How does a nozzle change work, OEM site seems to just sell the entire hot end?


Thinking of buying a J1s and am trying to understand how one changes the nozzle size. On the web site, all I see are entire hot ends for sale which seems odd - are you expected to change the entire hot end to get a different nozzle dia change? Is there some reason why just changing the nozzle won’t work?

Materials like carbon fibre are abrasive, not sure I want a machine that to replace the nozzle means a whole hot end.

It would be great if someone could explain this. e.g. what do others do, what is the nozzle thread size, if the OEM doesn’t sell nozzles, what are the options?


The hot-ends all use standard MK8 nozzles you can get on Amazon or wherever.

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With lots more reading since posting, I think I understand the situation with hot ends and the new one piece hot end.

Interesting this clogging problem and what is causing it. I had a terrible time initially with my Prusa mk3s (detailed here: The poor experience with my Prusa 3d Printer - Metallum) which had to do with Prusa deviating from the open source ID’s in the heat break. Fixed that and the problem went away. I know its a different printer, I guess the point is these problems can be tough to track down and the cause can be (at least for me) hard to pin down.

On the heat transfer business as a cause of clogging, I’m challenged to see how a threaded fit is the issue. Heat transfer is a function of thermal conductivity of the materials and area (cross section) of contact. Because of the geometry of threads, you potentially have as much or more contact between the parts.

So … in getting heat from the heater to the material, imo thread vs interference matters not very much. What does matter is the thermal conductivity of the materials. Here copper is 10x as conductive as steel and would make a huge difference; e.g. copper block I made shown in link above.

Late to the thread but the issue arises due to Snapmaker using way too little thermal compound on the original design. Almost all who reported jams had little to no thermal compound on the heatsink side.

Look at this diagram, you can see a very liberal application of thermal compound is basically required for proper operation. Now look at the image below.

This is from my post covering the process of modifying a old style hotend to a full metal configuration. The top heatbreak is from a freshly disassembled hotend and you can see the amount of thermal paste would not be enough to fill the gaps fully, especially near the critical region right where the heatbreak ends and the heatsink begins.

And this is actually one of the better ones, some only got a slight midge of thermal compound on it, and its those that are most prone to jamming.

It is changing nozzle sizes typically requires replacing the entire hot end assembly. This ensures compatibility and ease of maintenance. You have to abrasive materials like carbon fiber, this approach helps maintain printer performance. If OEM nozzles aren’t available, third-party options with compatible thread sizes can be considered.