I have to admit I fail to see how you might want to use these.
It might be good to take the 3D model of the original J1 hotend I posted on MyMinifactory and try to add that heat break to explain what you are planning.
I mean to drill the cooling part out from above or may it fits in like it is. I donât know, this was just a idea.
Well, as I said: take the hotend model, create a 3D model of the heat break you suggest and try to combine them in the way you think of.
Thanks Mechanikus for the detailed explanation, I understand a lot better now.
Rookie questions I know, but:
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what if you just used threadloc or super glue on the MK8 heatbreak to bond it to the upper assembly at the correct height and then used PTFE tube for the spacer? Itâs a one time fix and wonât be coming out at a later date, but how often do you need to replace upper assemblies and heatbreaks anyway? (perhaps only glue/threadloc the upper 1/2 threads so heat paste can be used on the lower half nearest the bottom heat break to aid thermal conducitivity?)
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substitute your grub screw concept with a nut at the bottom of the heatbreak superglued/threadlocâed on the and possibly soldered between the nut and the lower threads nearest the heatbreak. then the nut can be used to friction fit the heatbreak to the upper assembly and a PTFE tube inserted was the spacer.
In either cases the heatbreak could be set at a lower point than i3svenâs design in order to put the bottom of the nozzle 3.5mm lower to match the original specifications?
You could use super glue or threadlock indeed, but that would be tricky with the additional thermal paste the connection requires.
Apart from that, I like having the chance to replace the heat break in case of a crash - the thin walled connection will probably be bent out of place in such a case. If you donât care about that, feel free to try it 
You might want to keep in mind that the lowest area of the upper portion of the heatbreak is the most critical area to be cooled. If you use a nut for that, this area is not in good contact with the heat sink which will result in significantly decreased cooling. We did not want to replace one problem with another, so we discarded that idea.
The same applies if you do not push in the heat sink fully: the air flowing through the lower area of the heat sink will be blocked by the housing of the hotend, resulting in reduced cooling there. Apart from that, you may get issues with the hotend plug not being inserted fully into its socket inside the hotend (some guy here in the forum even seems to have damaged his hotend connector because of that, at least this is what I read from his post - this may be the reason why Snapmaker explicitly notes to ensure the lower end of the heat sink is not below the housing in their hotend manual) and with the screws that have a very small contact surface even when the hotend is fully inserted.
And now for something completely differentâŠ
I was disassembling one of my old Monoprice Mini printers for a different project and noticed the old heatbreak used a M6 thread. This is the opposite of a âfull metalâ hotend. The M6 threaded stainless steel piece is a hollow tube and the PTFE runs all of the way down into the heat block and rests on the top of the nozzle. Max temp is limited to 250C due to the PTFE.
Out of curiousity, I swapped one of my hotends over to this antiquated heatbreak and loaded up some dual color silk PLA. I was able to print continuously for multiple hours without a single clog. The GCode I was using was unchanged from previous tests where I would reliable get clogs within minutes of starting.
While it worked great, I certainly would not recommend this change as a solution to the clogging issues. However, it is an interesting data point. Everything upstream of my hotend is completely stock. Stock spool holder. Stock PTFE feed tube. Stock filament runout sensor. Stock extruder. Stock cooling fans. The only things that were not stock were this heatbreak and the nozzle. From my testing, it appears the sole problem is the design of the stock heatbreak.
Yes, that fits exactly to our finding! The J1 heatbreak is the problem! 
With that PTFE lined hotend you circumvent any issues with heat transfer and early melting of the filament simply by using the PTFE liner. This is the reason why such hotends (such as the E3D Lite6) are still sold and frequently used by the way - they are easy to use and very forgiving. The downside however is a reduced melting speed and a reduced max temperature.
So I am loving all of these findings you guys have done to correct the issues with the printer.
I havenât tried to take this machine apart - my only exposure is building the Ender 3v2 and replacing that hotend due to a massive clog.
Iâm a little at a loss about what parts I need to purchase to correct the issues this printer has without bricking it due to the closed nature of the firmware and leveling and whatnot, plus I do not have access to tools to make or modify parts - are there parts I can purchase I can âslot inâ to correct what you have found?
Iâm in the USA and would gladly love to fix this printer so I can use it reliably.
