1 Topic by beavertank

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Topic: Leaking hot end?

As I sat down for a soothing evening of printing I noticed something worrying. There was a new bit on my hot end... It looks a bit like slightly overcooked plastic, and was (at the time - when the hot end was at temperature) squishy.

You can see it in the attached photo, it's the bulge between the top of the heat wrap and the PTFE tube. As the print kept running it seemed to be (very slowly) growing, so I panicked a little and killed the print.

I've seen or heard of other hot ends needing "sealing" where the user runs some plastic through it, lets it ooze, then lets it cool, and the previous ooze seals the leak. But I've had this printer for a couple months (and have maybe 175-200 hours of print time on it) and this is the first I've seen of it.

I changed from my cracked acrylic jigsaw to the replacement cold end a few days ago, but I've been printing since then and this bulge only appeared this evening.

If I let it cool down and solidify will I be safe to bring it back up to temperature and keep printing? If it keeps leaking will I have to replace the hot end entirely?

I don't feel safe running the five hour print I had planned now, which is extremely annoying. Am I overreacting by killing the print and keeping it cold for now?

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2 Reply by danny

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Re: Leaking hot end?

I assume you've been printing brown/gold and this is that plastic?

if you let it cool then you won't be able to remove the nozzle from the brass barrel.

the only way I could clean my nozzle when I had this leaking problem was to take the barrel off the machine and leave the heat core connected.
then heat up the brass barrel so that the plastic is soft, then turn it off and unscrew the nozzle whilst the plastic is soft.
the same will be true of cleaning all the crap plastic off of the heatcore. when the plastic cools it'll make any threaded part impossible to unthread -you'll likely break the brass barrel of unscrew the peek trying to undo this! you have to heat up the barrel to remove it.


once you've cleaned it then you need to re-assemble the barrel and make sure it's tightened well.

letting plastic ooze will not seal the leak because when it gets hot the plastic gets soft again and lets more come out

3 Reply by beavertank

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Re: Leaking hot end?

danny wrote:

I assume you've been printing brown/gold and this is that plastic?

I was actually printing in red, but I think the color is because it must have spent a long time being cooked against the heater before finally oozing enough to become visible.

Looks like I'll be pulling the whole hot end apart then... Here's hoping I don't destroy it.

Why would it suddenly leak like this when it has worked fine for so long?

4 Reply by IanJohnson

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Re: Leaking hot end?

Maybe the PEEK got too hot once and the threads deformed enough to loose their seal.

5 Reply by beavertank

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Re: Leaking hot end?

Yeah, that's what it's looking like happened. For some reason I thought the ooze was coming from the nozzle area up past the heater core and then leaking out around the top edge of the elastic insulator. After pulling it apart (luckily without serious incident) it seems to have been a small leak between the brass threaded tube and the PEEK.

I attached another photo showing the now solid layer of formerly molten plastic inside the PEEK tube, is this normal? Should I make some effort to clean it out before reassembly?

I'm assuming at this point my best bet is just going to be carefully reassembling the hot end and hoping it doesn't leak again with the oozing plastic all cleaned out, but while I've got it apart is there a better location for the thermister than kapton taped against the nozzle? I seem to remember running across a discussion about how the temperatures we were getting from that location was somewhat deceptive and that moving it might help, but I don't know where else it would go and can't find that discussion again.

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6 Reply by solijohn

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Re: Leaking hot end?

beavertank wrote:

Yeah, that's what it's looking like happened. For some reason I thought the ooze was coming from the nozzle area up past the heater core and then leaking out around the top edge of the elastic insulator. After pulling it apart (luckily without serious incident) it seems to have been a small leak between the brass threaded tube and the PEEK.

I attached another photo showing the now solid layer of formerly molten plastic inside the PEEK tube, is this normal? Should I make some effort to clean it out before reassembly?

I'm assuming at this point my best bet is just going to be carefully reassembling the hot end and hoping it doesn't leak again with the oozing plastic all cleaned out, but while I've got it apart is there a better location for the thermister than kapton taped against the nozzle? I seem to remember running across a discussion about how the temperatures we were getting from that location was somewhat deceptive and that moving it might help, but I don't know where else it would go and can't find that discussion again.

We're you able to get everything back up and running?

Former Solidoodle employee, no longer associated with the company.

