How to lap properly?

[The Doors]

Hi guys,
a simple question: the sandpaper must be used wet or dry to lap the bottom of an HeatSink?
My question coz, with an Alpha Pep66 and a Great case airflow, the chip temps aren't very good, around 45 degree C @full load!? and I've checked everything (for sure!), but not this way :D

Thanks for your support :)

[Ridenow]

The prefered method uses wet sandpaper stuck to a piece of glass. Other methods also work with dry sandpaper.

[The Doors]

Thanks Ridenow,
I did it with sandpaper (grain 800, 1200 & 2000) dry on a nice glass of a picture :) but I'll try that with a wet sandpaper, I hope will improve the Hs cooling, still many thanks ;)

[Warlord2]

wet shouldnt make a difference or atleast a noticable difference

all wet does in remove all the copper from the sandpaper so it lasts longer

[The Doors]

Uhmmm, at this point I'm a little confused,
probably is the grain 2000, I'll try with a final polish with wet sandpaper grain 1500.

Thanks for your support Warlord2 ;)

[Patchmaster]

This is getting down to the nit picking stage, but since you've already lapped with 2000 grit you're obviously there anyway. After you've used the 2000 grit to create a mirror-like finish, resist the temptation to continue with some kind of polishing or buffing compound. Use acetone or 91% isopropyl alcohol (NOT rubbing alcohol) to clean off any remaining residue (or, better yet, use some compressed air to blow it off) and let it dry thoroughly. Make every effort not to touch the lapped surface with your fingers. Put on a clean rubber glove (put a plastic bag over your hand if you don't have any latex gloves) and massage some thermal compound, preferably Artic Silver II, into the heatsink. You want to work the thermal compound into all those microscopic nooks and crannies. Then put a very thin coat of thermal compound on the top of the CPU and mount the heatsink.

[Oni]

When lapping, I prefer wet paper because you get a better cut w/ less work. On the final pass, though, I'll clean it off w/ alcohol, let it dry, then dry sand w/ some ASII. Comes out real nice and shiny!

[Tbird man]

I am a perfectionist so i plan on using a polishing kit for 1/24th scale models which includes 6000-12000 grit polishing paper and compound i want this thing to be FLAT!!! but i guess you will probibly say that is excessive but all i can say is hay, have you ever tried it?

[spooge]

if your lucky enough to know a MoldMaker, ask him
for some diamond compound. This is used for polishing the core/cavity to get a mirror finish. this way clear plastic parts
WILL be clear( no scratchs). This stuff is very abrassive ! And you can start with a 600 finish(before using).

[JAWS]

Originally posted by Tbird man
I am a perfectionist so i plan on using a polishing kit for 1/24th scale models which includes 6000-12000 grit polishing paper and compound i want this thing to be FLAT!!! but i guess you will probibly say that is excessive but all i can say is hay, have you ever tried it?

Where do you get that polishing kit from?

[Patchmaster]

I am a perfectionist so i plan on using a polishing kit for 1/24th scale models which includes 6000-12000 grit polishing paper and compound i want this thing to be FLAT!!! You're losing sight of the objective. Unless you plan on entering this year's "I can see myself in my heatsink" contest, the point is to get maximum thermal transfer between the CPU and the heatsink. No matter how much time you spend polishing, there are going to be microscopic hills and valleys on the surface. If you use polishing compound or any kind of petroleum based product it's going to get into those valleys and there is no way you're going to get it out. You want thermal compound in there, not polishing compound. The 12,000 grit paper is fine (though severe overkill), but forget about the polishing compound. Do like Oni said, use some AS II for your final polish. At least you'll end up with thermal compound filling all those little microscopic holes.