Lapping?

known12345

Junior Member
Dec 23, 2007
16
0
0
Was wondering, where exactly do you find high grit sandpaper and glass? The homedepot close to my place sells grit of only 600, is this sufficient, or do I need a higher grit to sand my cpu and heatsink? Also, where exactly do you find glass and how much does it cost? I have not yet gone to home depot so not sure if they sell glass but when I checked their website, they do not appear to sell individual pieces of glass?
 

myocardia

Diamond Member
Jun 21, 2003
9,291
30
91
You can buy 8 inch by 10 inch pieces of glass at WalMart or any dollar store for about $5. They keep them in the photo frame section, and you even get to pick out the color you want your glass holder to be. And to get high grit sandpaper, any auto parts store will do. The AutoZone that's closest to my house carries grits up to either 1,000 or 1,500.
 

Pyrokinetic

Senior member
Dec 4, 2005
296
0
0
myocardia is correct, I also got mine from an auto supply store -- wet/dry sandpaper in painting and finishing supplies. I started with 400 grit, and worked up to a 1200 grit (400, 600, 800, 1000, and then 1200).
 

BonzaiDuck

Lifer
Jun 30, 2004
16,122
1,738
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With all due respect to the other respondents here, I won't take the time to read their posts.

The harder the metal, the lower the grit needed for a mirror finish.

For heatsink bases and IHS processor caps, you neither need -- nor want -- a mirror finish.

Some coolers come with nickel-plating on the heatsink base, and your first objective is to remove the nickel-plating while making the base absolutely flat. The second objective is to remove the deepest scratches -- perhaps to something like a "satin-finish" with minor scratches or swirls.

You want to remove the nickel-plating because nickel has a higher thermal resistance and lower thermal conductivity than copper. This is a very significant reason why lapping improves cooling, even if it is not the exclusive reason. The flatness of the mating surfaces contributes to the remainder of the improvement, and this factor is not insignificant either.

To do this, use wet-or-dri 220-grit or 320-grit to grind off the nickel plate. As you use the sandpaper, the grit will become "subdued" or worn. This in turn reduces the scratching, but increases the number of passes necessary to "achieve objectives."

Once the nickel-plate on either the heatsink base or processor cap is worn down with the exception of a few thin patches, move up to 400-grit. The 400-grit will then also lose some of its grit, and by the time you've polished the metal a tad more, will leave minor swirls.

To keep the sandpaper from clogging, just run cold water over the sandpaper under the faucet so that it's wet. When it starts to clog up with gray-metal or red-metal particulate, take a break and rinse it under the faucet, shake it off, and then resume.

For a glass surface, find a countertop, a glass buffet or coffee table surface. We used to buy plate glass to cover fine wood furniture. If you don't have something like that, you should be able to buy yourself a 12"-square piece of glass with little trouble.

For the choice of sandpaper grit, I've used 600-grit, but it's really a total waste of time given my explanations above. Anything finer than that -- 1,000 grit, 2,000 grit -- is also a waste of time. A white paper on lapping notes that you really want some microscopic scratches on the metal surfaces, so that the micron-sized particulates in the thermal paste -- preferably silver (second-best) or diamond (first choice) will make something like "3D" contact with the metal surfaces. A highly polished surface, on the other hand, won't trap these particulates and the pressure resulting from the mated surfaces tends to squish all the thermal paste out the edges of the two surfaces.
 
Dec 30, 2004
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My TR-Ultra-120 and processor did not benefit 1C from lapping both, solidy and to a nice finish that was nearly mirror. Lapping is overrated in my opinion. Still was fun though, and I might do it again, because trying to get better temps is fun
 

Gustavus

Golden Member
Oct 9, 1999
1,840
0
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All ACE hardware stores have wet/dry 1500 grit sandpaper -- made in Finland. It is $1.69 per sheet and while it does not produce a "mirror" finish on copper, it does finish copper to a very smooth surface when wet lapped.
 
Dec 30, 2004
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Originally posted by: Aflac
Originally posted by: soccerballtux
Got some 2000 from an autozone nearby. Pick up some Brasso as well; that'll perfect the mirror finish.

Brasso is a bad idea.

Hm, but I beg to differ; I agree with the guy who talked about the site/review someone made comparing mirror to non-mirror finish, and finding the mirror helped even more.

That topic really doesn't discuss much of anything, some dude talks about residue leftover but that's what we have rubbing alcohol for.

I still hold my position that if you want to lap, go the whole way.

But I don't think it's necessary to lap.
 

BonzaiDuck

Lifer
Jun 30, 2004
16,122
1,738
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Originally posted by: soccerballtux
My TR-Ultra-120 and processor did not benefit 1C from lapping both, solidy and to a nice finish that was nearly mirror. Lapping is overrated in my opinion. Still was fun though, and I might do it again, because trying to get better temps is fun

Well, soccerballtux, I appreciate your input here.

Even so, let me observe this. First, in the best tradition of scientific tradition beginning with Bacon, Descartes, and the 17th-century contribution to the "history of ideas," there is a difference between "Knowing," "suspecting," "believing that you know," and [God forbid] -- "believing."

