Lapping

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Kr1z

[H]ard|Gawd
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Nov 1, 2007
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2.75 x 4.5 sheets of wet-or-dry sandpaper
- 4 sheets of 220 grit
- 4 sheets of 400 grit
- 4 sheets of 800 grit
- 4 sheets of 1200 grit
- 4 sheets of 2000 grit
- 4 sheets of 2500 grit

One (1) 3" x 4" lapping surface

Just got my sandpaper lapping kit today.
I'm having trouble finding which one is the 220 grit? Is it the really rough one?
They get smoother as I go up right?

I plan on lapping today, and need some tips on how to do it right and make the surface as flat as possible.

From reading many lapping guides I picked up these little tricks

taping the sand paper to a glass and lapping it like that

the credit card and razerblade method to determine the flatness

coloring the surface with a sharpie

any more that I can add?

Also which layers am I going to have to sand off? What colors are they?
One drop of water is enough to wet the paper?and how much time should I spend on each grit?



I'll be lapping the heatsink first then my CPU.

Tuniq Tower 120 and Q6600.
 
the roughest will be the 220, the 2500 should feel almost like a sheet of paper without any roughness at all.

Where did you get your lapping kit as I too am looking at doing this for a few parts.

:)
 
Why so many sheets of sand paper? I used less than 2 sheets of 400 grit when i lapped my TRUE and q6600. Also, there really isnt much of a reason to go for that super super shiny finish, your focus should be on FLAT. My temps came down around 14C on my outer cores and around 5C on the inner cores and i only lapped using 400 grit.
 
You can easily find decent sized sandpapers at an automotive store, such as Autozone, Pepboys, etc.

The lapping kit that svc sells are a bit too small for my tastes...
 
veedubfreak said:
Why so many sheets of sand paper? I used less than 2 sheets of 400 grit when i lapped my TRUE and q6600. Also, there really isnt much of a reason to go for that super super shiny finish, your focus should be on FLAT. My temps came down around 14C on my outer cores and around 5C on the inner cores and i only lapped using 400 grit.
Click to expand...

Focus should definitely be for a flat surface, but do realize that finishing off with a low grit will leave alot of tiny scratches all over the surface.
Sure the thermal compound should fill all those micro-valleys but if you're lapping in the first place - might as well minimize the scratches left by the lower grits.
Also, look at how small those sheets are. 2.75" x 4.5 doesn't give too much room to lap comfortably.
 
I don't care about it being shiny, just flat, I won't be seeing the CPU or heatsink anyways so what is the point.

How do I know when I reach the layers I have to sand off?

In the meantime I will try to lap the stock intel cooler to get some pratice.
 
Kr1z said:
I don't care about it being shiny, just flat, I won't be seeing the CPU or heatsink anyways so what is the point.

How do I know when I reach the layers I have to sand off?

In the meantime I will try to lap the stock intel cooler to get some pratice.
Click to expand...

You aren't trying to lap off any layers, just get it flat. If you lap the chip you will quickly sand through the silver-colored layer and into the copper material underneath, but it has been my experience that it takes a long time to get to solid copper, if that's what you wanted to do.

I think the marker idea is a good one - I've never heard of that before but it sounds like a good idea.
 
Also amazon.com has full paper sized sheets. I already have a nice glass surface I can use.

But that place is at least in the US so it may not be that bad. The sheets are a bit small but still nice to see a US place to get them.
 
Have fun!

I thought it would be fun...and not that hard...but it was a pain in the ass.
 
Something that has always bothered me about the idea of lapping... Is it possible to lap to far such that the processor and heatsink will not make good contact anymore? Like if you were to lap, and then the computer chip would not stick out far enough from the socket? Does anyone understand what I'm talking about?

Thanks.
 
I dont think that can happen :O

How much force should I apply when I use the 220 and 400 grit?
Do I have to wet it or just lap it dry?
 
blade52x said:
Something that has always bothered me about the idea of lapping... Is it possible to lap to far such that the processor and heatsink will not make good contact anymore? Like if you were to lap, and then the computer chip would not stick out far enough from the socket? Does anyone understand what I'm talking about?

Thanks.
Click to expand...

I think it would take a lot of lapping for that to happen. You're not really taking much material off, the most you're going to do is lessen the amount of force the heatsink contacts the chip with - and even then probably not enough to even notice.

Kr1z said:
I dont think that can happen :O

How much force should I apply when I use the 220 and 400 grit?
Do I have to wet it or just lap it dry?
Click to expand...

It's easier to lap wet, less resistance. Don't press too hard, but not too soft either - kind of difficult to say, just do what feels right.
 
What else can I use to determine the flatness of it? I tried lapping yesterday and got to the copper layer on the IHS, but I couldn't get it flat with the razerblade, I kept on seeing light from the flashlight in between.

I also did a good 30 minutes of lapping of the heatsink.

I placed them back in the system because I was tired, and the temperatures are exactly the same.

I will do it again tommorow when I have more time. I don't think I lapped enough at all. I was scared to press hard on the surfaces :/
 
it can happened, happened with my friend on a Q6600 and Thermalright u120 extreme, fixed it after though, made the temps go past 70 easily.

don't apply any force, let the weight of the cpu and heatsink do the work, I just did mine, i'll post pics tomorrow.
 
Kr1z said:
What else can I use to determine the flatness of it? I tried lapping yesterday and got to the copper layer on the IHS, but I couldn't get it flat with the razerblade, I kept on seeing light from the flashlight in between.

