Kicked off the second long print in a series (printing Lack enclosure components). First 10 hour print was flawless. Started this one, saw the first layer laid down well, went to bed. Woke up to this (you can see the successful prints in the background):

enter image description here

The whole heater block and nozzle is entombed in PLA. The leads to the heater and the thermistor are too. I'm assuming there's no solvent for this, and I'm better off just buying a new hot end.


  • 1
    $\begingroup$ Wow, that's just ugly! ;-) I think this is going to be situation dependent solution ... If I were you, I'd just see if I could start removing filament a chunk at a time. If you can get them cleared, all the better. If you can't without destroying the hot end parts, back to the drawing board. You'll need to get the mess cleared before you can get new parts on there anyway, so might as well have at it. The real question here is, why did it putz up?? ... I guess the tape is a good indicator here. $\endgroup$ – Pᴀᴜʟsᴛᴇʀ2 Feb 12 '19 at 19:08
  • $\begingroup$ i think the tape looking that way is a consequence, not the cause. not pictured is a piece of the print that was on it originally, found next to the bed. whenever it got knocked off, it took the tape with it. $\endgroup$ – kolosy Feb 12 '19 at 19:33
  • $\begingroup$ Pull out the Dremel and have at it, I'd suggest? $\endgroup$ – Pᴀᴜʟsᴛᴇʀ2 Feb 12 '19 at 19:36
  • $\begingroup$ @Pᴀᴜʟsᴛᴇʀ2 Only if you don't value your hotend... or know exaclty where it is. Heat and pull down. $\endgroup$ – Trish Feb 12 '19 at 20:16
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    $\begingroup$ @kolsy, wow make it even more amazing. Wish we had time lapse of that blob forming. $\endgroup$ – user77232 Apr 22 '19 at 1:00


I had a somewhat similar clog once, and I could fix it back up. However, it is a lot of work.

Hobbyist Way

Step 1: heat

As long as the heater cartridge is still ok, just fire up the printer, move up the print head by 50 mm and wait some two or three minutes till the goop is warmed enough at the core to melt. Set the hot end to 200 °C and no cooling fan.

Step 2: rough clean

Check the cables for your hot end and thermistor as long as the plastic has not yet softened up around them and especially surrounding the thermistor: When the glob is removed in one swoop, you might tear the lines! It's better to use a sculpting tool or exacto-blade on the softening plastic and make an opening that allows the glob to be pulled away safely with minimal pull on the cabling.

When the blob has softened enough, you can just pull at the outer of the blob to pull it down. Use a tool like pliers and pull off the worst that still sticks to the hotend. Pulling the blob free can take a while, so be patient and careful.

If you have a soldering iron, you can use that as a heated scraper from the outside and skip on heating from the inside. If you have no temperature control (as if your thermosensor is shot) outside heat is the only safe way.

Step 3: Cool down

After having made a rough clean up from the outside, let it cool down so you can dismantle it.

Step 4: dismantle and clean the hotend.

This is actually rather simple, and I will point to a question where I outlined that for a broken thermistor cartridge. You have a working thermosensor at least, so less problems on that front.


If you have a hot air gun for hot air soldering, you can be much faster! Skip step 1 to 3, dismantle the hotend and go straight to Step 4, dismantling it and cleaning it out of the machine with the hot air soldering tool as a heat source. Heat and scrape away, and get out the thermosensor and thermosensor as soon as possible to prevent destroying them.

  • $\begingroup$ Can a hairdryer substitute for the hot air gun? In my experience it's plenty hot to soften PLA to let you deform/reshape it, but I'm not sure how helpful that'd be in removing it. I would think a hairdryer would be safer to avoid damaging the printer in the process. $\endgroup$ – R.. GitHub STOP HELPING ICE Feb 7 '20 at 1:44
  • $\begingroup$ @R..GitHubSTOPHELPINGICE In a pitc, probably, but you want to melt an awful lot of plastic... a typical hairdryer gets 140 °F = 60°C, enough to make PLA somewhat malable on the surface. A hot ar gun gets considerably more - 350 °C is usually a given. $\endgroup$ – Trish Feb 7 '20 at 16:19

Careful application of a hot air gun, along with mechanical prodding (pliers, pokey sharp stick tool) will soften the PLA. It will soften on the outside but the heat transfers inward rather easily and quickly and is retained for some time.

When heating and poking, force the mass downwards and then away from the heater block. If the outside becomes liquid, too much heat is being applied and may damage other components.

An SMT soldering station with adjustable temperature and airflow rates would be ideal, but a garden-variety hot air gun with a concentrating tip could be used effectively.

  • $\begingroup$ hot air... is a solution but not while the printhead is installed - you'd burn the other parts to smithereens. $\endgroup$ – Trish Feb 12 '19 at 20:17
  • $\begingroup$ Yeah, I have an SMD rework station 2 feet left of the printer :) $\endgroup$ – kolosy Feb 12 '19 at 20:19
  • $\begingroup$ @kolosy If you use that, first dismantle the hotend. $\endgroup$ – Trish Feb 12 '19 at 20:22

If you can remove the hot-end it is easier. If not, carefully use hot air to soften (not melt) the PLA so you can more easily pull away chunks.

When the hot-end is removed from the other plastic parts, you can get more aggressive with hot air. BUT, be careful of the thermistor and heater wires. They are fragile, and can easily be broken or pulled out of their devices.

Heat and patience is the key. If you do break a heater or thermister, they are pretty easy to replace. Depending on the hot-end, the heater and/or the thermister may be locked in place by a set screw. That set-screw is probably locked in place by plastic, so use the hot-air gun to melt that plastic and allow you to back out the set-screw.


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