Don't laugh: Should I lap PAL6035



New Member
I beleive I'm going to have to lap my PAL6035 because it has some scratches and dark spot on the contact surface. The temps are rather high after I got my replacement CPU since I crushed my first one. There's a strange spot on the surface where it made contact with the TBird die that almost looks like a scortch mark.
I've never lapped a copper based HS so I'm worried about it. How much will it wear it down? Should I do it or just buy a new one?
Also, I was considering using auto rubbing compound. Have a friend who used it on his and he said that it worked great on his HS. I have a kind that says it will remove 1500 grit scratches or finer. I'm mentioning this to try remove debris and any air pokets in between.


Copper will grind down very fast, the smoother the surface the better. Use compound
instead of paper!! I would think a fine micron grit such as 14.5 particle size should
be good enough. What do you have to loose if you don't try it, you can always buy another!
Use a piece of Plate Glass to do the work!
Oh grind in figure 8 motion! Remember flatter is Better!

If you cant get some descent grinding compound send me an email and i will deliver
some to you at cost of shipping only!

[This message has been edited by Warbird (edited 04-13-2001).]

[This message has been edited by Warbird (edited 04-13-2001).]

[This message has been edited by Warbird (edited 04-13-2001).]


New Member
Thanks for the offer Warbird, will keep in mind. I already started off with a 600 grit paper and sure enough the edges are all buffed but the center is barely touched. I'll keep you in mind of I need a good compoud. thanks


New Member
Nothing to laugh at. Lapping the HS will help, but your biggest concern should be getting that heatsink flat against the cpu slug when you mount it. A dark scorched area, high temps and crushed cpu are symptoms of an improperly mounted HS. Ensure you check this out or you will be back to sguare one.


New Member
If the center is barley touched you are probably not keeping it flat enough while you lap. Try to put some pressure in the exact center of the HS.

I like to lap in one direction for a while and then in one direction 90 degrees from the first. I think it is easier to check for flatness and to see when a finer grit has removed all scratches from the previous grit that way. Maybe do the final polishing with a figure eight

You can get wet or dry paper up to 2,000 grit at most auto parts stores.

Good luck with it, Bill

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I say only do the polish in a linear motion. My experience is that anytime you start going in circles you are going to make it round instead of flat. When you go in a linear motion(ie back and forth or side to side) it should take down the same amount all around. I have used 1500 grit sand paper to do this and stuck it to my counter top with water. A good super fine sharpening stone would be good also. I like the plate glass idea for final polish though. Never thought of that one.I have done this to three different heatsinks. At first I did the circular motion and that caused it too be round instead of flat. I question but I may be wrong about the figure 8 motion doing the same. For a final light polish though as has been stated a figure 8 should be fine but a linear still might be best. Good luck.

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New Member
I lapped my 6035 using 250 grit all the way to 800 grit and it resulted in a 2C temp drop

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luta wicasa

New Member
What I've read of other's posts, they are all right to an extent. Use a flat surface(I use a good mirror)start coarser grits(500)in a back and forth at 90 degree to each other(straight cuts and at 90 to each other will remove more material)Once you have the sink flat you will want to do your final polishing in a circular or figure 8 motion(1500-2000) If ya use a rubbing compound be sure to clean it very well before application of AS or whatever thermal goop you'll use. Or you can use AS when you sand. When done you should have mirror like finish with a clean reflection(no waves) Have fun

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New Member
Interesting luta. Is the purpose of useing AS while sanding to make sure no other material gets in the heatsink?


Interesting comments, A Figure 8/Linear motion probably will make no difference. If the work surface is either convex/concave the piece will always come out the opposite. Since the only area involved here is about
1/2x1/4 its not really necessary to get the whole HS flat. Just the center!!
But it is important not to include any type of scratches/digs on the surfaces!

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