Best way to lap a heatsink?

[louie2001]

I am very familiar with lapping and what it's purpose is for,just wanted some ideas from people who have already done their heatsinks.I have spent hours lapping steel barrel and plungers for fuel injection pumps but not tried aluminum yet not for sure best way.It is on a Swiftech MC370-0A Thanks

Rock out with your AMD out

 

[gregorarch]

Lapping aluminium is pretty much like lapping anything else - you just have to be a bit more careful because it's softer. Tape your sandpaper to a sheet of glass for maximum smoothness. Be very careful to apply even pressure, or you'll end up with a crown.

For the final mirror finish, polish with a cutting compound (like T-Cut or something).

I got an extra 50 MHz from my K6-2 just by lapping the sink.

 

[Guest]

When working with aluminum, I have found the best cutting fluid to be good old WD-40. It will keep the paper cutting nice and clean and will stop pick-up. There are other fluids but WD-40 is so easy to get.

 

[louie2001]

Thanks I use figure 8's to keep the surfaces flat. What grade of sandpaper or emery would be good to start out with and end up with?

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[Guest]

I haven't done my heatsink yet but I am a tool and Die maker from a while ago. You will probably want to start with 600 grit and then work down to 2000 or so.

The trick is to remove all of the scratches from the previous grit. If you can work in one direction and then go the other way when you up the grit you should be able to view the scratches that are left behind. So, I guess that for hand lapping, I would recommend figure 8s for the rough removal (if there is any) and then go to linear, one direction paths for the finals going 90 degrees to the previous each time.

 

[kurokaze]

600 grit to 2000?

egad.. when I lapped my HSF I went from 100 grit to 150 and then to 220. And it was fairly smooth and shinely by the time I was done with it..

 

[Pettytheft]

Damn no kidding I used 600 as my finishing grit.

Truth is I've never even seen anything over 800 at the store.

If you take a truth and follow it blindly, it will become a Falsehood and you a Fanatic.

 

[louie2001]

You can get higher gritt at a auto parts store or body shop, and I have seen up to 2000 grit.The way everyone discussed is the way I thought, but just needed some reasurance thanks to all.

Rock out with your AMD out

 

[Guest]

Yeah, if you use a good cutting fluid, 600 will cut really fast and give a nice shiny surface. If it is really bad though, you can start with a 220 or so; no coarser. I would consider 600 as the minimum you would want to get to.

I think that papers will go to about 3000 or so. Not sure though.

 

[Guest]

If you go to any decent hobby shop, you will be able to pickup plastic wet/dry sheets of 4000 grit and above. Testors makes a paint finishing kit that includes several of these sheets, ranging from about 1000 up to around 6000 or so. I'd recommend starting with around 220 if the surface is very rough, then wet 220, then 400, wet 400, 600, wet 600, then either those plastic sheets or a polishing compound. the 4000 grit plastic sheets weren't really made for metal, so I'm not sure how long they'd last, and they're expensive. I think after 600 grit polishing compounds make the most sense. If you want a very mild compound, chrome would be good, silver polish is probably the softest you'll find. Just my $.02

3C2X1(<b><i>Genius</i></b>).
Even though I'm a stranger, at least my average post is intelligent!

 

[louie2001]

Thanks I was thinking 600 grit then 1000 then use some neverdull on it to polish it to a mirror finish.I think 600 will probably be as coarse as I will need I would rather take more time than puit a bunch of deep scratches in it then spend a week getting them all out.

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