EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: djacobow on October 03, 2017, 04:20:54 am
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So, I never seem to have the heatsink I want on hand, and they can be quite pricey on digikey for blobs of metal. So I've taken to making heatsinks at home from strips of aluminum stock. The local Home Despot has flat bar, 90 degree, "U" and box aluminum for a few bucks for four feet and I can get a lot of heatsinks from that and a little sawing and drilling. One thing that I like doing is forming a single sink that can attach to several components simultaneously, regardless of their arrangement on my board.
Obviously, this will never fly for situations where you need finned and more complex heatsinks, but I'm curious, is there some reason this is a fundamentally bad idea?
I don't think I've seen many others doing it. For example, a quick YT search shows people doing some weird stuff to make heatsinks but I didn't see anybody starting from bar stock.
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U or C shaped stock, sure..Ive seen it done before.
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I found they don't work well for bigger stuff because you want max. surface area. Hence the fins on commercial heatsinks.
Flatbar and angle extrusions, although big just don't get rid of heat, they have low surface area.
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If you're looking for medium to large heatsinks, check out heatsinkUSA.com. They have a wide range of heatsink profiles from about 1" on up.
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The price of the heatsink is in the cutting, sawing and milling.
Stick to standard sizes that the major brands stock.
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china has been dumping aluminium for years, US heatsink manufacturers won a trade suit on it so tariffs now. If the shipping costs are not too high, Ali has tons of heatsinks cheaper than the raw metal.
The hardest part is threading the heatink for screws, I'm terrible using a tap and die.
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Buy (for cheap) or scavenge an old crt tv and you'll get tons of 'em, both the small and big ones. I got ~10 threaded heatsinks (with the matching screws, of course) of different shapes and sizes from a small, old sony tv thrown out into the curbside. ;)
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An excerpt from W1FB Design Notebook (copies available if you google). Making your own heatsinks has been done for a long time because they were historically expensive. Any old crap you had lying around did the job. I actually made them out of aluminium section recovered from when my parents' house had double glazing put in and the old windows were scrapped.
(https://i.imgur.com/zlPUeGe.jpg)
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DIY Heatsink
http://sound.whsites.net/articles/diy-heatsink.htm (http://sound.whsites.net/articles/diy-heatsink.htm)
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You can always buy sheet aluminium or copper, then cut them into strips and braze / solder them together to some rather thermally efficient shapes.
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Multiple components on a single heatsink can be dodgy if they don't have enough flex in the leads to allow them to bend and lay flat on the heatsink surface. I probably wouldn't consider it for surface mount stuff as you'd struggle to get the components co-planar enough to all sit flat on the heatsink.
floobydust, if you're having trouble tapping heatsinks then maybe try one of these tap guides? Ably demonstrated by your most skookum countryman AvE:
https://www.youtube.com/watch?v=LzKZOIt1okA (https://www.youtube.com/watch?v=LzKZOIt1okA)
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A good source of DIY heatsinks is to get architectural aluminium extrusions, often used for commercial office cubicles, walls and such, as these often have a flat section and some form of angle and ribbed area on them. Generally the offcuts are perfect for use as a DIY heatsink, and I did make quite a few out of these, using the parts tossed by shopfitters as source. Even made a monster for a power supply, which was capable of handling over 200W of dissipation, from 6 2N3773 transistors, without issue. I was more limited by the power source, the wiring was not capable of doing over 20A without dropping 10V from the 28V source. Emitter ballast resistors were simply 30cm of PTFE coated 22AWG wire wrap wire, all equal length, and while they did get warm they were otherwise perfect, with one being used as the current shunt sense resistor.
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How about melting aluminum into bricks and CNC them in any desirable shape?
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With how cheap heatsinks are on ebay, I just try to have a few copper/aluminum options with me, and then I save heatsinks from boards that get trashed or whatnot. Maybe you have to drill a hole or two for good mounting, but a lot of times a sticky thermal pad or thermal adhesive will do the job just fine.
Aluminum channel is good too, but you should even be able to find extruded aluminum stock for heatsinks (usually sold as heatsinks for high power LEDs) and just cut to fit.
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china has been dumping aluminium for years, US heatsink manufacturers won a trade suit on it so tariffs now. If the shipping costs are not too high, Ali has tons of heatsinks cheaper than the raw metal.
The hardest part is threading the heatink for screws, I'm terrible using a tap and die.
Forming taps work excellent in soft aluminium and as a bonus there is no swarf. The downside is that you need the right size drill bits.
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DIY Heatsink
http://sound.whsites.net/articles/diy-heatsink.htm (http://sound.whsites.net/articles/diy-heatsink.htm)
Beat me to it.
Buy (for cheap) or scavenge an old crt tv and you'll get tons of 'em, both the small and big ones. I got ~10 threaded heatsinks (with the matching screws, of course) of different shapes and sizes from a small, old sony tv thrown out into the curbside. ;)
I sometimes scavenge heatsinks out of obsolete PCs, that people leave abandoned on the sidewalk. The motherboards usually have small heatsinks for the chipset and processor (can be repurposed for an rpi, for example). The PC power supplies have beefier heatsinks for power devices.
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DIY Heatsink
http://sound.whsites.net/articles/diy-heatsink.htm (http://sound.whsites.net/articles/diy-heatsink.htm)
Beat me to it.
Buy (for cheap) or scavenge an old crt tv and you'll get tons of 'em, both the small and big ones. I got ~10 threaded heatsinks (with the matching screws, of course) of different shapes and sizes from a small, old sony tv thrown out into the curbside. ;)
I sometimes scavenge heatsinks out of obsolete PCs, that people leave abandoned on the sidewalk. The motherboards usually have small heatsinks for the chipset and processor (can be repurposed for an rpi, for example). The PC power supplies have beefier heatsinks for power devices.
I occasionally harvest them from old PCs before we scrap them, some of the CPU heatsinks are incredible, to buy something not intended for a PC CPU but with equivalent thermal performance can be ridiculously expensive.
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Indeed. The best ones for bang for buck are the Pentium III Xeon heatsinks. They have nice grooves so you can cut them up if you want smaller ones:
(https://i.imgur.com/lsNy6xE.jpg)