I want to resurface this aluminum heatsink I bought off e$bay. It has some epoxy/ceramic-like conductive material on top. I can't scrape it off and heating has no effect.
What would I use on my CNC to resurface this heatsink? The dimensions are: 9 1/8 x 8 3/8 x 1 3/8 The surface on the heatsink has to be smooth so that there is an optimal transfer of heat.
I'd consider paying someone else to do it too. Preferably in Raleigh, NC. However, the heatsink cost me ~ $10 off e$bay and my local machine shop wants $75 to resurface it. I can't see myself paying 7.5x the original price...
Its probably hard anodizing. If your going to use it as a heat sink, why remove the coating? If you just want it flat, get a sheet of 220 grit wet/dry sandpaper and put it on a flat surface, the move the heat sink around on the paper until its flat and smooth.
If it is anodized you have to get under the anodizing on the first cut, or it will instantly dull your cutter.
You are likely going to have to polish the heat sink after machining to get the optimal heat transfer. Do it on a surface plate.
You typically want to do this with any heat sink, even brand new out of the box.
I've built a lot of computers, trust me
The more flat and even the surface, the more uniform the heat transmission between the chip and the heatsink is. In effect fully utilizing your heat sink to the best of its design, and ultimately keeping your electronics cooler.
It is not so much getting a mirror finish as it is ensuring the surface is flat, which is why I mentioned a surface plate. You can polish any surface to a mirror finish, curved or not curved. What I am talking about is known as lapping.
Someone once told me that we should make our usernames as descriptive of ourselves as possible. I cannot think of a better name for the likes of you.
And yes, SirDenisNayland, you are correct. I will be sure to polish after I am through (polishing I actually have the tools for!). I too have built my fair share of computers, but I admit, I have never gone the extra mile to re-polish heatsinks after they have arrived from the factory. I normally apply Artic Silver 5 and be done with it.
The hard anodizing is also fairly non-conductive, electrically. You really don't need a mirror finish, just flat.