Heatsink Lapping attempt

[rpertusio]

I just wanted to let you guys see my latest project: Lapping my heatsink! (And I took pictures!) The theory behind lapping is that a flatter/smoother surface promotes better heat transfer. Better heat transfer means your CPU runs cooler.

I discovered a Heatsink Lapping Kit from David Brown at Easy PC Kits, and I thought I would try it on a heatsink that I no longer used. The lapping kit is pictured below:

(click to enlarge)


Victim: Copper base from a ThermalTake Volcano 11

Here's the BEFORE shots. (The heatsink looks very much like this when it comes from the factory):
- and -
(click to enlarge)


Then 90 minutes later, I ended up with a nice flat shiny piece of copper:
- and -
(click to enlarge)

I opted to lap it in straight lines rather than circular (or figure 8) motions. I've seen people argue about which one is better. My next heatsink I will lap in circular/figure 8 motions and see how different it is.

I haven't tested it, so I don't know how much of a temperature drop it made. (This is an extra heatsink I don't need.) At some point, I'll get around to doing the same to my current heatsink (TT SilentBoost)

Hope some of you found that interesting!
- rp

[Edit: I can spell, honest!!]

[thekingofpain]

Came out real well, hope that sack of white powder wasnt your driving force behind all that work :-)
I dont do it anymore---seems like the manufacturers have "smoothed things out" and products like Arctic Silver now assist in filling those microscopic finish flaws---we used to do it because it looked like they chucked a rock in the milling machine to finish the heatsinks surface...
no more blisters for me

[jmoore2001]

yeah i thought the purpose of the thermal compound was to fill the microscopic valleys? if you take those out then it wont cool as good?

[rpertusio]

Originally posted by thekingofpain
hope that sack of white powder wasnt your driving force behind all that work :-)
I dont do it anymore

You don't do the white powder anymore, you say? j/k (Actually, the bag contains a little bit of polishing compound, not exactly powder)

products like Arctic Silver now assist in filling those microscopic finish flaws

You bring up an interesting point... should Arctic Silver even be used when the heatsink is lapped, or would it 'get in the way' of the heat transfer?

from jmoore2001
yeah i thought the purpose of the thermal compound was to fill the microscopic valleys? if you take those out then it wont cool as good?

Thermal compound (I 'd think) wouldn't conduct heat as well as the copper heatsink would. By lapping, more of the copper would touch the core of the CPU, and thus would allow heat to transfer more efficiently. (ie.. less need for the less effective thermal compound. just my theory)

by thekingofpain again
we used to do it because it looked like they chucked a rock in the milling machine to finish the heatsinks surface...

I can't speak for other manufacturers, but I think ThermalTake still chucks rocks in there. The heatsinks are coming out with more shine to them, but I wouldn't consider them exactly flat. (It seems like they add a polished compound to the surface to give the impression it is flat.)

- rp

[Uncle Bob]

By lapping in a straight line you did not lap the surface you polished it. I think you'l find that the"lapped" item isn't as flat as you think.