diy Reviving the DIY Heatsink

[Padenormous]

So I know this has been discussed before, and that Linus has done two videos on it already. But, I feel like the attempts didn't take into account a few better options. 

 

1. 3D printed material. There are better material they could print with that could have been burned off/melted out much easier. Woodfill PLA or gluetype material generally used for support. Besides that, I'm not sure what % they used to fill the interior of their cooler, but if they make it 10% solid instead of 100% that should allow for much easier burning off.

2. Design. I think the solid block with a straight line of fins is the laziest design possible. Even if their Heatsink would have came out as designed, it still probably would have been at best the same as stock Intel coolers. Why not go for a high surface area geometry or even fractal design. Yes this would be harder to design, but this is 2017 and LTT obviously knows enough to either Matlab it up themselves or find a fanboy online who knows exactly about this type of design.

3. Aluminum instead of copper?? Why?! That amount of copper is going to cost nothing especially if you're just scrapping it out! And for god sakes, use some Borax in that melted metal before pouring it!

4. Bypass the heat spreader IHS. Why not take their CPU IHS off, weld it in some fashion to their finished heatsink, and then Thermal paste that bad boy back on directly to the silicon? Eliminate every issue and give them known improvement In thermals.

 

Believe it or not, I'm actually working to do something like this. I'm in the process of stripping about 200ft of copper coax and collecting it. That should give me ~10lbs to work with. I've used solidworks to design other objects, I own a Prusa i3 MK2 3D printer that I know how to use.

 

If anyone is at all interested in bouncing ideas around with me, I'm more than excited to talk with you. 

 

[Beowulff83]

30 minutes ago, Padenormous said:

I'm in the process of stripping about 200ft of copper coax and collecting it.

I'm assuming you have some specialty coax and not run of the mill RG-6 as this is mostly a copper clad steel core center conductor.  Just don't want you to go to all the trouble of stripping 200' to find out at the end its steel.

[mariushm]

You can just go to an online distributor of electronic components and buy the largest and tallest heatsink you can afford... then just cut holes where needed so that the heatsink would sit flat on the cpu.,.. and maybe make holes for some tall components like capacitors or inductors. Then slap a 140-200mm fan on top and you're done.

 

Here's for example (sorted by price descending because usuall bigger and heavier is more expensive and better heatsink: https://www.digikey.com/short/qc3djp

 

Welding the IHS to heatsink is a bad idea, really bad idea.

 

 

[Padenormous]

Good call on that copper cable...stuff it totally magnetic. I guess I'll just have to find another scrap source. Thanks for saving me that headache! 

I know I can buy a heatsink but, like custom water cooling, I feel like the point of this is to be able to look inside my PC case and enjoy my handy work. The fun would be designing, casting, and mounting a functional entirely home made heatsink with hopefully mid-range thermals that I could move between rigs as I upgrade.

 

Why is welding the IHS to a heatsink a bad idea, a really bad idea?

[Wobblyyyy]

Funny. I actually had to create my own about a day ago because I didn't have any other options.

[Padenormous]

@Wobblyyyy sarcasm? 

Read your comment history, definitely not sarcasm!

[Padenormous]

Alright, after scrounging around my basement, I found about 3ft of 8awg copper wire and about 10 feet of copper pipe. I think I'm set on some free copper now. Next step is to work on the design of the heatsink. I'm considering something like a fractal pyramid.

[Wobblyyyy]

8 hours ago, Padenormous said:

Alright, after scrounging around my basement, I found about 3ft of 8awg copper wire and about 10 feet of copper pipe. I think I'm set on some free copper now. Next step is to work on the design of the heatsink. I'm considering something like a fractal pyramid.

Wowwwwww.. That looks really complex. Way more so than what I thought a DIY heat sink would look like

[Padenormous]

Honestly, having thought about it more that probably won't work right. The issue comes with the top half of the Pyramid, it's not going to have enough surface area contact with the bottom half to get a sufficient amount of heat drawn to it. Still contemplating. Maybe a cube variation? 

 

Also, I wouldn't mind adding some heat pipes, but I imagine that's going to add too much complexity. 