I also did a good 30 minutes of lapping of the heatsink.

I placed them back in the system because I was tired, and the temperatures are exactly the same.

I will do it again tommorow when I have more time. I don't think I lapped enough at all. I was scared to press hard on the surfaces :/
Click to expand...

Unfortunately, if the heatsink is already flat then lapping it won't do much good. I don't think you are ever going to get it flat enough not to see light through the crack, photons are pretty small after all, but it shouldn't have a big gap. Did you check it's flatness before you started? You also probably need to lap the heatsink, they are often even worse than the IHS.
 
Kr1z said:
What else can I use to determine the flatness of it? I tried lapping yesterday and got to the copper layer on the IHS, but I couldn't get it flat with the razerblade, I kept on seeing light from the flashlight in between.

I also did a good 30 minutes of lapping of the heatsink.

I placed them back in the system because I was tired, and the temperatures are exactly the same.

I will do it again tommorow when I have more time. I don't think I lapped enough at all. I was scared to press hard on the surfaces :/
Click to expand...

In the end lapping is only really recommened for heatsinks that don't have perfect bottems. Easy way to test this is this.

Take a peice of clear flat glass (I use microscope slide glass). Clean it reall good (soap water, not just windex). Now apply a thin/ normal coat of cheap thermal paste to the bottem of your cpu heatsink. place it flat on the glass and look at the bottem. It will be fairly easy to see if you need to lap as there will be areas with more paste than others.

This is just anther option for telling how flat you got it. I use slide glass so I know it's flat. This should be easy to get at any collage in the area's school store.

Also for pressure. No more than the weight of your hand and the block. If you think it's enough pressure it's to much pressure.

I would show you mine but... well my current lapped heatsink is in use and keeping my cpu from melting as I type this.
 
DSC00699.jpg

---- was pretty bad, thats about 2 hours of sanding, barely touching the inside of the block
DSC00702.jpg

maybe 5 hours :|
99% of the time was spent on 220grit trying to get it flat
 
Ok guys I did my second attempt today, today I actually got some results but still not finished.

I lapped the CPU in a circular motion and it helped to make it flatter, but after 3 hours I gave up for today. My hands are hurting lol!

It is not completely flat but its getting there. I can still see the curve on the IHS, but I did my best using the 220grit for this session.

I am going to need a bigger sandpaper now, the comment about the pieces being to small was right, especially for the heatsink. So tommorow I will go look for some bigger 220 and 400 grits.

I couldnt do much with the heatsink this time because the sandpaper was to small.

I hope to be totally finished lapping this week. But I have gotten a good experience and good idea for what else to do.

I got roughly a 3-4c drop on Core 2,3,4 and 1-2c on core 1.
Will have to check the load temps.
 
Kr1z said:
Ok guys I did my second attempt today, today I actually got some results but still not finished.

I lapped the CPU in a circular motion and it helped to make it flatter, but after 3 hours I gave up for today. My hands are hurting lol!

It is not completely flat but its getting there. I can still see the curve on the IHS, but I did my best using the 220grit for this session.

I am going to need a bigger sandpaper now, the comment about the pieces being to small was right, especially for the heatsink. So tommorow I will go look for some bigger 220 and 400 grits.

I couldnt do much with the heatsink this time because the sandpaper was to small.

I hope to be totally finished lapping this week. But I have gotten a good experience and good idea for what else to do.

I got roughly a 3-4c drop on Core 2,3,4 and 1-2c on core 1.
Will have to check the load temps.
Click to expand...

thats pretty good, you'd get more if you went higher grit though, I used the marker to figure out exactly how flat it was when the marker would all disspear evenly it was pretty flat, I went a bit further then went up, I found that unless you have unlimited time, keep going with 220 until shes flat :) back and forth worked for me
 
Came back from some shopping :D

kcihjq.jpg


Some 9x11 220, and 440 grit sandpaper.
12x16 Glass 3/32'' thickness, it was the thickest they had at home depot
is this good enough? Also picked up a leveler, would this be better than the razorblade method?
 
3 hours! omg!

i cant see why it would take that long. I spent maybe 1 hour total, going from 220 to 1000.

This isn't rocket science, and the effect from lapping is a minor decrease. Not Like 20 degrees or something.

and sorry to say, that leveler you bought wont help at all. its too big, and will just ride over an imperfections. But no worries. go easy, dont get all freaked out about this; keep it simple and straight forward.
 
New Idle temps are
42-39-38-38

New Load temps are
70-70-62-62

3.4GHZ 1.31Vcore NB 1.450
425x8
Ram @ 850

Prime 95 25.5
30 minutes small ffts

Did another lapping session yesterday got a small 1-2c from stock settings.
Don't think I can do any more lapping I got it as flat as I possibly could of.
70 load on the first two cores :/
Also placed a fan on top on the video card blowing on the Tuniq.
Yea I figured that leveler didn't work lol, I jused a glass to measure the flatness and shined a flashlight through it.

I was expecting more on my setup and the cooling, but I guess I got a crappy chip :/
 
Kr1z said:
I dont think that can happen :O

How much force should I apply when I use the 220 and 400 grit?
Do I have to wet it or just lap it dry?
Click to expand...

When you lap, just let the weight of the HSF provide the pressure, all you need to do is move it. Try to equalize that pressure when doing your CPU
 
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