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I have an old custom 3D printer that I bought a new hotend for since the old one broke, and apparently, I made a mistake.

The old hotend had insulation on it that prevented it from melting the mounting point on the printer itself, but the new one is all metal.

When I heated up the new head for the first time it melted the mounting point and fell out.

When is the best solution for my case?

Is there some insulation I can put on the new head? I can't find another insulated head anywhere.

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    $\begingroup$ Adding photos of the old and new hotend could be beneficial for answering the question. $\endgroup$
    – 0scar
    Apr 14 at 19:45
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    $\begingroup$ As stated, photos would help us understand better... couldn't use reuse the insulation from the old hotend, i.e. cannibalise it? $\endgroup$
    – Greenonline
    Apr 16 at 16:14
  • $\begingroup$ I assume that the mounting plate is plastic (hopefully metal isn't melting), but this may be good information to include. Does your hot end have a cooling fan? Usually the heat break has a fan. Perhaps this could help (though I doubt it). $\endgroup$ Apr 16 at 18:15

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Hotends need insulation. Not just to prevent melting the mounting bracket, but:

  • To prevent heat loss to the air, especially with part cooling fans active, that could reduce the ability to heat or even trigger thermal runaway protection from complete inability to increase temperature beyond a point.

  • To prevent dumping heat on the printed part, which fights with your part cooling fan and greatly diminishes its effectiveness.

At the very least, the heater block needs a silicone sock. You can also use high temperature ceramic fiber or "rock wool" insulation like you'd use for an oven or kiln, and/or just layers of aluminum foil (which reflects a lot of the heat, while air pockets between layers provide insulation).

To find an appropriate sock for your hotend, search for its model name together with "silicone sock". You can also make your own using high-temperature RTV silicone (for example Permatex 81878) and a mold if you have a block with odd dimensions that nobody seems to be selling socks for.

In your question you mentioned "all metal". In the context of hotends, "all metal" generally doesn't mean that there is no non-metal insulation or other material attached or that it's not okay to attach such, just that there is no PTFE or other material that can't handle high temperatures in direct contact with the hot parts. It's perfectly reasonable (and necessary) to put proper insulation on an all-metal hotend.

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  • $\begingroup$ depends... you can safely mount the coldend of the hotend (aka cooler body) to a plastic mount, if the cooling body below properly gets rid of the heat - such as in the e3D v6 design $\endgroup$
    – Trish
    Apr 16 at 8:24
  • $\begingroup$ @Trish: If the plastic is something that can withstand at least some minor warmth, and the hot part is sufficiently far away, I think you're right that it will work. But I still maintain it's a bad idea to run without insulation, regardless of whether (but especially if) you have a plastic mount. It will harm your printing performance (as described in my answer) and it probably makes failure conditions somewhat more severe. $\endgroup$ Apr 16 at 13:17

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