Lapping

[rodrigu3]

So I know lapping makes the surface of the IHS or heat sink smooth, but how do you know the lapping job is level?

Not sure if this has any impact at all on the temp reduction one can achieve, but it's worth asking IMO.

Also, what would be the best way of spreading thermal paste once lapping on both IHS and heatsink is done? I've heard that thinner is better, especially for lapped surfaces. This makes me think that the procedure shown on the AS site is incorrect, being that too much compound is being applied. What do you guys think?

 

[genec57]

Write all over the surface with a marks a lot and then sand several strokes. If the ink is uniformly removed from the surface of the IHS or heat sink it is flat.
The AS instructions work well. If you want to be really anal about it you can put a thin line across one edge of the IHS and then spread it with a razor blade. This will give you a very thin, even layer.

 

[ctk1981]

Dykem - layout fluid for machinist is fairly cheap. Then again so is a sharpie marker. I bought a chunk of smooth/flat granite to use when doing the lapping. Luckily I get plenty of polishing paper from work...600-1000-1200. Would be nice if I could find some 800 there, but if not I can always buy some.

 

[Navid]

Originally posted by: rodrigu3
So I know lapping makes the surface of the IHS or heat sink smooth, but how do you know the lapping job is level?

Use a piece of paper and print a grid on it.
Look at the reflection on the surface.
http://i259.photobucket.com/al...id200/FlatnessGrid.jpg
If the surface is not flat at any point, the reflection at that point will show the straight lines as curved as you can see in this picture.
You can see the curvature at the edges clearly.

 

[bfdd]

blue dykem, use it all the time on the job, get a precision straight edge and you can check with that too, get a small one like a 6inch.

 

[rodrigu3]

the straight edge seems like the best idea to me. I know about the screen door test - that's for flatness not how level it is (by level I mean the flat surface can be tilted at an angle if the weight is not distributed evenly over the processor, but I think the difference is negligible).