Quote:
Originally posted by gone_fishin
Makes me wonder, what ever happened to the "600 grit is fine enough" montra? Now the talk is in microns
|
600 grit 'IS' fine enough, since 99% of you do not have the means to measure flatness, therefore there is not a need to do a fine polish job.
I was stating that to use optical flatness measurement techniques with optic flats, the surface needs to be sufficiently reflective (polished.)
You can talk about lapping/polishing papers/pastes in grit or micron size.
Surface height deviation from true flatness can be talked about in (percentage of) wavelength of light, or in SAE or metric terms such as millionths of an inch or in microns, etc.
Be careful not to confuse the issues and measurements.
Heatsinks are still large enough that you can measure surface height deviation (flatness) mechanically with a good dial indicator (dial or digital) and a pair of accurate granite or steel block flats, down to 1 micron, but you have to know what you are doing.
CPU surfaces are NOT large enough to do this, and their flatness can really only be measured by optical means or with a profilometer, etc.