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PCViper UltraKit - Heatsink Lapping kit

Heatsink Lapping Kit
13th September 2004
Manufacured By
Supplied By



When the kit arrives it becomes clear you're not paying for the packaging. Suits me, it's not like you'll be using it again.

The Kit


The long strip of lint free cloth needs cutting into three pieces for use with each of the lapping compounds. I'm no textiles guru but this appears to be your reasonably expensive microfibre cloth which increases its effectiveness and greatly reduces its tendency to mark the surface.

The Kit


Finding a suitable subject to lap wasn't too difficult, though I figures softer aluminium was too easy and went for copper instead. Surprisingly, this woeful base is from the sink supplied in an AMD retail CPU kit. It came with the usual phase change gum applied which I had already scraped off.

The Candidate


PCViper recommend you mark up the base to give a quick indication of where the low spots might be. If you've seen our previous lapping reviews you'll know we've always done this anyway, but make sure you use a permanent marker. If you don't the water will wash the marks off when what you actually need is for the paper to sand them off.

Base Marked


Which paper you kick off with depends on the state of the base. I decided to go for the roughest 400 grit first though if you think you can get away with it go for the medium 600 or even the fine 800 grit paper.

My biggest complaint with this kit is that PCViper suggest you start by taping the sandpaper to a table. This might be okay if it's a good table but it's hardly the best way to get a precision flat finish. What you need is a piece of glass or a very hard, very true surface to work on. A table will do at a pinch, moreso if you're using an exposed core CPU as the smaller surface area is unlikely to be affected too much my small surface deviations, but for anything with a heat spreader fitted I'd try and find a piece of flat glass.

To be fair, PCViper explained that including glass would push up the price as the postal service insist it be shipped in its own protective box, not to mention the very real risk of it arriving in a greater number of pieces than it left in.

Before you start, choose a well lit location and lay out plenty of newspaper or tissues around and under your work area. Don't work on an important polished surface.

There's actually too much water on the paper in the shot below, I did this to make sure it showed up properly. Using too much water actually slows the lapping process by creating a skin under the base kind like a car tyre aquaplaning. It also makes it moor difficult to get a good, smooth motion going.

Circular motion or linear? There's a lot of argument over which is best and in my experience it doesn't seem to matter much. Linear seems a bit easier but you also collect more swarf under the base so choose which ever you prefer making sure you wipe the base with a paper towel and rinse the paper regularly.

PCViper suggest a linear motion to get started moving them a linear or figure-of-eight motion once you get into your stride. Some people swear that a linear motion gives a finer finish but having never compared the two I really can't say.

Paper Prepared and On Glass


After the first cycle on your starter paper, take a long, hard look at the base. If you still have pits, low spots or plateaus stay with the same paper. There's no point wearing out you next paper on flattening when it should be polishing. If the grit fractures and gets finer, and it will, use the edges of the paper more and use a linear action. At this stage you're still aiming to get a semi-smooth but more importantly, flat surface ready for the next stages.

If you've decided to do the entire surface as I did, then don't worry if the outer edges kick up and don't touch the paper. This is often the case and doesn't do any harm as it's not in contact with the CPU. If you want them to look good too you can sand them using the paper under your finger so they have the same finish. They just won't be flat.

After the 400 Grit


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