Heatsink Adhesive Ways

I realize heatsinks are nothing new but I was trying to figure out a way to better secure them to the inside the flashlight. With the diameter of the heatsink fitting so snug inside the flashlight I noticed that the adhesive was just oozing out as I pushed the heatsink in, leaving minimal if any adhesive at all. This proved insecure especially in mods where the batteries and spring put constant upward pressure against the heatsink.



I decided to cut some grooves or ways in the base of the heatsink allowing more of the adhesive to stay put and provide a better bond. I then tried it in one of my mods and found that it worked better than I had anticipated. There was hardly any adhesive overspill as I pushed the heasink in and once dry it wouldn't budge.

Any other ideas or suggestions? /ubbthreads/images/graemlins/popcorn.gif

How about an "interference fit" ? make the sink diameter a tiny bit larger than it should be, then put it in the freezer overnight. this will cause it to shrink a bit, pop it in your flashlight, then when it starts to warm up, it will expand back to its original size.

I use an interference fit whenever possible along with a mechanical locking means if possible.The more direct(and larger) the contact the better the heat transfer. Heating one and cooling the other works like a charm.
Chris

the point of a heatsink inside a light is to distribute heat from the heatsink to the body. the best way to do this, is maximum contact area between the two.

what the reliefs are doing is keeping the thermal goo in between the "fins" where it isn't doing much good.
i think it would likely be better without the reliefs, and have maximum body-contact area.

and really, even though vast majority of the stuff is pushed out, there is still a thin film in between the heatsink and the body, doing what it does...filling in the microscopic pores between the heatsink and the body. on it's own, thermal goo isn't a good conductor at all.

i think you may find that the reliefs adversly effect heatsinking /ubbthreads/images/graemlins/frown.gif

maybe a better way would be to put a layer of regular epoxy on the top of the heatsink?

if you're still set on the groove idea, maybe one groove would be enough?


very nice looking heatsink btw! what lathe do you do you have?
i've found that a small platform coming up from the larger platform, the diameter of the emitter really helps in centering...but of course, this isn't the case with stars /ubbthreads/images/graemlins/grin.gif

I think your heatsink rocks! Between the four ribs, there is PLENTY of contact area for direct heatsinking to the body.

I agree with your reason for doing this (to resist battery spring pressure). I rectified the same problem by scoring lines with a carbide bit around the circumference of the body just above the heatsink. Then I slathered on a bead of epoxy around the edge of the heatsink and body using the scores for the epoxy to bond to..

kakster - Great idea, I never thought of using an interference fit. I'll have to try that. /ubbthreads/images/graemlins/thumbsup.gif

Rothrandir - Thanks, I agree with you partially. I beleive it would be more important to have as much contact as possible on a smaller mod where the heatsink is smaller and therefore would heat up quicker and need somewhere to go. In this situation you would want maximum contact between the heatsink and the flashlight so that the flashlight could also absorb the heat.

I use a Micro Mark 7x14 lathe that I really like. I was originally going to purchase the Homier which is a very nice machine but the Micro Mark had a few more key features that I was looking for. When I first started modding I use to make all of my heatsinks by hand with a Dremel which was hard work and took forever. What was I thinking? /ubbthreads/images/graemlins/ohgeez.gif

Slick - Thanks for the positive words. I really like the groove technique it seems to work well, especially on those mods where the spring and batteries are putting upward pressure on the heatsink.

I guess I could always seal the heatsink in with Epoxy but that doesn't always look good. I like for my mods to look as nice as they work and the groove technique is very clean. /ubbthreads/images/graemlins/wink.gif

yup, the heatsinking is more than adaqauate /ubbthreads/images/graemlins/grin.gif
but some of you may have noticed that my middle name is overkill /ubbthreads/images/graemlins/grin.gif

the micromark is supposed to be a very nice lathe.
i have the hf 7x10. it is a decent little lathe, but it's got a very low capacity and is metric /ubbthreads/images/graemlins/frown.gif
it was only 329 though /ubbthreads/images/graemlins/grin.gif