Thermal contact across machined threads?

[MilchstrabeStern]

I'll be fabricating a 100% custom host for a 445nm M140 diode out of a 1.5" diameter, 12" long aluminum cylinder. I may end up using the full length, and most likely the full diameter (I feel like the heftyness of such a laser will carry with it the implication that it's a dangerous device). Such a large amount of aluminum also affords a great heat sinking opportunity for the diode.

In my current design, there are 1 or 2 threaded connections between the parts that hold the diode and the outer shell of the host (the bulk of the aluminum). How much actual metal on metal contact is there in a typical threaded connection? I'm trying to determine if the contact area is enough to adequately transfer heat from the diode to the outer shell.

 

[Cyparagon]

I've taken thermographs of various flashlights in operation. The case is usually composed of many different parts that thread together as you may know, and I see virtually no insulation between the parts. This one for example has the cylinder for the battery, the shroud for the pill, the crown that holds the window in place, and the tail cap.

Threads are fine. Just be sure it's not loose when you assemble it.

 

[MilchstrabeStern]

I would very much like your FLIR camera.

Okay! Well, I'll give it a shot. I'm not too worried to begin with as I won't be driving it higher than 1.8W and the diode itself will be pressed into a good chunk of aluminum itself.

 

[Zathras]

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[Cyparagon]

That is not necessary. Thermal transfer is fine, as you can see. That just makes things messy, and there's no way you can properly apply it. Besides, thermal grease has tiny particles of ceramic which will put a lot of wear on the threads.