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I put a new glass bed on my Ender 3. After playing with the baby-steps and bed temperature I thought I had it ready to go. I started to print some rocket kits for the Cub Scouts and the job didn't stick. I ended with a giant blob on my hot end. I thought I cleaned it up, made some more adjustments and started again. I watched it this time and noticed some times I had under extrusion, other times over extrusion, a sometimes perfect extrusion. Since I just upgraded to a new metal drive for the extruder and that looked good I decided to look at my hot end. Here is a pic of what I found. enter image description here

I think my Hot End is now toast. Any suggestions on how to fix the hot end?

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    $\begingroup$ Welcome to 3DPrinting.SE! Please note that this is a hardware recommendation question, such questions attract very opinionated answers and therefore should be closed. This question can be saved if you have no idea which hotend this is and what type it is or how it is called - and you require help identifying the hotend. Please edit the question as such. $\endgroup$
    – 0scar ♦
    Jun 24, 2021 at 22:30
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    $\begingroup$ If the feed tube fell off, it would be unhosed, requiring you to rehose it. (Sorry, coudln't help it.) $\endgroup$
    – user10489
    Jun 25, 2021 at 5:03
  • $\begingroup$ This looks a lot like you didn't do hot tightening properly. you have to heat up the end to above printing temp, then tighten the nozzle and then let it cool, the difference in the coefficient of expansion of the metals then causes them to seal against each other. This is not optional and can't be replicated just by tightening harder, the expansion/clamping is vital to prevent this sort of leak... $\endgroup$
    – John Meacham
    Jul 3, 2021 at 4:50
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    $\begingroup$ Hi @JohnMeacham - please could you post your answer as an answer. Comments are intended for requesting clarification only and are ephemeral in nature and tend to be deleted. Also, answers in comments can not be ranked by votes. Comments are not recommended for any of the following: Answering a question or providing an alternate solution to an existing answer; instead, post an actual answer (or edit to expand an existing one). Feel free to post an answer instead. Thanks. $\endgroup$
    – Greenonline ♦
    Jul 3, 2021 at 17:47
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    $\begingroup$ @user10489 - please could you post your answer as an answer. Comments are intended for requesting clarification only and are ephemeral in nature and tend to be deleted. Also, answers in comments can not be ranked by votes. Comments are not recommended for any of the following: Answering a question or providing an alternate solution to an existing answer; instead, post an actual answer (or edit to expand an existing one). Feel free to post an answer instead. Thanks. $\endgroup$
    – Greenonline ♦
    Jul 3, 2021 at 17:49

1 Answer 1

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This is filament leakage. It's generally due to the nozzle and heat break not being correctly tightened against each other (if you've ever disassembled or upgraded the hotend you'd have needed to do this).

Presuming that you can heat the hotend and (carefully -- extrusion temperature is close to that of a medium-hot oven!), peel off most of the mess, and get it disassembled, you should then be able to finish cleaning up and correctly reassemble.

You need to install the heat break into the heat block, heat to 20 °C or so above your highest printing temperature, then tighten the nozzle against the heat break. If the nozzle bottoms against the heat block before coming tight, you'll need to back it out, screw the heat break in another turn or two, and tighten the nozzle again. Let everything cool, then reheat and retighten the nozzle.

N.B. Do NOT use teflon tape, pipe dope, or anything else on the threads of either nozzle or heat break: these threads need to have metal to metal contact for heat transfer, and the seal is between the nozzle face and heat break face, not the threads in any case.

After everything is cooled again, you can finish reassembling the heat sink (if you had it off during the nozzle installation), silicone sock (which should replace the kapton taped insulation wadding your photo shows), shroud and fan -- and you should then find you've stopped the melted filament leaking around the heat break threads as in your photo.

And no parts needed!

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  • $\begingroup$ "new metal drive for the extruder" doesn't seem to mean all-metal hotend. Most likely replacement of Creality's cheap plastic tension arm with a metal assembly. $\endgroup$
    – R.. GitHub STOP HELPING ICE
    Jul 2, 2021 at 3:10
  • $\begingroup$ I have both the "metal extruder" -- supplied by Comgrow (Creality's sales organization, at least for Amazon sales) under warranty after my plastic tension arm cracked -- and a "metal hot end" that, as claimed, has no non-metal parts, but still runs the PTFE tube all the way to the nozzle. My machine came with a silicone sock, however, leading me to think OP got a knockoff or an older machine. $\endgroup$
    – Zeiss Ikon
    Jul 2, 2021 at 11:27
  • $\begingroup$ OP didn't say anything about having replaced the hotend. A hotend where the PTFE runs all the way to the nozzle is NOT an "all-metal hotend". All-metal means that all the parts that get hot are metal, and other materials (if any) are across the heatbreak on the cold side. Further, from the picture OP's hotend (what we can see of it at least) looks exactly like Creality's stock hotend. $\endgroup$
    – R.. GitHub STOP HELPING ICE
    Jul 2, 2021 at 14:06
  • $\begingroup$ @R..GitHubSTOPHELPINGICE Agreed, hence my edit to remove reference to replacing the hotend. The primary distinguishing feature of "all metal" hotends is the PTFE tube (present with either Bowder or "direct drive" extruders) contacts the cooled end of the heat break, vs. going all the way to the nozzle in the original Mk. 8 hotend. $\endgroup$
    – Zeiss Ikon
    Jul 3, 2021 at 16:30

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