Lapping?

[thenebulouseffect]

What does lapping a heatsink do, I'm totally lost as to what it means.

 

[mechBgon]

Lapping the heatsink flattens its base (primarily) and smooths its base (secondarily), so that it doesn't take as thick of a layer of thermal grease to bridge the microgap between the CPU and the heatsink. The thinner the layer of thermal grease, the better the heat transfer across the layer of thermal grease and the less temperature difference will be required to drive X amount of wattage across it.

edit: if you meant "how is it done," the usual method is to lay wet/dry sandpaper on glass, put some water on it, and gently swirl the heatsink around in a figure-8 pattern, progressing from maybe 400-grit up to 1500-grit.

 

[pirred908]

I've had better results just moving the heatsink in a straight, back and forth motion. It smooths faster. Also, I would use up to 2000 grit.

 

[SilversinkSam]

If you can't find lapping supplies locally, Check out http://easypckits.com/

He offers excellent prices and the owner Dave Brown is a real nice guy that goes the extra mile for his customers. Tell him Silversinksam sent you and he'll charge you double


Edit: Almost forgot, He sends excellent instructions with each kit.

 

[gotensan01]

I don't know about lapping. I lapped all three of my water blocks (cpu, gpu, and nb) going from 1000 to 2000 grit because they were in really good shape to begin with. In retrospect I think I would have just cleaned it with alcohol and left it at that.

I'm just not convinced that any person could lap better than a machine. Machines can make real flat serfaces whereas I think people make what looks like flat surfaces.

Btw, I did use a piece of glass and water for the process. I did a combination of circles and straight back and forth. However I only lapped each block for probably a total of 15 minutes. In the end I probably did nothing to it other than remove some surface dirt.

 

[SilversinkSam]

Originally posted by: gotensan01
I don't know about lapping. I lapped all three of my water blocks (cpu, gpu, and nb) going from 1000 to 2000 grit because they were in really good shape to begin with. In retrospect I think I would have just cleaned it with alcohol and left it at that.

I'm just not convinced that any person could lap better than a machine. Machines can make real flat serfaces whereas I think people make what looks like flat surfaces.

Btw, I did use a piece of glass and water for the process. I did a combination of circles and straight back and forth. However I only lapped each block for probably a total of 15 minutes. In the end I probably did nothing to it other than remove some surface dirt.

Some manufacturers like Swiftech implement a special machine to produce an ultra flat base and no amount of lapping can improve the Swiftech process. In fact by lapping it, you are making a mistake

But most manufacturers don't produce a base a well finished as Swiftech's. One way to determine the finish is by rubbing your fingernail over the base. If you can feel any grooves or ridges, Lapping cannot hurt and is a good idea.

 

[Navid]

Lapping can hurt really bad!

If you don't do it right, you will create a convex surface (like the outside of a sphere in exaggeration).
Then, the contact area will actually decrease, which is not what you want.

Lapping will pruduce a smooth surface. But, a rough flat surface is better than a smooth convex one.