Let me summarize my "method."

1) I ran Coretemp while testing stability and temperatures after taking each successive approach to cooling.

2) I turned Coretemp's logging feature "on," setting it to sample at 8-second intervals and log at 8-second intervals.

3) I carefully controlled room-ambient, using a digital thermometer that I had also calibrated with a bowl of ice and ice-water for an hour.

Here are my results:

1) Switching from TR-Ultra-120-[original] to TR-Ultra-120-Extreme: an improvement in load temperatures, same room-ambient, same over-clock setting, of -5C degrees to -8C degrees. The range of difference there was a comparison of my results with review results, and the difference between lapping the U-120-Ext and installing it without lapping.

2) Diamond thermal paste: measured improvement, at same over-clock setting as (1), shows an improvement between -2C and -4C degrees, same room ambient, same over-clock setting.

3) Lapping the processor cap to bare copper: Tested on a Q6600, an E2140 and an E2180 respectively, a -4C to -5C improvement in load temperatures at same and/or normalized room ambients -- across the board.

Room ambient is very important in being able to see and measure these changes. From my experience, still following "the method," I observed -- and others have probably observed -- that changes to room-ambient affect all component temperatures linearly, and degree-for-degree. Thus a 1-degree increase in room-ambient means a 1-degree increase in load-temperature -- with absolute certainty. The only way this relationship becomes "an approximation," or varies slightly in accuracy, arises from the operational ranges of certain heatpipe coolers. Those coolers may be more effective, for example, at room-ambients of 55F and above. But any loss in effectiveness at lower room-ambients is completely obscured because the cooler doesn't need to be quite as effective at those lower temperatures.

In any case, we measure the impact of these incremental cooling refinements in a range between 68F and 80F. In the event our room-ambient is lower by some few degrees than this range, the linear relationships still remain overwhelmingly effective, so normalizing the results under these assumptions produces pretty accurate extrapolations of load values at higher room ambients.
 

BonzaiDuck

Lifer
Jun 30, 2004
16,122
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A Footnote:

Many will notice with quad-core processors that PRIME95 for probably more than one test (sFFT's versus Blend versus large FFTs), shows discrepancies or lags on some cores compared to others between, say, 270000 Lucas-Lehmer iterations of M_____ using FFT length 20K, and 9000 Lucas-Lehmer iterations of M_______ using FFT length 448K. For want of a better answer, you have four cores competing for use of the same memory, shared L2 cache between each pair of cores, and an operating system performing some minor activities in background even with all system tray programs turned off.

Therefore, you will see spikes in temperature samples that shouldn't "be there," as one core finishes up a particularly stressful test, while the others begin a less stressful set of iterations.

For this and other reasons, it is important to get samples of data for an hour or longer, for intervals even as frequent as 8 seconds. Further, you should use the sample to get spreadsheet calculations of average core temperature, average temperature per core, standard deviation by core, and overall standard deviation. The manipulation of data also gives you the load temperature range by core and a load temperature average range for all cores.

So while you may actually see occasional spikes that don't seem to deviate much from "control test" results (without a particular cooling enhancement), a comparison of averages and standard errors will reveal much -- provided the test and the control data set are taken with the same configuration, same over-clock, same room-ambient, same PRIME95 stress-test, etc.
 

BonzaiDuck

Lifer
Jun 30, 2004
16,122
1,738
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The issue about "mirror versus unmirrored" may have exceptions if the particulate matter, most notably synthetic micronized diamond, is an industrial-strength abrasive. The particles will not move around much under pressure using mirrored surfaces. In fact, if they are spread so that a couple layers of them are "piled up," putting them under pressure may even out the multiple layers, but they won't move around much beyond that.

I'd really like to see the day when they can simply replace heatsink bases and processor caps by some sort of "molded diamond" composite that doesn't show brittleness while displaying the strength of the metal items.

Maybe it's possible; maybe it isn't. If it's possible, then the cost is probably prohibitive, and we're stuck with copper and diamond paste.
 
Dec 30, 2004
12,553
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from lapping their cpu.

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Phunk0ne

Senior member
Jul 20, 2007
494
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and I am not the only one that has benefited from lapping my heatsink and IHS

But for some it works and for some it doesn't. Lapping IHS and or heatsink when you are not overclocking might be a waste of time and warranty.

edit: finished it off with brasso.

Just so I can show it off, again
 

BonzaiDuck

Lifer
Jun 30, 2004
16,122
1,738
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I got 400 grit
an' a little spit.
Took my bran' new chip
from its anti-stat slip.

Gonna grind it down
for lowes' temps in town.

For thermal paste
Burma Shave's a waste.

But I'm not fooling
When I say "Innovation Cooling. . . . "

* * * *
Humor aside -- If you measure it carefully, and it works for you, who cares what anyone else thinks?

ALSO, PHUNKONE IS RIGHT ON. With these C2D and C2Q processors, and the new Penryns, if you do NOT plan to over-clock, this is all an anal-retentive waste of time, money and energy.

But those of us probing the FSB and VCORE ladders, we're happy with it.
 
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