First time lapping - Did I mess up?

I bought the kit from easypckits.com and started with 400, and spent a decent amount of time on 400, then moved to 600 then 800 and spent about 5 minutes on each, however as you can see in the picture, there is some stubborn nickel plating still on the bottom. Is that because I'm not doing it right? (I'm using circular motions as well as up and down motions) or is it because the base was uneven?

I eye the base and it seems straight to me. Is an uneven and dangerously so base easily seen with the naked eye?

http://kuonji.com/oc/IMG_2333.JPG

Since you're still on the mess in lapping that base, check out this thread HERE.

Hope it helps !






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You know what it is? I didn't tape down my sandpaper and kept dealing with it moving all over the place. Plus I think I wore out that 400 grit very quick, making it useless halfway through what I was trying to do. I think I need to pick up some more 400 and 600. Lots of it, so I can be sure to sand it down properly.

I think I heard a good tip for lapping was to put some water or some other liquid under the sand paper so it sticks to the glass when lapping. When I did it for the first time I used alcohol and regularly changed the alcohol when it got dirty.

I did put water under the sandpaper, It still slides everywhere. Tape worked. Too little, too late, though. Hopefully I can pick up grit this fine at home depot.

By the looks of the pic, your not even half way there yet. When you see only all Copper, then you can move to higher grid sandpaper. So stick with 400 till you only see all copper.

You need to buy a piece of glass, some 400, 600 girts at home depot. Then tape the sand paper on the glass, and sand the heatsink base against it till you see all copper. Finally, test the flatness against a razor blade or graph paper.