Little Quick Passive Case Design...

[LjSpike]

I got a bit bored, and didn't feel like doing much work today on the case I'm actually going to build, so designed to just quickly begin designing a passive case...

I'll extend it to a greater depth at some other time, but it looks quite nice this heatsink pattern I've done, I'm wondering, how effective would it actually be at being a heatsink?

 

[h_tylr]

Looks neat, although, the centre hole on the 'T' shaped 'fin' seems a little strange, as little to no air would be able to escape from it, so it would act as a poorly preforming heat-pipe.. There are no dimensions, but I would presume a heat-sink of such calibre would preform well with higher TDP parts compared to something like the streacom db4's thin sides! Also, you might know this already, but increasing the amount of approximated line segments in Sketchup makes curves look a whole lot better! It'd be nice to see if this goes anywhere!

 

[LjSpike]

Looks neat, although, the centre hole on the 'T' shaped 'fin' seems a little strange, as little to no air would be able to escape from it, so it would act as a poorly preforming heat-pipe.. There are no dimensions, but I would presume a heat-sink of such calibre would preform well with higher TDP parts compared to something like the streacom db4's thin sides! Also, you might know this already, but increasing the amount of approximated line segments in Sketchup makes curves look a whole lot better! It'd be nice to see if this goes anywhere!

With SketchUp I don't mind it looking slightly basic, as to get SketchUp files to look spectacular takes more effort then it's worth at points.

That is a fair point with the hole inside the T-shape, No air would actually get into there... I might look at potential ways to rework it, I might either do it as 2 "r" shaped pieces, or perhaps I could feed down some slim extensions to heat pipes through there so some of the heat pipes actually force fluid through the heatsink itself...
The dimensions weren't really my concern yet, just coming up with a concept, I'll have to look into some heatsink part dimesions. How thick do you think the metal for such a heatsink should aim to be? (As too thin would result in structural weaknesses and too thick wouldn't distribute heat as well...

 

[h_tylr]

How thick do you think the metal for such a heatsink should aim to be? (As too thin would result in structural weaknesses and too thick wouldn't distribute heat as well...

I don't typically work with custom extruded aluminum, but my train of thought would be somewhere along 1 to 1.5mm minimum of an aluminum magnesium alloy, which would offer strength, and the ability to get a nice finish. As for which specific alloy and its thermal properties, thats beyond me really. Another thing to think about is the curved corners, as curved extrusions are something I've never come across, and although they sound plausible, they may not be a thing, or may be very expensive. Milling it could be another option, but again, it'd be costly...

 

[LjSpike]

I don't typically work with custom extruded aluminum, but my train of thought would be somewhere along 1 to 1.5mm minimum of an aluminum magnesium alloy, which would offer strength, and the ability to get a nice finish. As for which specific alloy and its thermal properties, thats beyond me really. Another thing to think about is the curved corners, as curved extrusions are something I've never come across, and although they sound plausible, they may not be a thing, or may be very expensive. Milling it could be another option, but again, it'd be costly...

I could handle the curves by making the fins separate to the main case, sliding then onto the case then brazing or welding them in place perhaps? I agree, extrusion of curved parts could be tricky, milling could be an option as you say, perhaps milling it in a few chunks and attaching those together might be another alternative...

 

[Sicaris]

A job for 3D printed metal perhaps?

 

[LjSpike]

A job for 3D printed metal perhaps?

Perhaps, although that'd be a rather costly manufacturing method wouldn't it?

 

[h_tylr]

I could handle the curves by making the fins separate to the main case, sliding then onto the case then brazing or welding them in place perhaps? I agree, extrusion of curved parts could be tricky, milling could be an option as you say, perhaps milling it in a few chunks and attaching those together might be another alternative...

Perhaps, although that'd be a rather costly manufacturing method wouldn't it?

You'd almost be better having just a quater curved section in the corner, to bolt the heatsink panels on to, it'd cut costs and complications massively... Its hard to explain, but once I'm back home, I can do a quick mock up if you want.
As for 3D printing it, the costs would indeed be high, and the quality of finish and structural integrity would most likely suffer..

 

[LjSpike]

You'd almost be better having just a quater curved section in the corner, to bolt the heatsink panels on to, it'd cut costs and complications massively... Its hard to explain, but once I'm back home, I can do a quick mock up if you want.
As for 3D printing it, the costs would indeed be high, and the quality of finish and structural integrity would most likely suffer..

Yeah, I think I understand but a quick mock-up might help...

 

[iFreilicht]

I really like the idea, and the extrusion looks quite cool, apart from the hole inside the T section that @h_tylr mentioned. That should just be a solid piece. The heat dissipation can be found through simulation, I won't judge that yet.

The issue I see with this is the bending. The extrusion base together with the T section forms a very rigid cross-section, so if you wanted to manufacture this, the extrusion would have to be heated up during bending. This is why other passive cases always have their extrusion parallel to potential bend lines, not perpendicular. That way you can also manufacture the whole shell in one extrusion and don't need many additional steps.

 

[LjSpike]

I really like the idea, and the extrusion looks quite cool, apart from the hole inside the T section that @h_tylr mentioned. That should just be a solid piece. The heat dissipation can be found through simulation, I won't judge that yet.

The issue I see with this is the bending. The extrusion base together with the T section forms a very rigid cross-section, so if you wanted to manufacture this, the extrusion would have to be heated up during bending. This is why other passive cases always have their extrusion parallel to potential bend lines, not perpendicular. That way you can also manufacture the whole shell in one extrusion and don't need many additional steps.

Mhm, my thought of a workaround for manufacture would be to mill the pieces of the heat sink seperately to the panel of the case and then to weld/braze/join them together as you could just slide them on. Would this effect its ability to conduct heat though? I mean, it's possible that air gaps could then form...

 

[iFreilicht]

Mhm, my thought of a workaround for manufacture would be to mill the pieces of the heat sink seperately to the panel of the case and then to weld/braze/join them together as you could just slide them on.

This would work if the edges/bent parts looked different, but at least with the T section you currently have, milling isn't possible. For performance it's probably better to only have the top and bottom act as the heatsinks, make the sides look different, and put the whole thing upright.

The thing with passive cooling is that you need to generate airflow somehow, and that is done by making the gaps between the cooling fins act like chimneys. With the design you have right now, the air inside the gaps, especially under the T-section, can't go anywhere and if it could, there'd be no way for fresh air to fill the void.

Would this effect its ability to conduct heat though? I mean, it's possible that air gaps could then form...

Welding would be difficult because you have to join all the edges together separately and chamfer them as well, so it would take a lot of time. You could join the pieces with special kinds of glue, maybe. I don't know whether brazing would work reliably, but it's certainly the best option if doable.

Really, as cool as the design looks, I don't think it's feasible and there's a good reason why nothing like this has been done before.

 

[LjSpike]

This would work if the edges/bent parts looked different, but at least with the T section you currently have, milling isn't possible. For performance it's probably better to only have the top and bottom act as the heatsinks, make the sides look different, and put the whole thing upright.

The thing with passive cooling is that you need to generate airflow somehow, and that is done by making the gaps between the cooling fins act like chimneys. With the design you have right now, the air inside the gaps, especially under the T-section, can't go anywhere and if it could, there'd be no way for fresh air to fill the void.



Welding would be difficult because you have to join all the edges together separately and chamfer them as well, so it would take a lot of time. You could join the pieces with special kinds of glue, maybe. I don't know whether brazing would work reliably, but it's certainly the best option if doable.

Really, as cool as the design looks, I don't think it's feasible and there's a good reason why nothing like this has been done before.

Mhm k. Thanks for the input.