How I Lapped my Heat Sink

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DIY – Jeff G

I lapped my 9800 (stock) HS the other day just because I can – that and I’m picking up either an Artic Silencer or a Zalman VF700-CU in a couple of days (heck, maybe I’ll get both and write a comparison review). Anyhow, I thought I would share with you (pictures also) how I lapped my 9800 HS for those that don’t know how and even maybe give some new techniques to some that already do.

I would like to start of by saying

“I am not responsible nor is Overclockers.com/Forums for any damage that you may inflict upon your heat sink (HS). These are just guidelines on how (I) lapped my heat sink (HS) and should be taken as such (guidelines). What you do to your heat sink (HS) is your own responsibility.”

First off, get yourself the necessary stuff, most of which can be purchased at an auto parts store:

  • A flat surface – glass is best
  • 400, 600, 1000, 2000 Wet/Dry sandpaper
  • Masking tape
  • Jug of water
  • A sponge
  • 100% Cotton Terry cloths (important for secret ingredient)
  • Secret Ingredient (talked about later on)

I started off by taping a piece of 400 grit sandpaper to the flat surface (sticks well to glass), of a size at least 3″ bigger than the heat sink. I then proceeded to soak the paper with the water using a sponge – works good to soak up any spills also.

When the paper was good and wet, I started sanding the heat sink, at first using circular motions (clockwise and counter clockwise), but found it did not leave a desired finish. I then started sanding in one direction back and forth a dozen times, then turned the heat sink 90 degrees and proceeded to sand the same amount of times again.

Here is what it looked like after the first few sanding with the 400 grit.

Lap

As you can see, the heat sink started to show sanding marks on the edges first, meaning this heat sink was not all that flat.

After I sanded off all the black paint (damn stock HS), I changed to the 600 grit, again taping it to the flat surface and soaking it with water.
Here you can see in the center and just above it that the heat sink is still not flat; not to worry, as the 600 and 1000 grits of sandpaper will get this out. This one is after the 600 grit.

Lap

Again the same procedure for the 1000 grit…

Lap

Now here’s the point where I did something a little extra (Special Ingredient)…

After I used the 2000 grit for awhile, I was not satisfied with the finish (don’t get me wrong – it was good, I’m just picky). So what I did was used a product (2 actually) called Meguiar’s – it’s a high grade professional car finish product (I used them for years to give a mirror finish).

The first one I used is called Final-Cut Cleaner; I applied it with the cloth as per instructions on the bottle and then finished it off with the other one called Swirl Remover, again as per the instructions. I then cleaned off the heat sink with Isopropyl Rubbing Alcohol with a separate cloth. Making sure the heat sink is fully cleaned (until no more color appears on the cloth.) Allow for dry time before reinstalling.

The results, I’d say are outstanding.

Lap

I hope this helps even just one person. Good luck & Happy lapping!

Cheers

Goli

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Discussion
  1. Apparently several people dissagree with the authors methods and terminolgy, understandble so, there is a disclaimer though.

    Like any article though it is subject to scrutiny, I don't understand the out right bashing of it though, or the questioning of front page worthiness.


    I done agree with bashing either, as if you can do a btter job, prove it and stope bashing.

    I know that was never intended to be a front page article, as that is not how it was written, not inteneded for teh front page.... However he should be picking up a new heatsink (CPU) this weekend and has told me he is going to do the step by step with proof for it with enought detail that should satasfy the people here.
    I'm confused what everyone is arguing about.

    And what does this have to do with the article in question?

    If this is all about the cut polish he used at the end, well it was and its residue all removed at the end, so only metal was left


    Apparently several people dissagree with the authors methods and terminolgy, understandably so, there is a disclaimer though.

    Like any article though it is subject to scrutiny, I don't understand the out right bashing of it though, or the questioning of front page worthiness.
    As much as this topic has been tossed around, I would have thought everyone would have known these facts. Shiny is NOT flat, Shiny isn't any better than not shiny as far as heat transfer is concerned either. Lapping does not make a heatsink shinier it makes it flat. Shiny may be smoother but this can be detrimental to the effectivness of the thermal compound. Now on the other hand it is possible to mate your heatsink with the cpu, by polishing one with the other using a compound made for such polishing, thereby getting a surface so smooth and shiny it doesn't even require a thermal compound. But not flat.

    It has been my personal experience that using anything past 1500 grit sandpaper nets no significant gain in thermal transfer. This finish also gives the thermal compound something to hold onto.

    Polishing the bottom of a heatsink is like doodling, lots of people do it, doesn't mean everyone should. Does it help heat transfer? Not from my experience. Like doodling though it will keep otherwise idle hands busy, and you know what they say about idle hands.
    Yes, shiny doesn't equal flat. But what he's trying to say is that most of the time, when you lap a heatsink, it ends up flatter AND more reflective.
    arrrgh, go lap 2 heat sinks right now, one left stock, next one done up a few times with different grits, going up every time. I told you that you can go polish anything, i can polish a spoon that doesn't mean its flat, when an HS is lapped it has a slight shine to it. its like i keep repeating my post and you guys censor out all my writing except the words: flat, shiny. Jeez, show me a pic of a stock HS, then lap it take a look at both HS's you'll see.


    I can take a quarter, sand down all the edges....but that doesn't make it flat.

    You have to be careful NOT to associate flat and shiny. Shiny, definitely means "smoother", if you will, but if you didn't do it on a flat surface, you have something that is shiny and NOT flat.

    If done correctly, yes. But there were posts suggesting that since it is shiny, it is therefore flat; that is incorrect.
    arrrgh, go lap 2 heat sinks right now, one left stock, next one done up a few times with different grits, going up every time. I told you that you can go polish anything, i can polish a spoon that doesn't mean its flat, when an HS is lapped it has a slight shine to it. its like i keep repeating my post and you guys censor out all my writing except the words: flat, shiny. Jeez, show me a pic of a stock HS, then lap it take a look at both HS's you'll see.
    I'm confused what everyone is arguing about.

    And what does this have to do with the article in question?

    If this is all about the cut polish he used at the end, well it was and its residue all removed at the end, so only metal was left
    Censor, you've tried. I've tried.

    Sometimes, some people just don't get it

    Shiny = shiny.

    Flat = flat.

    Shiny doesn't = flat.

    Flat doesn't = shiny.

    steve
    argg :bang head

    "there is no correlation between reflectivity and flatness."

    This is true. This can be reflective and flat, but that does not mean that something that is reflective is flat.

    "i.e. one cannot show a picture of a highly reflective base-plate, like most web-sites do, and then make any assumption as to its flatness and hence its suitability to make good thermal contact against a CPU."

    Quotes by Cathar.
    9mm please carefully read my posts, go lap 2 identical sinks, don't polish em and show me results, if you want i'll do it to prove my point. There is a correlation but not always direct.
    Yes, I stated that as well... unless I said it in the other thread about the front page article. Basically, I was saying that shiny can be associated with smoothness (as long as there are no chemicals involved). Smoothness does NOT have anything to flatness. Something that is curved can still be smooth, but it doesn't mean that it's flat. As long as it's smooth, I think a curvativity of zero = flat, no?
    if he lapped it and got it that shiny then im sure it would be flat.


    No, thats the problem.

    Saying something is shiny means it will be flat is not correct. There is not correlation between shiny and flat.