Edit: Just ran a 12 hour PC print with zero hiccups.
The background is, I have a qidi plus4 that goes to 370c on the nozzle. The really good thermal paste goes to 350c max. For cheap stuff, it boils off the liquid part of the paste around 300c(leaves behind what looks like white smoke residue around that area). The factory qidi paste is 6W/m-K and only rated to 240c lol
I was replacing the paste every 10 or so prints, trying to keep up with it because I only print high temp stuff with this printer.
Started thinking about the new graphite pads that have come out in the last decade or so. Ones like thethermal grizzly kryosheet. Bought the kryosheet and then found that its not rated for extremely high temps. Went back to looking and found one that goes to 400c, seems indestructible and has a 35(W/m-K) heat transfer performance. This is probably 2-3 times as good as the paste that comes on printers.
These pads arent like old school, soft, thick thermal pads. These are paper thin, completely dry, are hard but can rip and are reusable.
Heats up to 270c in 45 seconds now. Ill let you know if I see any downsides, but so far I dont.
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Air isnât a very good conductor of heat. So when thereâs a gap between whatâs generating the heat and where the heat is supposed to go, filling the gap with something that conducts heat better than air improves the heat transfer.
Thermal paste does this. It isnât as good a conductor of heat as direct surface-to-surface contact, but itâs quite a bit better than air.
Thermal Interface Material (TIM) pads are better for some use cases, compared to paste. But generally, theyâre used where the two mating surfaces are flat, and where paste is impractical for some reason.
Like, when the top of a component has to dissipate heat to an external cover - if you use paste, you have to deal with a mess when you remove/replace the cover. If you use TIM, you just have to make sure the slip of material is back in place before driving the screws.
Iâm surprised the pad material is working so well. If thereâs enough clearance to get the heater in with a wrap of this stuff around it, I wouldnât have expected it to be tight enough in the heat block for good uniform contact.
There are high temperature thermal pastes. A bit of overkill, but Boron Nitride paste, for instance, is good to 850ÂșC (in air. Itâs good to 1800ÂșC in vacuum). It has a slightly lower 31.4 W/mK. But if the TIM has any air gaps, the paste would probably do a better job of moving heat to the heat block faster.
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This is what people miss. Theres a difference between normal thermal pads and graphite pads. I only know about them because they became popular when i was gettjng deep in to watercooled pc builds.
" A silicone thermal pad is made of silicone material and offers good flexibility and a wider range of thicknesses, while a graphite thermal pad is primarily made of graphite, providing significantly higher thermal conductivity and is typically thinner, making it ideal for applications requiring superior heat transfer in a compact space; both are used to dissipate heat in electronic devices, but graphite is generally preferred for high-performance applications where maximum heat transfer is needed.
Key differences:
Graphite thermal pads have significantly higher thermal conductivity than silicone pads, meaning they transfer heat more effectively.
Silicone pads are more flexible and can conform to uneven surfaces better than graphite pads.
Graphite pads are usually much thinner than silicone pads, allowing for more compact designs.
Silicone pads are often used in general electronics where moderate heat dissipation is required, while graphite pads are preferred for high-power components like CPUs and GPUs."
If you look closely, the graphite pad has micro dimples that squish slightly to help get an even mating surface.
Meh. TIM is TIM. I use this kind of stuff all the time in products Iâve designed in my real world job. Theyâre all designed to be âsquishedâ a little during final assembly of whatever theyâre being used in.
In fact, what I said above was not completely correct - you donât reuse a TIM pad because itâs been compressed from its original use and it wonât retain good contact with its mated surfaces when reused.
Youâre wrapping a cylinder with a slice of this stuff, and then inserting it all in to a circular bore. If itâs not basically line-to-line tolerance, if it fits at all loosely, contact is going to be lost in some areas.
Not saying that the TIM pad wonât work, only that it might not be working as well as youâd like to think itâs working. It canât if there are air gaps between the TIM and either surface itâs supposed to be in contact with, and Iâm not sure I see how there wonât be air gaps.
You say âheats up to 270c in 45 seconds nowâ. How long did your printer take to heat that high before you made your change?
My printhead has always heated up very quickly. If I get a chance, Iâll see how long it takes to get to 270ÂșC for comparison. I bet itâs not much different in its stock paste-based configuration.
