Diamond Hotend thermal insulation sheet - alternatives

I recently purchased a Diamond Hotend clone from China, and am putting together all the pieces for a working tricolour setup.

The original official kit includes three layers of glass-fiber thermal insulation sheet, laser-cut from fire blanket. This of course wasn't included with the Chinese clone.

While I've bought a cheap fire blanket to cut-up myself, I'm wondering whether this is really the best way to go about insulating the hotend from the coldend parts - glass fibers are pretty nasty, and the glass fiber sheets are not hemmed at all - leaving the fibres loose and fraying over time.

Brainstorming other solutions, my wife came up with the idea of using a piece (or more than one piece stacked together) of silicone baking sheet (cheap, from Daiso, and bright orange to boot). I believe I can laser cut this from the DXF file, otherwise could just use scissors to get it to the right shape. The baking sheet (and silicone in general) is rated to 230C, so this should be fine for ABS but perhaps not for anything higher temp.

I can't find anybody else who has discussed using silicone as the insulator instead of the fire blanket - does anybody have any thoughts on this as an option here?

I'd be very interested to hear what other people say to this. I can tell you that I bought a genuine diamond hot end from RepRapMe and the fire blanket thermal insulation frays very easily. Basically, as you say, it's a circle cut out of a woven fabric but there is no hem around the edge (women know what this means, men do not ). Every time I touched it, another thread came off. I ended up plastering it in superglue so a better alternative needs to be found. I did see a bit of a video on the interweb of a guy who had fitted a Diamond to a Delta printer and he had some alternative form of insulation but I can't find it again.

Edited 1 time(s). Last edit at 06/08/2016 03:20AM by deckingman.

Thanks - glad to see that my suspicions about the glass fibre are well founded. I will leave the fire blanket for its originally-designed purpose, and continue exploring the silicone as an alternative.

I found that video. Someone else posted it on another thread that I had started. Mostly it's about a large Delta but about 9 and half minutes in, he mentions that he used silicone instead of the "fire blanket" and found it much better but he wasn't very specific about what sort of silcone, how thick etc. Anyway, it sounds like you are on the right lines - here is the link [www.youtube.com].

You could use a hole punch to make the hole in the middle for the heat sink or mabe just poke a hole with somethuing sharp and stretch it. The outer shape doesn't have to be anything precise so I'd have thought scissors would be fine - no need to get it lazer cut.

You can get high temperature silicone from an auto parts store, print a mold, and mold a part to fit the block. You might be able to find two-part silicone that can handle high temperatures which would be easier than squeezing stuff from a tube.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

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the_digital_dentist
You can get high temperature silicone from an auto parts store, print a mold, and mold a part to fit the block. You might be able to find two-part silicone that can handle high temperatures which would be easier than squeezing stuff from a tube.

That's an idea. Might work better than buying silicone baking sheets and cutting them up. Hmmmm........

How about gluing the fire blanket to aluminium foil. The foil would stop it from fraying, and also reflect heat downward and conduct it away.

Srek makes some awesome looking silicone insulators for his hotends, it would be worth asking what he uses.

I've gone ahead and laser cut four silicone heat shields for the assembly of my hot end, and am using three.

The silicone matting is from Daiso, cutting by Emblaser.

I did modify the original design slightly from that originally published - since there is no need for the cuts across the holes ... I will publish the tweaked files if there is more interest (and my eventual testing is successful).

Laser cutting

Finalised heat shields

Assembly

Final effector complete

Good job. Looks a lot neater than the fire blanket too. Now all we need to know is if you get any heat creep issues. I guess you could maybe do some testing without filament if you have a thermocouple reader or other device that you could measure the temperature at the heat break point. I don't have a laser cutter - are you taking orders?

Thanks, I was really pleased with the result and think it looks so much nicer than the fraying fire blanket. I have a thermocouple I could test with (ideally I'd use an infrared temp gun - i have one on my wish list), but don't have any benchmark to compare it to as I haven't even fired the thing up yet (I'm currently hamstrung by my Smoothieware controller and still trying to get it to a firmware/config that has a chance of working).

