Lapping? info needed please

Hi, I am looking for the proper way to lap my HSF I remember there used to be a post on this but was unable to find it in the search... I was wondering if anyone has a link or info on how to lap I know if has sand paper soft and water but I don't know the grit of sand paper and that.


Thanks for you help!

I think this belongs in the cooling section and not in this part of the forums... I guess you should send a PM to a mod to move it for ya.

Use wet/dry sandpaper from an autoparts store. I would start with 400 grit. Get it wet and put it on something flat (like a piece of glass). Go in a circular motion and try to keep it flat. Keep going until all the grooves and rough spots are gone. Repeat with finer grits (I went down to 1000, then 2000). At this point some use polishing compound (I didn't). Clean with alcohol. Done.

i used 600 grit and moved up to 800 then 1000 grit. I just sanded in one direction for a couple passes, and then turned 90 degrees, sanded for a couple passes, etc. I heard circular motion lapping was bad.... but im not sure

stan03 said:

I heard circular motion lapping was bad.... but im not sure

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You know, I read somewhere that circular was bad also now that you brought that up. I did use the circular thing on mine though. Apparently some feel circular sanding leaves a convex surface.

I think that you will get a convex surface no matter what method of hand lapping you use. I did my stock AMD HSF in circular motions and because it was concave to begin with and it ended up flat - except for the very edge where bumping against raised paper rounded it off a bit. Just use a thick piece of glass with the paper on it and as long as you do the lapping gently with no real pressure in one direction then you should be all right.

I did mine with crappy 320Grit wet&dry - removed the milling marks well and flattened the base, but for smoothness go with 600Grit - bear in mind that if you skip a grade of sandpaper it will take twice as long with a finer grit to remove the lines of the last grit you used.

L337 M33P said:

I think that you will get a convex surface no matter what method of hand lapping you use.

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It won't get it perfect, but sanding in only one direction without rotating should give you a flat base.