Efficient and easy way to thermally insulate the heat block of the hotend?

  • Sparked by this question, I wanted to discuss the most efficient and also the easiest ways of thermally insulating the heat block of the hotend.

    I have seen Kapton tape insulations as done here with a very conclusive resumee about its usefulness.

    In the links of the named article, a method with insulating material from a heatbed is described, however without giving quantitative results.

    Additionally, I know that in the guys over in the german reprap forum produce their own silicon covers for the heater block. As I understand there is a large spread between people's reports, from 'almost negligible' as insulator (but helpful for other things) to very useful. No quantification, though. Also, these seem to come with a certain amount of effort to produce.

    Are there additional solutions and/or comparisons between solutions?

  • The "quick and dirty" approach is to just slap a bunch of Kapton tape on there. The more the better! (Until you need to dismantle for maintenance, anyway.)

    I find pre-cut ceramic tape + kapton tape "blankets" to be easy and effective. E3Dv6 and Replicator 1/2 style hot blocks should be compatible. Or you can cut your own using a sharp hobby knife.

    enter image description here

    The main downside is that they don't insulate two sides of the hot block. But covering the top and bottom provides much of the practical benefit, and you can always add a few more wraps of Kapton tape to cover up the rest of the surfaces.

    Another good option that has recently started to become popular is fiberglass heat shield tape. It has a silicone adhesive, woven fiberglass mat, and shiny aluminum surface. (The reflective surface reduces heat radiation.) It's often used in automotive applications around mufflers and the like. You can cut it up into little rectangles for each side of the hot block, or wrap the block similar to Kapton.

    enter image description here

    Main issue is quality -- not all brands have adhesive that will hold up to high temp printing. It may smell when initially "burned in" due to the adhesive cooking a bit. I also find that you need a couple layers to get as much insulation as the ceramic+kapton blanket when there's a lot of airflow around the hot block.

    I know it's a bit OT but i use this second material under my heatbed which increased a speed of heating up HB more than 2 times

    Oh yeah, I do the same thing. Works great for heatbeds in unenclosed printers. (I WANT the heatbed in my enclosed printers to heat the air!)

    These premade kapton insulators with fiber look good. Do you have any quantitative results like heat-up curves with and without such an insulation? This and also the fiber material given in you second solution are basically what is described in my second reference link, or do I miss something?

    If I'm understanding his description correctly, he used Teflon sandwich toasting bag material under the Kapton. I haven't personally heard of that. More common to see either the white ceramic tape or just multiple kapton layers.

    Did you ever make some quantitative measurements on your insulated heater block? Power consumption, pid temperature variation comparisons for example?

    Watching trends and power levels and stuff... not much quantitative logging. I got a 4-channel thermocouple package recently and plan to do some benchmarking of different hot ends.

  • I ask myself why people hassle with kapton tape when it is so easy to use teflon sealing tape to isulate the hotend. This tape is slightly foamed to allow better sealing when used for sealing "tube threads". It can be purchased anywhere for very little money and can stand up to 260° Celsius constantly and 300 ° for a short time (according to its data sheet) This shoud be sufficient for most applications. Water installation PTFE tape is very easy to apply because its soft and can be stretched to the right form. And it sticks for its own without extra glue. No hassle like with the stiff kapton tape. And the isolation is much better because of the air bubbles inside the tape. I did that on my extruder and it works perfectly. My extruder heats now up about 20% faster. I applied this tape in installed position within 5 minutes - easy !
    Teflon tape isolated extruder

    Welcome to the forum! I like your idea to use plumbers tape, and I'm sure I will try it. This answer doesn't directly address the OP's interest in comparisons, but it is on-topic. Could you improve the answer by comparing it with your experience using other insulating methods?

    Sounds like a great idea, but is there any issue with the toxicity of the fumes (even if no odor)? Just curious.

    @Questor , this is indeed an issue with PTFE tape: https://en.wikipedia.org/wiki/Polytetrafluoroethylene#Safety It starts releasing some non-great stuff at 200C, and increases with temperature. In the study cited by Wikipedia, the amount isn't worrisome until 250C, but this isn't a frying pan...we run these things at temperature in enclosed spaces for hours/days at a time. So I avoid PTFE in contact with the heater block, but it's in an abundance of caution.

