Solid Silver Heatsinks!

[andrewwynn]

Well.. i made a trade to make a sandwich for a CNC123 for a bud on cpf... he sent me a VIP driver to assemble with a TWOJ emitter.. but i needed to make some heatsinks for his and other CNC123 lights..

Well i've made one already using some PCB material but the copper on those is mighty thing and what i really wanted was some solid copper i could cut using the same method... he said he happened so have some from his days as a jeweler... so i teased him that.. well silver is actually more conductive (thermally and electrically) than copper... so he fired back.. 'well i have some sterling silver laying around too'..

The title of the post ruins the punch line of course.. but the summary is.. after some tedium and a LOT of oil.. i was able to use my wood plug-cutter to cut some solid sterling silver heat sinks.. i'll post some pictures soon as i can they are very cool. They look like a dime before it is struck.. but a little smaller diameter.. in any event.. my guess is they are the only two in the world.. who'd be nuts enough to use actual silver to make their luxeon heatsink, huh?

the post-tedium and lot of oil.. was that the first try was abysmal .... the cutter just kept grabbing the material and moving it around.. it was like a fancy silver spyrograph.

I tried again with copper.. and it wasn't much easier but being softer metal it did work... but that was last night..

today i decided to try clamping the material harder.. and starting slower.. and using constant oil bath.. and sure enough it worked.. in a matter of 5 minutes i had a perfect little slug of silver.. in-fact in 10 minutes i had two silver slugs and one more copper one... this time the silver actually cut easier than the copper.

Well.. back to the saltmine.. i'll post pics when i get a chance.

ok: pictures:


click on the picture for a couple more.

the center disc is a copper PCB.. the far two discs are copper heat sinks..

when taking the time, the plug cutter works fabulously well for cutting perfect circles.. it creates a bit of flashing on the back side of the hole as it cuts that needs to be sanded off but quick few sec. with a dremel and it's a perfect circle.

-awr

 

[wasBlinded]

Silver isn't so expensive, really. Those little slugs don't weigh very much.

Sounds like the perfect thing for the typical obsessive-compulsive CPFer.

 

[Rothrandir]

silver is something i've always wanted to use in lights!

i keep meaning to look into prices for bars of silver, but was always afraid to... /ubbthreads/images/graemlins/icon15.gif

and, err...where are the pictures? /ubbthreads/images/graemlins/twakfl.gif

 

[PhotonFanatic]

Well, a finished Groovy! only weighs 2.2 ounces, so with silver at $6.60 an ounce, it wouldn't be terribly expensive, except for one thing--fabricated silver sells for much more than spot silver. And the availability of, say, 1" bar stock is probably zilch.

One would have to make one's own bar stock, not an insurmountable task, but not trivial either.

Still the eye appeal and the feel in the hand of sterling silver tempts me, too.

 

[Lynx_Arc]

Or just get an old silver coin. I got about 10 silver dimes I took out of the ground with my metal detector... mercury dimes.

 

[mahoney]

A tip for next time:
If you are having trouble cutting thin metal with a plug cutter or hole saw, try clamping the metal between two thin pieces of wood or plywood and drill through the stack.

 

[MrMom]

Hmmmmmm

Valentined day is just around the corner...thinking...

Hey honey, look what I got you for Valentines day!

 

[andrewwynn]

i have to measure a dime.. it's actually kinda close to this size.. but you'd have to do a loooot of filing/sanding/grinding to shape it down... the key to this was (once figuring out to lubricate and clamp enough).. that it makes a perfect circle just the right size (i did have to buy the bit.. about $15).. so.. so far the sinks cost like $3 each.. could be worse.. the 100+ heat sinks i made for nano cost about the same each when you factor in the $25 rod and the $275 tool to cut it into discs.

-awr

 

[StoneDog]

I made a solid "copper" heat sink from a $.20 coupling that I bought from home depot. I split, flattened and cut the sink by hand and then carefully filed it to make sure it was as round as I could get it. It took a loooong time and the end result still wasn't perfect.

