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rightey, my lights are hot on the inside and cold on the outside (it's melted the insulation on the wires!)
So, to improve the heat flow to the outside I recon I need 2 things.........
Some electricaly non-conducting but thermaly conducting paste to put under the LED (cree Q5) to transfer heat to the heatsink better.
And some thermaly and electricaly conducting paste to take heat from the heatsink to the outer caseing (there's only a +ve wire to the driver, the earth comes back through the caseing).
Where can I get such magical concoctions??
I'd use this for both applications http://uk.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=554311
Then drill & tap a small bolt into the heatsink to get the electrical connection.
hmmm, the heatsink screws into the body so I'm guessing the paste will be displaced as it tightens (but still take heat away though the bits with no metal/metal contact?
Could wrap some thin copper wire into the threads before screwing them together maybe?
Is the back of the cree star not insulated from the contacts? On the ones I have, it can be pressed right up against the heatsink with no worries about insulation. I know some boards may be different though. If it is, I would stick some thermal paste under, but make it as tight a fit as possible - thermal conducting paste isn't going to be as good a conductor of heat as direct contact is it?
Assuming the heat is getting to the heatsink (or you work that one out) Can you just make some holes in the casing so that the heatsink is exposed directly to the outside? That way you'd be actually using it as a heat-sink, rather than just somewhere to store up a bit of heat before chucking it out through the casing.
Joe
No, its a basterdised version of the deal extream equivalent to the tesco torch. So the heatsink is just a big aluminium (possibly a copper core) cylinder about 12mm long and 18mm diameter, threaded to screw into the torch body. But over time it unscrwes slightly and loses the thermal path to the outside world.
That and the outside is partialy covered with rubber to help with the bar/helmet mounts, so I need to make up for that.
<<thermal conducting paste isn't going to be as good a conductor of heat as direct contact is it?>>
correct, but paste is designed to fill in the small gaps between surfaces so as to exclude all the small air pockets which are a good insulator, that is why you should only use the thinnest of paste layers.
works in the same way as thread lock and retainer fluid does for fastners i.e. filling the gaps bwteen the mating surfaces but in the fastner case the gap filling stops things coming apart whereas thermal paste fill the gaps to exclude air and improve heat transfer.