I'd be happy to cut up the rest of my wife's Daiso baking sheet for anybody else who would like to test it out (no warranties implied or liability accepted, WYSIWYG). I could probably do enough discs for another 4 hotends from what's left, and would be happy to just cover postage costs likely ~$5 from Australia. If someone can empirically compare it with the results from the fire blanket that would likely be useful for everyone. PM me if you are interested.

I could do some back to back testing but it won't be for a while. I'm building a new printer which will have a Diamond hot end. The printer is a long way off but I've already assembled the hot end which I bought as a genuine kit from RepRap.me with the 3 layers of fire blanket. I sandwiched them between 2 layers of Kapton tape in an attempt to stop them fraying but it isn't pretty and I don't think it'll last. So, before I put any filament in, I could put a thermocouple down the heat sink, and see what temperatures we get with fire blanket vs the Silicone.

Actually, I'll have the power supply in a day or so and I already have the heater cartridge so maybe I can cobble together some sort of test without having the normal PID control over the heater.

I'll PM you.

Seems to be better than my solution. I just got it and haven't got the time to update my entire build with it. My main issue is that brass is not as conductive as aluminium so it takes longer to heat up (also takes longer to cool down for the exact same reason)


Side note:
I am also working on an adapter for my build and have decided to go with a simpler design.

It is a bit cumbersome to put together, but once it is set up it gets a solid grip on the heat sinks without using cable ties. I will share the .stl after testing it.
Cheers.

Has anyone tried printing something to hold the nozzle and body as a mould and pouring in the silicone so you have a nice moulded part instead of having layers of cut cooking mat or fibre mat?

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Rlewisrlou666
Has anyone tried printing something to hold the nozzle and body as a mould and pouring in the silicone so you have a nice moulded part instead of having layers of cut cooking mat or fibre mat?

Thought about it - almost impossible to do. It's not about keeping the nozzle hot but how to keep the heat sinks cold. So, the insulation needs to stick out quite a way from the edge of the brass part but also be no more than about 2.5 mm thick and be flexible so that it'll curve to suit the angle of the heat sinks. A bit like the brim of a sombrero. If you tried to pour molten silicone around the nozzle, you'd have to do it with the heat sinks in situ or something screwed into the holes otherwise the silicone will fill the threaded holes. Same with the heater and thermistor. And you still have to form the large brim somehow. I keep coming back to a big round disc with holes for the heat sinks etc - which is what is supplied.

BTW, I did do some testing with some silicone discs that Zylantha kindly gave me. The results were not conclusive as there were a few variables. The indication was that they didn't perform quite as well as the stock "fire blanket" but this may have been due to other variables. I'd say that they performed well enough though and shouldn't be a cause for concern if anyone was thinking of making them out of silicone sheet rather than "fire blanket".

@deckingman - There must be a way to do something it is such a shame to have to use a substandard blanket on what is otherwise an amazing piece of kit.

Is there a Build Schematic available online?

I'd be more than happy to try to figure something out or a way you could shield the heatsinks without using fire blanket.

I'd love to have a play to try to work it out in person but I can't afford one at the moment.

Ryan

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Out of the box thinking is easier when you never fitted in the box to begin with.

There is a drawing of the nozzle here [iamond_Nozzle.pdf" target="_blank" rel="nofollow">reprap.org] and the wiki is here [reprap.org].

Remember, the insulation is needed to maintain a good temperature differential between the (hot) brass nozzle and the (cold) heat sinks. The "fire blanket" works well in the respect but the big problem is that it frays. I stuck Kapton tape to mine to try and prevent this. The silicone sheet version that Zylantha made should work fine too but I haven't yet tested it in the "real world" but of course, it won't fray so is superior in that respect.

Edit Try this link instead [reprap.org] - the first one doesn't work for some reaon.

Edited 3 time(s). Last edit at 10/19/2016 11:57AM by deckingman.

Its taken me some time but I've finished the nozzle I'll work on the shroud tomorrow.

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Out of the box thinking is easier when you never fitted in the box to begin with.

Heres the Hotend without a shroud.

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Out of the box thinking is easier when you never fitted in the box to begin with.

Fusion 360 Cloud Render is pretty useful when you have a little Mac Mini.

