Nickel Heat Transfer

I got a Princeton Tec Genesis a few years ago. It seemed like a really nice light at the time -- 2 x CR123A, forward clicky, reasonable beam (no 'before' beam shots; I've already taken it apart). Now it seems very dim and limited. It is big enough for a 17670 so I think I'd like to turn it into something like a Milky Room Sweeper, but that takes better thermal management than the PTG head offers.

The original emitter has an odd, bulbous dome which I have not seen on any photos of emitters here. All I remember from the ads when I bought it was 3W. It had a little white grease between the LED and a black plastic disk that threaded into the head. This provided a stable mount, but couldn't do much with heat created by a larger emitter.

I thought it should get at least an SSC P4, but this will require more than a silly plastic disk as a heat sink. If I glue an MCPCB star directly in this head it would be very difficult to change emitters again. I tried a nickel coin and found it fits very well. If I sand one side flat then glue it in place with some Arctic Silver epoxy, would that transfer heat well enough to let a P4 or MC-E (or your suggestion) on a star run at high current intermittently?

I'm not even sure this is the right sub-forum since I'm asking about the termal characteristics of nickel (and Arctic Silver), but the M/M/M sub-forum seems to discuss tooling more than heat transfer characteristics. I look forward to reading your thoughts.

Thanks,
Steve

when the heat is already spread out far enough BY another item, like the star, the speed of transfer over the large area is not as critial. the departure of the heat off the metal is.

whereas when your trying to get the first initial heat away from the Small emitter item and spread out to a larger area , the speed of the transfer there is more important.
and the most important is getting the heat out off the metal into the air . if your heat sinc is no bigger than, or translates to no more air or anything than the star itself, then what have you gained? just a big lunk of metal getting hot.

when limited to very small spaces in a vertical arrangement and you cant get more actual to air AREA for to extract the heat, i have done a weird trick that "fins" the 2 items.

|o| <-- like this but flater
you have a star which IS a heat sinc good for the first 130-160ma or so, then you use a copper transfer that is very small in the MIDDLE to transfer 1/2 the heat to the next hunk of metal. Then air still can pass in the psudo fins that are there, then both items , not just the one transfer heat to the air (which is still stuck in the case).
Then hot air forms between the 2 surfaces as seperated by the copper transfer, and forms a miniture chimney of convection (heat rising) .
so you have about 2 times the exposure to the air, and a bit of chimney, making the very tiny spaces you have avilable to 2 times the area, INSTEAD of the usual attaching a hunk of JUST MORE METAL, to the item.

it might sound complex, but the idea is very simple, transfer 1/2 the heat from the middle of the star, where the emitter heat is most, to the next item, then the star itself is 1/2 of the exposure to air instead of loosing the stars OWN ability to get to the air. when so limited in area , and you cant get more INCHES of air exposure.

also at any plumbing hardware store you could get copper easily enough for cheap, say like a endcap for a 1" copper water pipe, then bandsaw the top off.

other ideas for getting more SQinches of air exposure in tiny space is a "folded" heat sinc air travels vertically up through a folded over many square inches of metal.

if its just a tiny Emitter item, then you must transfer quick to a good spread first, any slower transfer there is going to have the emitter ticked off because the heat needs to leave IT.

VidPro said:

when the heat is already spread out far enough BY another item, like the star, the speed of transfer over the large area is not as critial. the departure of the heat off the metal is.

Click to expand...

Exactly. I was looking for a way to move heat from the star to the outside of the head where air can help cool it. I imagine nickel is not as good as aluminum or copper at that, but I'm not sure if the difference is worth a lot of manual shaping of metal since I don't have a lathe or mill to fabricate the ideal part (like a better head :naughty.

VidPro said:

when limited to very small spaces in a vertical arrangement and you cant get more actual to air AREA for to extract the heat, i have done a weird trick that "fins" the 2 items.

|o| <-- like this but flater
you have a star which IS a heat sinc good for the first 130-160ma or so, then you use a copper transfer that is very small in the MIDDLE to transfer 1/2 the heat to the next hunk of metal. Then air still can pass in the psudo fins that are there, then both items , not just the one transfer heat to the air (which is still stuck in the case).

Click to expand...

An interesting idea, but Princeton Tec took that possibility away from us. The head of this light is roughly a cylinder with some decoration on the outside and some rough places on the inside -- very open in the middle where your copper sandwich has worked in other lights. That is why I was asking about the nickel coin (low cost disk of exactly the right diameter to fill the gap).

VidPro said:

at any plumbing hardware store you could get copper easily enough for cheap, say like a endcap for a 1" copper water pipe, then bandsaw the top off.

Click to expand...

I hadn't thought of cutting up a pipe cap. In this case, I think a 1/2" cap might almost do since the I.D. of this head is about 22mm. Thanks for sharing some ideas. I'll have to visit my local hardware store to see what else might fit. :thanks: