Cash as a heatsink

[pedalinbob]

http://www.usmint.gov/about_the_mint/fun_facts/index.cfm?flash=yes&action=fun_facts2

"The composition was pure copper from 1793 to 1837.
From 1837 to 1857, the cent was made of bronze (95 percent copper, and five percent tin and zinc).
From 1857, the cent was 88 percent copper and 12 percent nickel, giving the coin a whitish appearance.
The cent was again bronze (95 percent copper, and five percent tin and zinc) from 1864 to 1962.
(Note: In 1943, the coin's composition was changed to zinc-coated steel. This change was only for the year 1943 and was due to the critical use of copper for the war effort. However, a limited number of copper pennies were minted that year. You can read more about the rare, collectible 1943 copper penny in "What's So Special about the 1943 Copper Penny.")
In 1962, the cent's tin content, which was quite small, was removed. That made the metal composition of the cent 95 percent copper and 5 percent zinc.
The alloy remained 95 percent copper and 5 percent zinc until 1982, when the composition was changed to 97.5 percent zinc and 2.5 percent copper (copper-plated zinc). Cents of both compositions appeared in that year."

so it loks like 1962-1981 are good years for making heatsinks--because they are easy to find, and still 95% copper.

ok, i had nothing better to do today...

Bob

 

[gadget_lover]

I read the title to this thread and thought first of the cost of making heat-sinks, then the cost of buying them. When I got to your post it all made sense.

Instead of a penny, how about quarters and dimes? Aren't they copper clad with silver? I've used a dime in an AA battery sized light, and it seems to have worked well.

Daniel

P.S. The cost of a heat sink..... $1.50 for aluminium stock. $350 for lathe, $250 for accessories. I think I need to build a 9 more. The first one cost $601.50 but it's only $60 per heat sink if I make 10. /ubbthreads/images/graemlins/smile.gif

 

[McGizmo]

Gadget_Lover,

I think you want a Mercury dime.

My first Luxeon light consisted of a penny soldered into a copper plumbing fitting; great thermal path!

 

[paulr]

Zinc is really a lot different than copper. Drilling a hole in a nickel or dime is a clean operation, but drilling a zinc penny makes a real mess.

 

[stockwiz]

Seems like a cheap way to make a heatsink. I collect coins and have plenty of silver.

 

[pedalinbob]

[ QUOTE ]
gadget_lover said:
I read the title to this thread and thought first of the cost of making heat-sinks, then the cost of buying them. When I got to your post it all made sense.

Instead of a penny, how about quarters and dimes? Aren't they copper clad with silver? I've used a dime in an AA battery sized light, and it seems to have worked well.

Daniel

P.S. The cost of a heat sink..... $1.50 for aluminium stock. $350 for lathe, $250 for accessories. I think I need to build a 9 more. The first one cost $601.50 but it's only $60 per heat sink if I make 10. /ubbthreads/images/graemlins/smile.gif

[/ QUOTE ]

thanks for the info--i did not realize that the silver stuff had copper in it.
we need to buy some heatsinks from you to dininish your overal costs.

$600 for a heatsink!!! LOL!!!

it must be wonderful to have your own lathe.

Bob

 

[chalo]

[ QUOTE ]
gadget_lover said:
Instead of a penny, how about quarters and dimes? Aren't they copper clad with silver?

[/ QUOTE ]

The cladding is nickel-copper alloy-- not very good at heat transfer. Better to use a pre-'82 penny at 95% copper, or better yet a pre-'65 quarter or dime, which are 90% silver/10% copper.

It's not hard to find a coin dealer who will sell 99.9% silver coins of no collectible value for their metal value plus a dollar or so. A quarter to a half ounce silver coin would make a fine heatsink if filed flat under the LED and well connected to the flashlight body.

Chalo Colina

 

[PEU]

just curious, how much for a pound of such coins?

 

[Doug S]

[ QUOTE ]
PEU said:
just curious, how much for a pound of such coins?

[/ QUOTE ]
Friday's closing price for $1000 face value of US silver coins [containing about 715 troy oz of silver] was $4359 USD.

 

[Doug S]

Cash as a heatsink? Why not? Flashlights are certainly a cashsink.

 

[NewBie]

Is that like sunken cash?

 

[gadget_lover]

[ QUOTE ]
Doug S said:
[ QUOTE ]
PEU said:
just curious, how much for a pound of such coins?

[/ QUOTE ]
Friday's closing price for $1000 face value of US silver coins [containing about 715 troy oz of silver] was $4359 USD.

[/ QUOTE ]

It took a while but with a troy oz = 31.103 grams and a pound = 451 grams, I see that as around 88 dollars per US pound, or 5.52 dollars per US ounce.

Hmmmmm. a silver light????

Daniel

 

[tvodrd]

If you can't afford a silver flashlight, how about at least some silver battery contacts? /ubbthreads/images/graemlins/grin.gif

Larry

 

[Xrunner]

[ QUOTE ]
Doug S said:
Cash as a heatsink? Why not? Flashlights are certainly a cashsink.

[/ QUOTE ]

ROTFL, very true. /ubbthreads/images/graemlins/hahaha.gif

-Mike

 

[idleprocess]

[ QUOTE ]
gadget_lover said:
P.S. The cost of a heat sink..... $1.50 for aluminium stock. $350 for lathe, $250 for accessories. I think I need to build a 9 more. The first one cost $601.50 but it's only $60 per heat sink if I make 10. /ubbthreads/images/graemlins/smile.gif

[/ QUOTE ]If you're going to amortize your capital equipment over so few units, go ahead! Every other project only costs you labor+materials from now out!

 

[kenny]

I do silversmithing and lapidary etc. I was thinking of making a silver flashlight. There would be two ways -- 1) buy a plastic one and the put it in plaster and burn it out and then pour the molten silver in (vacuuming the flask) or 2) carving a wax and then putting that in plaster and burning it out. I teach the wax carving class, so that part would be doable, but doing some rough calculations, it would be around $20-$25 buck worth of silver -- not bad I guess. One problem is getting threads in the wax, but I guess you could tap and die them in. Also, you could rig it to accept some semi precious stone etc. on the outside -- real medevil looking AND cooler even than knurling! Anyway, I thinking...

 

[Unicorn]

That would be the coolest light I'd probably ever see in my life. Keep thinking about it until it wears at you and the only way to stop obsessing about it is to actually make it. /ubbthreads/images/graemlins/grin.gif

 

[cheesehead]

silver light bottom of the page

 

[Justintoxicated]

Defacing Money Is ILLEGAL, now I'm off to sand down a few pennies and lay some quarters on the railroad tracks to make heatsinks,

Peace!

 

[gadget_lover]

Once it's sanded down, it's no longer money, is it? /ubbthreads/images/graemlins/smile.gif

Daniel