A plug cutter would've made the job MUCH easier. Why didn't I think of that!? /ubbthreads/images/graemlins/banghead.gif

So, awr how much will you be selling these copper and silver heatsinks for? /ubbthreads/images/graemlins/smile.gif

Jon

 

[OddOne]

You can get silver discs from United Nuclear for $2 per for a 1" disc. No idea how thick or how much weight, but I'm sure they'll tell you in response to an E-mailed query. I've used silver from other sources as heat spreaders in processor-cooling applications, and it's definitely better than copper at thermal transfer.

oO

 

[StoneDog]

Can silver be soldered as easily as copper?

They also have pure copper "sticks". Cool site oO! /ubbthreads/images/graemlins/smile.gif

Jon

 

[paulr]

Go to a coin shop and ask to buy some silver rounds. They are privately minted coins about the size of silver dollars and usually weigh one Troy ounce (31(?) grams, a little more than a regular ounce). You'll pay a dollar or so higher than the current spot silver price/oz ($6.60? Ouch!). You can often also get silver bars at coin shops.

 

[DaMeatMan]

I've recently used an old penny for the same purpose. The reason why i used an old one like pre 70's, is because i know for certain that at some point in time they stopped using so much copper in Canadian pennies and now adays seem to use a less efficient alloy for disapating heat, however it is tougher and most likely less expensive to produce. Anyhow all i did was allot filing to get it down to a perfect smooth slug which is identical to the pics in the first post of this thread. I'll post a couple pics too in a bit.

 

[dimwatt]

I have been thinking of that for a while. I do sterling jewelery so when I found out that Luxes needed heat sinks, the heat absorption/dissipation of sterling or even nickle silver makes it a perfect choice.

Andrew, you might want to anneal the silver before trying to cut it. Annealing softens the metal and makes it a whole lot more workable.

dimwatt

 

[dimwatt]

Another thought. For small lights one could use an old silver dime. Mercury dimes are cheap. I have a pot of them I found while metal detecting. No key dates though.:-(

dimwatt

 

[Leeoniya]

i'm thinking of getting a 6"x2" strip of 10ga. sterling silver...yes, that's correct

6"x2"
0.102" thickness.
92.5% silver
7.5% copper

$64.77 without shipping.

not cheap, but not too bad. this stuff is thick. and you can get about twelve 7/8" heatsinks i dont think anyone is good enough to extract 12 1" heatsinks.

here's the source:
http://www.thunderbirdsupply.com/product.asp?id=YQ

i have a freind jeweler, i'm gonna see if he can make me that magic Cusil alloy of 72% silver 28% copper.

 

[StoneDog]

[ QUOTE ]
dimwatt said:
I have been thinking of that for a while. I do sterling jewelery so when I found out that Luxes needed heat sinks, the heat absorption/dissipation of sterling or even nickle silver makes it a perfect choice.

Andrew, you might want to anneal the silver before trying to cut it. Annealing softens the metal and makes it a whole lot more workable.

dimwatt

[/ QUOTE ]

Nickel Silver is typically an allow of copper, zinc and nickel. It doesn't actually contain silver. Even so, does the addition of nickel or zinc make it a better heatsink material than pure copper?

Jon

 

[greg_in_canada]

This page (link) shows the thermal conductivity
of nickel silver as 28 W/mK

Look at the bottom part of this page (link) for silver (at 418 W/mK), copper (at 388)
and other metals.

So I think sticking with common heatsink materials
(copper, aluminum or silver) is best.

Greg

 

[StoneDog]

Wow, Pure Al seems to be much better than the 6061 alloys and 6061 is far superior to Nickel Silver. Copper seems to be quite a bit better than Al and silver is close to 10% better than Copper!

Thanks for the link Greg! (and sorry if I hijacked)

Jon

 

[dimwatt]

OK, I screwed up. I hadn't done any tests or research on nickle silver but thought the metals combined woulkd work well. WOW! what an eye opener on the properties!