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Information on Lapping.

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Dec 23, 2000
I've looked around the Overclockers.com site, and cannot find any info on lapping just the heatsink. I found a site with info on it, but no pics. I have a pretty basic idea how to do this, but I would like to read somthing with pictures added to it to be sure. I went and bought 1200, 800, 600, 330, and 260 grit sand paper. So I'm read to do it. I'm just an information hoard. So please, I'd like to try this today. I just need a little more info before goiing into battle.
you will be fine, what you want to do is use progressively finer grits until you get a mirror like finish on the bottom of your cpu, that is it!
This is a reply I posted to a similar question, no pictures, sorry. I hope it helps;

There's a bit more to lapping than just "smoothing" it up. What you are also trying to achieve is a perfectly flat interface between the mating surfaces of the heat sink and the CPU core. If you were to take a straight edge to the surface of the heat sink you would find that, in many cases it's not straight and true. To remedy this you should sand the base, In addition I would recommend that you place the sandpaper on a pane of glass, tape it down if necessary, pay attention that you don't tilt the heat sink, resulting in a heat sink with an angled bottom causing uneven pressure when attached to the motherboard. Follow the above procedures and use progressively finer paper, finishing with a polishing compound if needed to achieve a mirror-like finish. Use no waxes or other foreign material other than a quality thermal transfer paste between the heat sink and the CPU.
You should see a noticeable decrease in your temperatures after performing this procedure.

Good Luck!
To know when the bottom of the heatsink is flat, you can draw an X with a Sharpie b4 lapping. When the X has disappeared, the bottom is flat (providing u lapped it on a clean pane of glass, of course)
whats the deal with the glass that i keep hearing about-is glass always a totally flat surface?? just wondering cause i lapped it and onthe the edges were getting sanded, but i sanded till it sanded the center also. ??Hence my signature???
smooth glass is close enough to flat that it's a perfect "work bench".

I've been using my kitchen counter for a while....think I have to quit soon tho.......my G'friend pitches a fit over it!
The edges are getting sanded more, because your tipping the heatsink slightly as you sand. What I do is tape the sandpaper to a thick piece of plate glass. I have a drafting light table, so this is easy for me. I use automotive wet/dry paper. A little water helps flush the metal particles away. Aluminum has a tendency to clog up sandpaper pretty quickly. I usually start out with 400 grit, don't go too low or it'll scratch up the heatsink. That 260 is probably too coarse and maybe shouldn't be used. Next, carefully move the heatsink in a circular motion or better yet a figure 8 motion on the sandpaper. Use light pressure and be patient.Lapping is time consuming if done right. If you only go up to 1200, that's not bad, much better than not lapping it at all. I like going up to 1500 grit myself, but if you're careful, 1200 will be really smooth too. Tada, you've got your sink lapped. Use a good thermal paste and good luck!