Originally Posted by jeff-o
The Luxeon datasheets recommend at LEAST 1 square inch per watt, which would be at least 5 square inches for a 5W Luxeon. This is assuming the Luxeon is properly connected to the heatsink with thermal paste or whatever you decide to use. However, for more reliable operation I'd recommend more than 5 square inches, just to be safe.
Okay, how about this
tailpiece? Then I used thermal cement to attach three turns of 3/16" copper tubing to the Luxeon's metal substrate. The tubing then interfaces to the tailpiece to dump the heat. I got a lens designed for a Luxeon, plus a version of a buck puck. I took pictures before I assembled the light; I'll post them soon. Oh, to seal up the end I have a PVC cap that fitted. Drill a hole for the electrical wires, put some silicone sealant on it, and the light is done!