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Out of the box thinking is easier when you never fitted in the box to begin with.

why not just coat the fire blanket in silicon surely you get the best of both

Presuming that you mean silicone (a polymer) rather than silicon (an element)...

There are four types of silicone that spring to mind -

1 .Silicone spray - this is a lubricant and unhelpful
2. Silicone sealant - this is a glue-like goop that you use for sealing windows, and would be like coating the thermal blanket in glue. It would be practically impossible to get an even coat and would be a nightmare to do
3. Silicone "liquid electrical tape" - this is a paint-like goop that you paint on to electrical connections in substitution for using electrical tape. It could work, but would be VERY messy to do, and it dries with lots of bubbles in it where the solvent evaporates. It's horrible stuff to use.
4. Silicone moulding - this is a multi-part compound you usually use to make moulds (some people use it to make moulds of their hot end for insulation). This is a non-trivial thing to do, you would need to start with a mould that you can put the fire blanket into, shaped to fit correctly, with holes cut out for the throats and thermistor to go through.

The already-formed silicone mat that I suggested and ended up using is far easier to work with. While I used a laser cutter, you could also make up your own stencil / template using the PDF template for the heat shield and trace it, then use a pair of scissors to cut it out.

If you really want to use both the silicone and the fire blanket, I would suggest using alternating layers of fire blanket and silicone sheet, with the silicone sheet on the top and the bottom (i.e. silicone-blanket-silicone, or silicone-blanket-silicone-blanket-silicone). You could try to glue the layers together, or just glue the fire blanket to one piece of silicone sheet to keep it from fraying (you could try doing this with liquid electrical tape) - there is a rule that "silicone sticks to everything, but nothing sticks to silicone" - I'm not sure if you would be able to get anything to successfully glue the fire blanket onto the silicone, because it's so difficult to get anything to stick to it.

Out of all this, the combination of silicone-blanket-silicone with the three glued together with liquid electrical tape is the most interesting option.

Hi, can you share the cutting file ?

[www.thingiverse.com]

Refer the diamond_thermal_isolation files (DXF and SCAD). You should be able to use one of these as your own source and convert to PDF, GRBL etc...

Could i use cork, 2 or 3 mm?

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poliveira1978
Could i use cork, 2 or 3 mm?

Sure, if it doesn't brake apart.

Just for the record, I use demake-up cotton wool pads, but I found the fibres like to stick to the printed part. So I also cover the cotton pad with Kapton tape.

i've got the cork "coockies" and i'm going to try to assemble it with them, let's see what happens...

Just for info, the last insulation discs I got from RepRap.me weren't woven. It's the same sort of fire blanket type stuff but it doesn't fray like the originals. Also, the main purpose of these discs is to keep the cooling air (which blows downwards) away from the brass part. The mount for the 5 colour version of the Diamond has a vertical tube down the centre to keep the cooling air away from the heater cartridge. The top of the tube is close to the fan motor body and the bottom sits around the heater cartridge so air is "blown" down around this tube and exits through the heat sink fins.

I used one of my wife's panty liners,covered it in kapton tape
Made some holes in it .seems ok,only works for a month,really seems fine

Edited 1 time(s). Last edit at 09/09/2018 03:02PM by nod2.

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nod2
I used one of my wife's panty liners,covered it in kapton tape
Made some holes in it .seems ok,only works for a month,really seems fine

I really wouldn't recommend this! The fire point for cotton (assuming they are actually made of cotton) is only 210C, so it's not inconceivable that it could reach this temperature with your hotend already at least this temperature for PLA, and above it for ABS.

However there is likely to be lots of other plastic in there in the coating and seams, which could melt, and have all sorts of other nasty properties - e.g. if there's any PVC then it will let off chlorine when heated, which will then in turn rapidly rust any stainless components you have, and be a generally bad thing to have vaporised in your house (this is a common problem with laser cutting; you just don't laser cut PVC or it will destroy your laser cutter).

I started this thread about exploring alternative thermal insulation - the general warning here is to use something that was intended to be safely heated to the hotend temperatures. The original design called for fibreglass fire blanket, my suggestion was silcone pot holders, and both these are reasonably expected to hold safe to hotend temps ... but unless your wife is particularly hot, panty liners were never expected to reach 210-240C.

Stay safe!