Nice to read you could confirm our findings: thermal paste makes things somewhat better and evens out any differences between left and right hotend (for some reason the right hotends seem to have received even less thermal paste than the left ones on our printers and probably others), but does not fully solve the problem.
1 Like
On my donāt was paste on both. On the right was no PTFE inside the head
Could you Use the brass volcano adapter from CNC Kitchen as the spacer above the heat break? It is 8.5mm long so you would have to cut it down to 4.5mm as per the document to fit between the copperhead and the upper adapter.
That said the volcano adapter accepts a hex driver, is there any reason why you couldnāt just leave off the upper adapter and just use the volcano adapter. You would be able to use the volcano adapter to jam-lock the copperhead in place. Guesstimating based on the pictures, it looks like the volcano adapter would sit almost flush, if not a little low, with the top of the heat sink. You might want a filament guide or something to help make sure the filament makes it in the hotend. For 7USD it might be worth a shot for those who donāt have the time/tools to machine their own spacer.
Somebody let me know if Iām missing something obvious, otherwise I will try it myself and report back.
Hereās a link to the volcano adapter: Original CNC Kitchen Volcano Adapter Version 2 ā CNCKitchen
Edit: just realized an obvious thing, the upper adapter guides/constrains the filament as it leaves the extruder gear, so just using the uncut volcano adapter wonāt work.
First the thing you noticed, and second: the thread of the upper adapter engages with the adjustment wheel on the right hotend.
1 Like
Well,
The DX for the artisan and the 2.0 definitely donāt utilize the same heat sinkā¦ thereās no threads in it for you to accomplish your modification. I also overtorqued the nozzleā¦ twisted right off. I barely put any force on it. Those bond techs are no joke.
You torqued off a V6 nozzle? Or did you mean the heat break? The latter I would understand (hence the warning in the presentation), but the nozzles are really stable. I never damaged one of thoseā¦
1 Like
Snapped the nozzle right off. It was their bi-metal variantā¦ apparently (after reading further into it), theyāre notorious for thisā¦ they want you to buy a plastic ratchet from them and print a toolā¦
Do you know what the heat block is? I need to find a suitable replacement.
The J1 uses an E3D V6 style heater block. If you are buying genuine E3D, the plated copper block is a lot nicer than the stock aluminum.
1 Like
Yes, it is a standard V6 block. I bought some plated copper blocks on Aliexpress - the ones from Trianglelab are good and much cheaper than the ones from E3D.
1 Like
Thanks guys. Ordered. Got a new Bondtech nozzle coming too. 
I kind of like the modular ness of the newer hardware. At least you can use stock parts now.
Iām excited to try those BiMetal nozzles.
If you have a STEP file I would appreciate getting it.
Assembly.step (5.0 MB)
Nozzle position.step (10.6 KB)
I have some spare PA-CF from Bambu Lab. Do you think this might be acceptable for the printed spacer, perhaps it might need to be replaced every 100 print hours are something?
For a little more detail the Bambu PA-CF has the following material properties
Vicat Softening Temperature: 210C
Heat Deflection Temperature: 160C (ISO 75 1.8MPA)
Tensile Strength: 96 MPa (X-Y ISO 520), 50 MPa (Z ISO520)
Polymaker CoPA 6/6-6
Vicat Softening Temperature: 180C
Heat Deflection Temperature: 69.8C (ISO 75 1.8 MPa)
Tensile Strength: 66.2 MPa (X-Y ISO 520), 43.3 MPa (Z ISO520)
Well, I shared my calculation here, but feel free to try it.
Personally, I would not trust that however. Polyamide aka Nylon is prone to long term pressure creep, therefore you can mostly forget the nice-looking datasheet values in this case. The added carbon fibres reduce the problem, but they do not eliminate it, and we are talking about some hundreths of a millimeter here at best between full pretension and zero. Better stay in sight of the printer when using it in this case 
Iām still waiting for my J1 to arrive, so it may be some time before I can test.
Thank you for posting the calculation for us and all your work. So I can understand is the 100kg pressure the force applied by the extruder in the Z axis?
At the location of the spacer the filament is still solid correct? If so, is the force of the extruder radiating outwards in the x/y plane to the same extent as the force in the linear Z direction downwards through the heat break into the hotend? So long as there isnāt a clog I am thinking the forces in the X-Y plane must be much lower because the filament is still solid and canāt expand sideways until it is molten?
I have tied to research the material properties of PTFE tubing that is commonly in hotends in a similar location. The Tensile strength of the PTFE tubing I can find is 20-35 MPa and Hardness Shore D 65 vs around 95 for PA6. Carbon infused nylon would still be subject to a lot more wear and the filament drags past compared to PTFE, but looks to have similar or stronger āhardnessā and ātensile strengthā as PTFE tubing.
As soon as I get my printer I can try test and report back on the condition of the break in real world conditions. Thanks againā¦ Rob
Now I get your misunderstanding. The requirement has absolutely nothing to do with filament forces or with the force of the nozzle (apart from the fact that it shall not come loose).
The only reason why this is necessary should become obvious if you take a look at the design of the āassemblyā slide in the presentation above and the corresponding text: in opposite to the original J1 heat break, an Mk8 heat break does not have a flange or something else that resembles a āscrew headā. It only consists of a threaded area. Therefore and unless you are able to cut a threaded hole for a grub screw into the heat sink, it needs to be held in place by something pressing against its top surface, thereby locking it in place. This task is done by the top screw (the one with the fine thread): After screwing in the heat break, the top screw (that was loosened before) is tightened again. By doing so, it presses onto the spacer which then presses onto the heat break, thereby creating a screw pretension and locking it in place. This is what prevents unscrewing of the heat break, in the exact same fashion as the axial force created by tightening of the nozzle prevents unscrewing of the heat break in the heat block.
@Mechanikus, may its possible to use this heatbreakes too ? May for people that donāt can build the distance piece