[Padenormous]

Been watching some videos on heatsink design. Apparently if I can get the heatsink black, that will improve heat absorption and radiation as well. Apparently as width of the heatsink increases, heat disapation increased by a factor of 2. Hight only increases it by a factor of 1.4.

[bennyg1]

12 minutes ago, Padenormous said:

Been watching some videos on heatsink design. Apparently if I can get the heatsink black, that will improve heat absorption and radiation as well. Apparently as width of the heatsink increases, heat disapation increased by a factor of 2. Hight only increases it by a factor of 1.4.

Black rad thing is a myth. Heatsinks work by convection, not radiation (and certainly not absorption!)

 

Convective heat transfer is maximised by surface area and airflow. Lots of thin fins and lots of air blown across them. It's not lazy... it's the most efficient design possible

[Padenormous]

@bennyg1 I think you're right in that the black heatsink isn't going to do as much for me as adding fins/surface area, but black body radiation definitely isn't a myth. I agree that lots of thin fins and air blown across is effective, but their are thousands of other designs they could have gone for other than a simple block/fin setup and it would have been more interesting and potentially more efficient.

I think I'll forgo the anodizing of the copper for a number of reasons, number one being that apparently you can't anodize pure copper. I do think I'll aim for a wider base base though.

[lsstefan]

On 9/4/2017 at 4:18 AM, Padenormous said:

snip

 

What about using the base design like this 

 

but with longer and curved and different size fins, like 

 

I know super bad example the grass thing but I can't put into words the image in my head... Also, I don't think small fins like grass are good, stay with big fins, but the grass is the curved example.

 

Ow and if you're going for long wire type fins, make them spread across the whole case.... Probably look like crap I know, but all I can think about now is a flowery type heatsink that rises from the CPU into the sky to cool it... =)))

[Padenormous]

@lsstefan I actually had a thought of making the copper look like a fire. Sounds lame, but I'm wondering if the shape of a flame has some thermal properties that maximize heat dissipation? I've done no research on this and I could be way off, but just brainstorming. 

[lsstefan]

2 hours ago, Padenormous said:

@lsstefan I actually had a thought of making the copper look like a fire. Sounds lame, but I'm wondering if the shape of a flame has some thermal properties that maximize heat dissipation? I've done no research on this and I could be way off, but just brainstorming. 

Yes that fire is very much what I wanted to say

Well the walls do seem wide, maybe you can add more layers to the inside like a flower's petals, this way you get way more fins and it still looks good.

[Padenormous]

So I was just thinking, it's going to be near impossible for me to 3d print at the level I'm going to need to make a proper mold for copper casting. Even if I did, that cast is going to need to be ON POINT and that may too prove impossible. What if Linus and the team designed their heatsink, sent it off to Shapeways, and they could actually print it in aluminum for them! I just checked it out, and it's no more expensive than half the stuff they already waste money.

 

I think it's worth a shot!

[mariushm]

I think the ideal is thin fins close together with a lot of ... ribs, striations, whatever the term is ... all those increase the total surface of each fin

 

I'm thinking of something like what you see below, second or fourth model from the right:

 

 

So picture that second from the right but very thin metal and not so wide , and each of those vertical fins like that. If they're too wide, they block the air from the fan above when forced cooling is used.

It's easy to do one for power supply like in picture using extrusion, you make one long bar and cut chunks out of long bars as needed. but you can't use same extrusion process for thin cooler fins, too expensive and hard. Also, the cooler would be have better performance but much noisier, all those extensions will mess with the air flow through fins.

 

There's some relation between thickness of each fin and height of fins and how close together they are - too thick and then above some height you no longer gain much

If you use fins shaped like in the picture above too close together will block the airflow through the fins.

Keep in mind that there's convection and forced cooling, some of those heatsinks are optimized for convection , to let colder air at the bottom of heatsink warm up and rise and move heat out letting cold air go in the heatsink, ad others are optimized for airflow - you shove a fan above or sideways which pushes air through the fins (but those tall fins and close together won't be good for natural convection)

Heatsinks like those flames won't do because if you put a fan above, a pocket of air will basically be trapped in the center and then act as thermal insulator.