I'm not sure how far I'll get before all the additional manufacturing complexity nudges me over the edge to essentially say "Well, it was a good run, but that #SlimeSaver [gd0105] isn't solving itself and still has the optimistic appeal of potential performance." but I've currently modelled a potential heatblock candidate that is about 3.3 cm3.

I may have to extend the length of the press-fit tubes, as they're currently 5mm and all examples I've found look like they're >7mm:

Considering that a V6 hotend is installed, the tube does look to be around 7 - 8mm here in this SV08 hotend.

At 7mm, the heatblock is 3.5 cm3.

Series of events

I first designed the heatblock how I've always designed ones in the past, but it seemed to use more material than I'd like:

This was 5.6 cm3; too much when I'm targeting 3.5 cm3 which is the amount for a standard volcano hotend.

I then had the idea to use the Shell command to create the minimum-material-needed heatblock. Only the "rounded" type works anyway. The straight-edged shell would've used more material for little benefit:

The above is 2.6 cm3, proving that a solution within target could exist.

Next, I proceeded to delete a few faces, add the dowel holder, and fillet things:

I think it looks nice, like an engine, so I kept the top non-symmetric like this.

The dowel orientation is such because it was easier to make a nicer looking design.

I tried the first orientation, but it only saved a negligible amount of material, looked less sleek and I eventually came to the conclusion that there was nowhere else for the heater to go but where the leak path would spill into.

For the heater, an ideal solution might have been the clip Mellow came up with in their CHP hotend:

I don't think the clip alone is available, so I've modelled in geometry for a more traditional cartridge heater/thermistor, attached with nothing but boron nitride paste. They're not enclosed in part to save on material and to allow easy access of water to remove the cartridges if they need replacing.

The cartridges are then insulated with 3mm wool that was used back in a time before silicone socks. Here, I'm using it as a shield against material wisps.

It's designed to take a 15mm cartridge, but I'm going to test with a 20mm 70W one.

Closing statements

D3D, in their listing for a hotend they sell, does seem to confirm my worries about thermal expansion on this press-fit solution. I'm not sure exactly how thermally conductive this heatblock actually needs to be considering all the twists and turns inside of it, so printing in stainless-steel is still looking the most ideal.

If anything, I might just take a page out of XYZDims and see if PCBWay or JLC can print 0.5mm thin tubes which I drill on the inside. I might have to ream too, but a rougher surface finish would both help with heat transfer of the filament and would actually turn the drawback of those pre-bimetal, chinesium all-metal heartbreaks into a feature by promoting "clogging" when the input is off. It might also save money both in material savings of the printed part but in thin-wall tubing too.

[M] Created heatblock using outer-shell

Series of events

Closing statements

Discussions

[M] Created heatblock using outer-shell

Series of events

Closing statements

[R] Press fit tolerances

[M] Stainless print in place heatbreaks?

Discussions

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