On the top of this tread u can find this pdf documentation. https://forum.snapmaker.com/t/findings-and-solution-for-the-snapmaker-j1-clogging-problem
I use for the insert to lock the heat break some brass M6 worm screw and cut them to 4.5mm
Lets see whatâs happen. Hope this will work
Nozzles I use creality spider speed nozzle or micro Swiss Brass Plated Nozzles
The heat break are slice engineering copper head MK8
You also need thermal grease. On my stock hotends was nothing and on the right extruder was the PTFE insert missed too. I use kyronaut high performance thermal Grease
Thanks
The heatbreak and the nozzle is noted in the documentation the JohnDoe mentioned, these are stock parts. I use Microswiss V6 nozzles, but the nozzles JohnDoe mentioned work as well - the basic requirement for them is that they need a longer thread than an MK8 nozzle.
The only thing you must make yourself is the spacer (or get made by a workshop - anyone capable of basic metal working should be able to do this easily - and if he has a lathe in his workshop, this should be a piece of cake)
the other option as JohnDoe has suggested would be to cut off an M6 hex grub screw with a hex of at least 4.5mm depth - the hexagon in there is usually large enough to let the filament through. The difficulty with these is that you usually do not know which parts are actually tightenend against each other since you have three threaded metal pieces in a row then, this something you would normally avoid. Thus, it is advisable to follow this mounting procedure in this case:
- follow the procedure in the documentation until you screw the heat break into the heat sink.
- when this is done, screw in your âspacerâ and use it to tighten the heat break. I do not know if you will be able to reach the full required torque stated by Copperhead with it, but try to get as close as you can get without deforming it.
- Then insert the top screw and tighten it as defined in the document. Make sure it is not mounted against the heat sink (again, see above for details)
May be I try to sand the screws down on the outside, they are Brass, so it will go easy I think. Than I have spacers too.
I will try that may be
I thought your fan change solved the problem? Does it not?
It does but not for all kind of materials, so I upgrade them too. Meanwhile I hope the upgrade parts from Snapmaker come quickly
Ok, what fan do you use? There are no more modifications than just changing the fan?
Parts from snapmaker or Bondtech?
Bondtech parts and fan for heatsink cooling is a Sunon I think.
Also I use kyronaut thermal grease.
For Standart filaments it works but u also need other Nozzles.
But if u want print flexible or other special material better do the complete fix.
Just as a side note: the only area where thermal paste is a must is between heatbreak and heat sink. There, you do not need the fancy stuff and can use a standard PC thermal paste instead. I used the Arctic Cooling MX4 since I had a leftover from that, but anything that is good for a PC processor works there as well.
If you want to use thermal paste in the heat block, you need something better though. Copperhead explicitly suggests using Boron Nitride paste there.
Damn it, itâs so much effortâŠ
Didnât find a more powerful fan and already added the themal paste, but this is so annoying.
I just saw the instruction, but is there a way only with bought parts, without crafting space holders on our own? Why doing that much hassle with the spacer. In my opinion a simple, fitting tube is doing the job.
Well, if you find a well fitting tube, I guess quite some people will be very happy to read about that. The part needs to
- withstand the continuous pressure from the required screw pretension to keep the heat break at its place. This excludes any common plastic parts since these creep under load a lot earlier than metal does.
- be just a tiny bit smaller on the outside than the inner diameter of the heat sink thread is (in my case that one has 4.99âŠ5.00mm, so a 5mm pipe which usually has a nominal diameter of 5.0±0.02âŠ0.05mm just does not fit), so that it can be inserted but still gets centered by the thread
- be small enough on the inside to guide the filament when it is pushed by the extruder even if it is flexible (you definitely donât want TPU to bend or curl there). Snapmaker chose a rather generous 2.3mm for the top screw, so I kept that value. Making it larger will probably cause a reduced print quality for flexible filaments.
- have chamfers or rounded edges to allow the filament to be slided back and forward without scratching chips off and to prevent a filament tip to get stuck in the transition even if the three parts (top screw, distance piece and heatbreak are not 100% axially aligned.
- needs properly parallel surfaces on its ends to allow transfer of the pretension force
- should have some small (!) chamfers on the outer edges to allow easy insertion and removal without causing trouble when assembled by reducing the already small contact surface towards the heat break and therefore causing material creep by overload. Copperhead has the technical drawings on their website, so you may check the minimum surface area yourself if you like - you just need the calculate the effect of the geometric tolerances they use
Feel free to search for an alternative - any working suggestions will be highly appreciated