Wet or dry lapping?

[tigersty1e]

So some guides out there say to wet the sandpaper and lube the heatsink/cpu and then proceed to lap...

Others say to just lap without any water...


What's the difference?

 

[Burrich]

Lower viscosity when sanding. A guide I read (and used) said you should tape sandpaper to a table and work in a figure 8 pattern. Using a table will ensure a flat surface, the figure eight would allow you to go from many different directions to remove a one-sided sanding job.

 

[tigersty1e]

It seems like wet is the way to go.

Unless someone can make a case for dry lapping...

 

[Glavinsolo]

what the hell is lapping

 

[Burrich]

Sanding a surface so it becomes flat. You do this to heatsinks (mostly) so they are flat and have better contact to a chip and have better heat transfer.

 

[Quiksilver]

What would be the best liquid to use while wet lapping anyway? Considering I will be lapping both heatsink and cpu; luke warm soapy water doesn't seem like the best choice.

 

[tigersty1e]

I was thinking of using a drop or 2 of dishwashing liquid.. apply as needed.

 

[Tweakin]

If you look at lapping in a larger sense, such as auto body work, most rough work is done dry. Only the final stages are done wet and this is to ensure the removed particles are not stuck to the sanding surface.

I use dry for 220 and 400, then go wet for 800 and 1200. As for the wetting choice, I use isopropal alcohol. It will not damage the cpu if you get it wet and it does not leave puddles on the paper as it evaporates slowely.

 

[Burrich]

I've never used alcohol as a wetting agent, I've only used water with some dish soap.

 

[Idontcare]

I lapped a handful of G0's and Tuniq's here a couple months ago and had the same question.

So for one I used water, another I used dishsoap, another I used a mix of the too, and of course one I did dry.

By far the fastest easiest way (for me) was the dry method. When I got liquids involved things jsut got crazy messy to control and the cleanup took more time than I was finding to be worth it.

The only technical reason you wet sandpaper is to reduce loadings. I.e. if you want to increase the lifespan of your sandpaper and decrease your sanding time on any given grit.

Some folks swear that the added lubricative effect of wetting the paper helps prevent "skipping". I wish that were true, in my case the effect of wetting the paper was to cause my Tuniq to "stick and pop" across the paper like a suction cup sliding across a wet shower wall.

In the end I just went with dry sanding for everything but the top grit level (1000 grit in my case) and I was happy for the remaining Tuniq's and G0's I was lapping.

I think it really is a personal choice and comes down to your sanding style and the amount of downpressure you are going to end up using by way of your natural arm positions and so on.

Lapping is definitely not a "one size fits all" when it comes to technique and approach.

I found Graysky's lapping guide to be a great reference, reading it gave me the courage to finally try lapping and I haven't looked at a CPU IHS or HSF the same since!

 

[aigomorla]

Originally posted by: Glavinsolo
what the hell is lapping

Making the cpu as flat as possible. By doing so, it tends to even out core temps on quadcore and lower temperature overall on the IHS.

Havent seen that big of a benifit unless having both the sink and ihs Lapped.

Example of a Lap Job, not the kind you get at a strip bar:
http://i125.photobucket.com/al...aigomorla/IMG_0569.jpg

Another one which the forum seems to like this this one:
http://i125.photobucket.com/al...aigomorla/IMG_0703.jpg

Mirror finishes are optional. I do it because i dont like cutting corners on my main build.

 

[Cookie Monster]

Heres a good guide to lapping.

Link