7 Reply by beavertank

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Re: Leaking hot end?

solidoodlesupport wrote:

We're you able to get everything back up and running?

Sort of. I got everything reassembled but the thermistor apparently shifted significantly and the actual hot end temperature was about twenty degrees higher than before (so when I fed it 200c in software the hot end was closer to 220c). I also had severe oozing issues, when extrusion stopped it would continue to ooze at basically full extrusion speed for about 15 seconds. When printing this led to such severe errors that the printer was unusable.

I pulled it back apart and shifted the thermistor to where I thought it should have gone and unscrewed the brass barrel from the PEEK slightly (thinking I had screwed it too far in last time and this was related to the oozing issue). The temperature seems to be closer to correct, but I still have serious oozing. It has improved, but not enough to really be usable. Now when extrusion stops it oozes for about five seconds, and the oozing is slower than full extrusion speed, but still produces enough ooze to make printing basically impossible. I haven't had a lot of time to fiddle with it for the last week or so.

Before the leak around the PEEK tube and this disassembly my hot end would ooze about 2mm of extrusion as it heated up, but wouldn't ooze during printing and would stop extruding when the extruder quit pushing filament. I know you guys have been looking into why some print heads ooze while others don't, do you have any suggestions on how to fix my oozing problem?

8 Reply by devilman2075

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Re: Leaking hot end?

Typically the solidoodle already reads off from the factory. Normal abs printing temps seem to be around 215c-230c sometimes a little higher. Our 195-200 basically ends up around 225-230ish.

9 Reply by beavertank

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Re: Leaking hot end?

devilman2075 wrote:

Typically the solidoodle already reads off from the factory. Normal abs printing temps seem to be around 215c-230c sometimes a little higher. Our 195-200 basically ends up around 225-230ish.

I understand that, but the actual temperature isn't really the issue. If my thermistor was reading off by 20 degrees after reassembly I could just adjust for that in the settings I'm using.

The problem I have, and the reason I took the hot end apart again (and the reason I'm currently unable to print), is oozing. The hot end oozes so badly after the extruder motor has stopped that any printing attempt is ruined.

10 Reply by Tomek

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Re: Leaking hot end?

I ended up switching PEAK barrels for different reasons, but my old one would ooze and I discovered the bottom half of the threads were smooshes because I'd ran over temp too many times. Perhaps tat is the problem, if you're talking about oozing from the threads.


If you're talking from the nozzle, then I'll note when I switched from .35 d nozzle to .4mm, I got more oozing. This is to be expected, and for me was a worthwhile drawback.

11 Reply by beavertank

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Re: Leaking hot end?

Tomek wrote:

I ended up switching PEAK barrels for different reasons, but my old one would ooze and I discovered the bottom half of the threads were smooshes because I'd ran over temp too many times. Perhaps tat is the problem, if you're talking about oozing from the threads.


If you're talking from the nozzle, then I'll note when I switched from .35 d nozzle to .4mm, I got more oozing. This is to be expected, and for me was a worthwhile drawback.

The threads on the PEEK tube all looked intact the two times I disassembled it, and that's not where the ooze is coming from now.

Now it's as if the printer continues extruding for about five seconds after the extruder motor stops. I'm still on the .35mm nozzle too. I haven't touched that.

12 Reply by solijohn

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Re: Leaking hot end?

beavertank wrote:
Tomek wrote:

I ended up switching PEAK barrels for different reasons, but my old one would ooze and I discovered the bottom half of the threads were smooshes because I'd ran over temp too many times. Perhaps tat is the problem, if you're talking about oozing from the threads.


If you're talking from the nozzle, then I'll note when I switched from .35 d nozzle to .4mm, I got more oozing. This is to be expected, and for me was a worthwhile drawback.

The threads on the PEEK tube all looked intact the two times I disassembled it, and that's not where the ooze is coming from now.

Now it's as if the printer continues extruding for about five seconds after the extruder motor stops. I'm still on the .35mm nozzle too. I haven't touched that.

Just as a warning, we do not recommend that anyone removes their PEEK insulator from the brass tubing. Once the Solidoodle heats up, there is a good chance the threads in the PEEK have permanently bonded to the brass. That means any removal is risking damaging the threads.

Former Solidoodle employee, no longer associated with the company.