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The plus 4 uses the same type of flat heater against a flat surface that the x1c uses. Not a cylinder. Assumed you would have googled that first. Also, they are not all equal. Theres 2 completely different types of pads. Made from completely different things and have completely different characteristics. You wouldnât use a thermal pad on a cpu or gpu core itself. You would use a graphite sheet on the core itself.
Not sure how long it took to heat up before, but I know that while watching the screen readout, the numbers are climbing much faster⊠The factory paste was 1/6 as conductive
Now that you know this, should help with your real world job. If you were using the two as if they were equal. My guess is that you probably use old school silicone pads.
Do you have a plus 4?
Just started another tray of PC parts.
If the mating surfaces are flat, then I agree a pad will work.
Yeah, I havenât taken the time to look at the heater and was making a bad assumption about how itâs designed⊠my bad. 
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All good. Something like this is bound to attract skepticism . You should see some of the facebook responses.
Hereâs my 5 cents worth in regards to pads and transfer pasteâŠ
I my old job I had to deal a lot with repairs of high power electronics but also dedicated heating and cooling solutions for then.
We had a wide variety of thermal paste, grease, pads and even ceramic sheets available.
Basically a dedicated product for every possible case.
Hereâs the funny thing:
Despite literally entire shelves full of different thermal stuff our go to solution was old, basic and still superior when there was no need for an electrical insulation.
An oil based pasted with silver and copper particles as the main ingredient.
Brush onto one side, wait until the surface starts to look dull to indicate the oil is drying up and mount together, preferably with good final pressure to squeeze out any excess and flatten the metal articles.
I also used the stuff to repair demisting strips on rear windows in my old cars.
Tape off, brush on, let dry and rub shiny with a plastic spoon or such.
We also use graphite, graphene and carbon based pads, mainly for things requiring military grade standards.
The benefits of them are dead obviousâŠ
Superior heat transfer compared to standard pads, literally no degradation issues from aging and being super thin.
These pads also have a few minor downsides thoughâŠ
Like the issue of only having ONE attempt to get it rightâŠ
Meaning that in the rare case that something moves these pads can fail badly.
Not a big deal for a print head but a big concern if it is something like a processor or big and vital mosfet.
Considering we only have this spring clamp to secure the heating pad I am not 100% if these pads are reliable long term option.
But then again, there isnât really any forces involved unless a print would go terribly wrong.
If you are after a high temp solution that can be even thinner:
For some applications where electrical conductivity is not an issue I use fusible alloys.
Some melt already below the 100 degree Celsius mark but their main benefit is their very high boiling point.
Had no need to mod my E3D with it but when the time for a new heating pad comes it would go like this >
Clean the hotend properly, connect the pad to a lab power supply to get it just above the melting point of the alloy.
Rub the alloy over the pad to create a more or less even layer.
Alloys with some Gallium in it work best as they will âwetâ almost any surface but they canât be used with aluminium or copper parts as the gallium degrades them.
Wipe thin and flat using a blade or such and let it cool down.
Mount to the hotened with some wooden peg and heat to just above the melting temp - wait for the alloy to melt and push out, wipe off any excess.
Add the spring and sock and Bobâs your aunty.
One major drawback:
Test the metal surfaces first if you use a gallium based alloy!
If it wets the metal and leaves a discolouration that wonât wipe off it means the gallium fused with the metal.
Aluminium is a no go here, steel, especially stainless and chrome surfaces should be fine though - still test first.
Donât really see a need for it in a printer for normal filaments but for mainly high temp filaments and a high temp printerâŠ
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@user_3026326371 Which E3D did you have?
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The Obxidian and very happy with it.
Just too bad that the P1S canât keep up with the speed and PID control these hotends allow for.
Am printing PLA and PETG basically at max speed when the parts are simple enough and the max flow rate is set to around 40âŠ
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I like this Idea. I have liquid metal but what alloy would I use to fuse them? The heater is kinda built into the hotend on the plus 4 anyway, so im not losing anything. If the heater fails, gotta toss the block every time anyway.
I thought about ising the liquid metal but assumed it would drip out on fast movements. Plus I doubt the hotends are nickel coated
Donât confuse fusing with fusible 
A low melting alloy like Rose metal, Fieldâs metal or Woodâs metal all have melting points below the boiling point of water.
Liquid metal is no good here as you have a bloody hard time applying it and keeping it in place.
Need something ghat melts at 400c-500c
