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RoboTech · 02-11-2003, 11:41 AM

Very intersting thread, with lots of good info...

I, like many, hand lap my waterblock and heatsink bases with the hope of improving heat transfer thru better surface area contact. I use plate glass, wet/dry paper and linear motions and try to keep things as clean and consistent as possible. I realized some time ago that Flatness was my goal and not a pretty surface finish. I usually stop at 1200 grit and rely of the "vissibility" of high and low spots to judge flatness. When I can no longer see high/low spots then I have gone as far as my limited tech will take me. Thru comparative testing, I can regularly see a repeatable improvement in temps - from pre-lap (not flat) to post-lap (as flat as I can get it) so I know I am doing some good. I hold the impression that the effort involved with lapping produces diminishing returns - the closer you get to Flat, the less change in thermal transfer that will occur.

I don't have an optical flat and can't justify the cost in buying one to support my hobby and curriosity...

(Maybe someday)

So what is the average enthusiast to do??? For those of you who do have the equipment and experience to know FLAT and be able to measure it, are we basement lappers just kidding ourselves (in my case I think not - because I can measure (with some degree of repeatability) an improvement in temps)? Can someone give us some rough guidelines for what typical flatness would be for a fine machined finish, hand lapped surface, or professionally flattened surface???

And I would love to know how FLAT the top of the CPU core is...

I assume they are pretty flat, but what does a typical XP core or P4 heatspreader look like under an optical flat??? Anyone have pics?

02-11-2003, 11:41 AM	#19
RoboTech Cooling Savant Join Date: Sep 2002 Location: Cincinnati, OH Posts: 229	Very intersting thread, with lots of good info... I, like many, hand lap my waterblock and heatsink bases with the hope of improving heat transfer thru better surface area contact. I use plate glass, wet/dry paper and linear motions and try to keep things as clean and consistent as possible. I realized some time ago that Flatness was my goal and not a pretty surface finish. I usually stop at 1200 grit and rely of the "vissibility" of high and low spots to judge flatness. When I can no longer see high/low spots then I have gone as far as my limited tech will take me. Thru comparative testing, I can regularly see a repeatable improvement in temps - from pre-lap (not flat) to post-lap (as flat as I can get it) so I know I am doing some good. I hold the impression that the effort involved with lapping produces diminishing returns - the closer you get to Flat, the less change in thermal transfer that will occur. I don't have an optical flat and can't justify the cost in buying one to support my hobby and curriosity... (Maybe someday) So what is the average enthusiast to do??? For those of you who do have the equipment and experience to know FLAT and be able to measure it, are we basement lappers just kidding ourselves (in my case I think not - because I can measure (with some degree of repeatability) an improvement in temps)? Can someone give us some rough guidelines for what typical flatness would be for a fine machined finish, hand lapped surface, or professionally flattened surface??? And I would love to know how FLAT the top of the CPU core is... I assume they are pretty flat, but what does a typical XP core or P4 heatspreader look like under an optical flat??? Anyone have pics?