  • I am using high temperature RTV. I just load it up and smooth it out like frosting a very small cake. I leave the top of the heater block clean and cover it with a piece of cotton insulation. I don't care about power consumption, I just want it to stay hot when the workpiece cooling fan comes on.

    I've had good results with "high temperature gasket maker", which is quite similar.(for example https://www.permatex.com/products/gasketing/gasket-makers/permatex-high-temp-red-rtv-silicone-gasket, good up to ~315C). Since you just squeeze it on and let it solidify, you can cover any shape, as thick or thin as you want. You can trim it or peel it all off if you need to later.

  • I just came up with my own solution before I read this discussion. (Monoprice Select v2.1 - Wanhao i3 Clone).

    I ~think~ I have a Mk8 hotend.

    I had some silicon rubber sheet (about 1.4mm thick) which started life as a cookie sheet, but I gave it a new purpose in life, LOL.
    I cut two pieces to length to wrap around the hotend, and made a double thick sandwich.

    I then used adhesive backed aluminum ducting tape* (SEE EDIT BELOW!!) (NOT duct tape, ALUMINIUM tape) and wrapped the sheets in it, then used needle nose pliers to shape it to fit the heater block. The aluminium tape helps it hold shape.

    I used 3M 468MP to tape it to the hotend, as I currently have no kapton tape.
    Just did this today, if I have adhesion issues I'll TRY to remember to report back here. :) If it does pops loose, I'll use a bit of stiff wire twisted around to support it.

    EDIT: Welllll ... sometimes one gets too clever for their own good!

    USING THE ALUMINIUM TAPE IS NOT A GOOD SOLUTION, DON'T DO IT!!! It seems the adhesive on that tape emits noxious, and perhaps POISONOUS fumes when heated! I had to vent the room to the outside for a couple hours with dual fans and the hotend at temp to clear the air! Ooops. LOL

    It's good now, it baked off.

    The idea DID work, and I'm sure would be fine if you use regular heavy duty aluminium foil. Be sure to mount it with the seam on the INSIDE and the 3M tape should hold it closed just fine.

    You can quantify the improvement by timing how long it takes to heat from cold to 90 degrees (with a target of 100, so there is no control loop input).

    @SeanHoulihane - Yeah, that makes sense, thanks. I noticed a huge improvement on the BED when I installed two cork sheets (with a notch cut to clear the wires) under it, again using the 3M 468MP tape. Heatup time dropped considerably and it's much more stable. Of course it also cuts cycling so saves energy, reducing load on the power supply.

    Heating up aluminum is *might* not a great idea (even if it is tin foil) due to the extreme temperatures...Aluminum fumes are linked to Altzhiemers(sp?) disease (though I cannot say where the safe vs. unsafe temperature range is since it must be okay to some temp since it is widely used in cooking). Not really sure how much of an issue it is but just tossing it out there as something to consider.

    @Questor: Heating aluminum does not produce fumes. Just cooking things in aluminum is a problem. (Note that the whole heated block of most hotends is made of aluminum).

    Perhaps fumes was a bad choice of words, but heating aluminum increases aluminum oxidation, which is bad. Of course the thickness of the aluminum and the temperature also come into play, but there is no doubt that there is an increased oxidizing effect of heating aluminum, and bad side effects such as Metal Fume Fever (amoung many others): https://en.m.wikipedia.org/wiki/Metal_fume_fever

  • After having seen this answer to this question, How can I insulate my thermistor?, I ordered these, from eBay, 5PCS 3mm Thick 3D Printer Heating Block Cotton Hotend Nozzle Heat Insulation EW, for around £0.40

    enter image description here

    Blurb from the item's description

    • Thickness: 3mm

    • Dimension : 75mm*21*3mm +/-0.2mm

    • The heat insulation cotton is used for 3D printer nozzle keeping warm;

    • The heating insulation cotton is made from heat-resistant ceramic fiber;

    • The product sizes can be customized according to customer needs;

    • The benefit for keeping the key parts of the 3D printer heating aluminum block warm;

    • Is making the internal temperature flat, saving power,and energy;

    • This High temperature resistant cotton can work for a long time in high temperature of 900 degree.

    Other images:

    enter image description hereenter image description hereenter image description here

    Granted, these look suspiciously like the strips in Ryan's answer, but use cotton, en lieu of ceramic tape.

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Content dated before 7/24/2021 11:53 AM