question on smoothing out heasink

[angrysquirrel]

Hello,
I have a used coolermaster cooler master kcu-7025 (copper heatsink with aluminum fins).

It has some scratches on the heatsink and I've heard the term "lapping" used when it comes to smoothing out a heatsink.

What do you guys use buff out the scratches on the copper to make the connection even with the CPU? Would you use sandpaper? What grain would you use? I was thnking of using a block in conjunction to make sure the sanding is uniform. How about a steel wool pad? Thanks for your help!

 

[Silver]

Steel wool is out. Use 600 grit on a piece of glass or as Hoot has stated (works too - I should have thought of it) the formica counter top in the kitchen. Use the sandpaper wet and rinse it often. You are looking for a uniform FLAT surface and thus steel wool is a no, no. Sand paper at 600 grit is available at walmart and most automotive parts stores. Check in the paint section. Hardware stores usually do not have it this fine as much of theirs is for finishing wood.

 

[angrysquirrel]

thanks silver!

That has got to be the FASTEST response I have ever gotten on a newsgroup! You guys are great! I'm gonna head down to wallmart tomorrow and see what they have for sandpaper!

 

[Illah]

Don't JUST use 600.

I used 400 for the first sanding just to flatten it out, then 600 to smooth it, the 1500 to really smooth it.

If you really want a mirror do 400, then 600, 800, 1000, 1500, then polish or buff it. I'm not a lunatic so I can deal with a super smooth yet not quite a mirror heatsink. As long as I can't feel a thing when running my fingers across it and it's pretty reflective I'm set.

--Illah

 

[eobard]

I don't recommend using your kitchen counter top but not for the effectiveness of the lap. With all the anecdotal evidence that aluminum contributes to Alzheimer's disease I wouldn't want to have snotfulls* of aluminum dust floating around my food prep area. But if you have a slab of spare counter top sitting in the garage is should be flat enough.



* A "snotfull" is a metric measurement. Unlike most measurements snotfull can quantify both distance and volume.

 

[angrysquirrel]

so should I put the sandpaper on the countertop

and then run the heatsink across the sandpaper?
I will get different levels of sandpaper for a good smooth surface.

Thanks again folks!!

 

[Silver]

Don't JUST use 600.

I used 400 for the first sanding just to flatten it out, then 600 to smooth it, the 1500 to really smooth it.

If you really want a mirror do 400, then 600, 800, 1000, 1500, then polish or buff it. I'm not a lunatic so I can deal with a super smooth yet not quite a mirror heatsink. As long as I can't feel a thing when running my fingers across it and it's pretty reflective I'm set.

--Illah

I tried to stay away from this on the first go. There are varying opinions on this. I am one of those that happens to prefer the use of the higher numbered paper. I like and have had better results with 12 to 1500 final. I have used 2000 on occasion. On the first go he is right on starting off with 400 and you could finish with 600. Kind of helps the budget. As for the aluminum there has been mounting evidence to this effect. However I have seen no evidence to this effect on copper. BTW much of todays cook ware is aluminum. The bottoms and some cook ware are made of copper as it causes a more even heat distribution however its' cost is rather high for cookware.

 

[Illah]

As for aluminum poisoning, that's why you wet everything down. No dust flying around and easy cleanup. Whatever microscopic aluminum or copper particles are left on the countertop, all I have to say is who the hell just hunks down meat and veggies right on the counter to prepare food? That's what cutting boards are for.

--Illah

 

[Lt. Max]

what grit is normal paper? i mean 600 is high , i think (never seen higher) and ur talkin 2000 here.. is paper like 3000?

 

[Illah]

With 1500 grit you can barely feel the 'sand' on the 'paper', even if scraping it with your nail. It's pretty cool.

If by 'normal' you mean sandpaper meant for wood you're talking 200 grit or less. Some of the chunkier wood sandpapers are like 8-12 (they are the ones with the big *** pebble looking things on it).

--Illah

 

[Istari1]

Also someone said "polish", DONT polish it with any kind of metal polishing solution. This stuff will fill up wicro crevices and cause poor heatsink performance. Just use the highest grit you can find and then clean it with alcohol. If you use 1200 or so you shouldnt even need polish to see an almost mirror finish.

Josh

 

[Ugmore Baggage]

Remember that when sanding a flat surface with another flat surface the tendency is always to cut more at the edge. That means that unless you're perfect, and your "flat" surface is also perfect, you'll wind up with a slightly convex surface. I think that if you use circles (which I have seen recomended) you'd have even greater error, because it would add twisting error from your wrist -- when you twist, the edges would move (therefore grind) further.

Does lappiing make a difference if you don't remove the lettering from the core?

 

[Intraveinous]

what grit is normal paper? i mean 600 is high , i think (never seen higher) and ur talkin 2000 here.. is paper like 3000?

Yeah, 600 grit is pretty high for the average joe who never sands anything but wood. Higher than that is normally used as a finishing sand for car body work etc... I've always bought my sandpaper at the local auto supply shop, and got 3M Imperial WetorDry brand. You can get it in up to 2000 Grit, which is pretty darn fine... I never went above 1500 though... It has been suggested that above 1000ish you start hitting diminishing returns.
As for your second question, paper, depending on the content, finish, etc, can be anywhere from 1800-3500 grit equivalent... There are many HIGH END (think Rolls Royce, etc) body shops that use an absolute final sand with sheets of ordinary copy paper after working their way from 400 up thru all the different grades with a coat of paint inbetween each wet sanding.
Peace
John

 

[angrysquirrel]

got my sandpaper

and I'm sanding like a madman. Only problem is that the goue still seems to be there. Do any of your know of any heatsinks that are supposed to have a round circular mark in the center of it? Maybe it's used for cpu placement? Also, if put some kind of compound in there like artic silver, would this take care of any gouges like this as far as heat goes? Or do you guys still think I should sand until I can get this baby gouge free?