig tailing is almost always caused by a dirty nozzle but if you have done cold pulls with cleaning filament, don’t get anything out, and it’s still pig tailing then perhaps a damaged nozzle?

The nice thing about the Single Extruder head is that the filament path is straight. I can shine a light in the top and see a nice round light (using a mirror) at the bottom when mine is clean.

I bought a set of micro mm drill bits (two sets actually as bits this small can break easily) and carefully use them by hand to clean the nozzle opening. Another choice might be https://www.amazon.com/dp/B07M66QHQF.

Last but not least would be a new nozzle.

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Yeah I will admit looking at those tools just look like an issue for me (like I don’t have the confidence for it). I also know I have to be careful, reading stories of people who shorted out their autoleveling sensor

I will give the flashlight a trick, may not have the mirror but I got a good eye.

And yeah, I was thinking on the nozzle. Only problem, I have no clue where to get one or how to replace it (they don’t make that super clear). Got any advice, tips, ext for this?

Shorting out can happen when you use a conductive object (like a brass wire brush) and you leave the power on after heating the nozzle to clean it off. Heat, turn off, brush, turn on, repeat as necessary or use a non-conductive abrasive like Scotch Brite pads.

I don’t think you can raise the nozzle high enough to get your head inside the printer to look up the nozzle opening :grin:. I use a cheap convex mirror I bought at the grocery store. Also useful for just looking at the nozzle to see if it needs cleaning.

If you don’t feel comfortable with the tool idea, you can get a replacement nozzle from https://itworks3d.com/?product_cat=0&s=hexagon+nozzle&post_type=product. As for how to change it, try https://forum.lulzbot.com/t/howto-change-hexagon-hotend-nozzle/2613.

Nozzle, nozzle, nozzle. I just ran through this ad nauseam. I removed and soaked the nozzle in lacquer thinner and cleaned it; even though I could see through it the problem remained. I ordered a replacement nozzle and as a last ditch effort while I was waiting for the nozzle to arrive I pulled the old one out again to see what I could do.

After soaking and cleaning, this time I took a #31 drill (just over 3mm) and recut the nozzle internal seat where it transitions to the actual nozzle size. I also very carefully sanded the flat on the nozzle exit and deburred the hole with a slightly larger drill bit. It works just like a new nozzle!

Pro Tip: dig around the junk drawer for stranded copper wire, find a single strand that measures 0.5 or just under the size of your nozzle. (Each strand may be different sizes). Poke it up into the nozzle when hot to dislodge any stuck debris.

I HAD bought the drill bits but they broke easily. I also bought the cleaning needles, but the wire strand was free and disposable.

Make sure there are no tiny burrs / damage to the nozzle. It’s not too difficult to replace just the nozzle. Check for videos before you did tho.

I already did do some cleaning of the outside with a green scrubby pad, and that didn’t seem to help. Might go back in and do some more though. But I didn’t heat it too much, since the heat would eat through the pad (only metallic like I have is steel wool, and don’t want to use that, too abrasive).

I might lean the route of the nozzle, since I love this head and don’t want to risk damaging it (since they don’t make it anymore).

Push comes to shove, I could switch over to my SL, I just don’t like it as much as I have to use a little more expensive PLA (Inland PLA+ to be specific), and I HATE how you load/unload it.

As for looking inside, I have been actually looking to get a fiber optic camera for some other projects around the house. Maybe this is the push I need to buy it. Could easily feed that in and see what’s up. Course, another trick, is shine a light from the bottom up, helps a little

I probably don’t have the steady enough hand for this (or tools). That is quite ambitious though. Feel like buying a new would just be easier LOL

As long as power is cut right? So you don’t short the auto leveling

You can use a brass wire brush by heating the nozzle, turning the power off, and then brushing the nozzle.

Instead of turning the power off, I’ve protected myself from the potential shorts by adding some high temperature silicone (Permatex Red RTV High Temp Gasket Maker #81160) to the wires as they enter the heater block.

The root problem is that there is burned on residue at the transition in the nozzle. Even if you clean the opening with a wire the residue will remain. I repeatedly removed my nozzle and soaked it in lacquer thinner and could see through the opening but the problem persisted. It wasn’t until I cleaned the transition with a #31 drill that the problem went away.

If you’re unwilling to remove the nozzle and clean or replace, your only hope is to do a cold pull cleaning repeatedly. Instructions below.


"One of the most reliable ways to remove a clog, especially one caused by a significant amount of melted filament, is to do a “cold pull” using another filament. A nylon filament is the best option for this method due to its high melting temperature. ABS is also a good, and far more common, alternative.

To do the cold pull method, you need to dismantle the extruder setup to allow you manually push a filament through the nozzle. Start by heating the nozzle to 250 °C and leaving it at this temperature for about 5 minutes. Firmly but gently, push the nylon (or ABS) filament through the nozzle. At the temperature of the nozzle, the previous filament that had caused the clog should be completely melted and extruded along with the nylon. Continue doing this until you no longer see any of the old filament coming out with the nylon.

Allow your nozzle to cool down to room temperature so the nylon filament can re-solidify. After this, heat the nozzle up to 120 to 130 °C. This will be just hot enough for the filament to soften so you can pull it out completely. Give the filament a solid yank out of the nozzle. This should leave an impression resembling the shape of your nozzle on the end of your filament. Any dirt or loose materials that were not pushed out in the first part of this process should come out with the cold pull.

You can do this process several times if you can’t get all the leftover material in your nozzle on your first go. If you find pulling out the filament too hard on your first try, then you can try higher temperature settings for the cold pull step." Quote from https://3dinsider.com/cleaning-3d-printer-nozzle/

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Here is a video snippet that will give you and overview of a cold pull.

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Wow I have been doing my cold pulls all wrong.

I will say this last weekend I went and heated it up hot, way hotter then ever before. Did some cold pulls (because I noticed stuff in the hot end). What I found interesting is if extruded normally, nothing, but when I pushed the nylon through, all of a sudden black plastic came out.

I’ll try this approach, might be why I am having issues, cause I haven’t been doing it right (I usually let it stay hot for a min or less).

Wanted to do a follow up with this. I ended up contacting support, as I realized I had a valid warranty still for the printer, and after a few not so successful emails I called, and the rep on the other line got me hooked up with an RMA (she asked the gurus and they confirmed it was the nozzle).

Anyway after a few weeks just got it back.

Sadly, while I’m grateful they worked on it, the nozzle I got back appears used (it’s got that layer of brown on it with dark spots, and the cube above it has dried plastic on it, almost like this came off a printer they had laying around form the look of the colors on it)

They may have just tested it after installation.