| Electronics > Mechanical & Automation Engineering |
| Very High Grit Sandpaper Application Question |
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| shapirus:
--- Quote from: mzzj on January 03, 2025, 08:08:01 am ---3M lapping films are available to 0.05 microns that translates to about 500 000 grit. This would be wayyy beyond what is considered mirror polished. --- End quote --- Wow. I wonder what the application would be. UV optics? |
| jpanhalt:
As mentioned, I used them to make electrodes from glassy carbon for an HPLC detector. They worked very well. I believe the smoothness may have decreased absorption in the detector. The main advantage by far was that glassy carbon allowed virtually any solvent to be used as compared to graphite paste that was used before. I did not go to 0.05 micron as I recall, but the grit I used was finer than DuPont color sand paper. |
| Kleinstein:
Very fine sanding / polishing is wanted for metalograpic smaples. This can be optical, AFM and SEM. Usually the fine part it done with pastes, but a paper can be faster. |
| mikerj:
--- Quote from: jpanhalt on January 01, 2025, 01:16:27 am ---320 for headlights? I would start at 1500. If that doesn't work get coarser until it does. You will need to finish higher than 1500 unless you have power polishing. There's a difference between shine and scratch free optics. For example, electropolishing can give a high shine on a relatively rough surface. When you get to the end, a power buffer gently applied will be appreciated. --- End quote --- It depends on if you have to remove the remnants of the original anti-scratch coating or not. It can craze badly and get patchy on old headlamps, and you'll be there for days trying to remove it with fine grit. The finish doesn't last long if you have to do this though, even with a UV protector, as polycarbonate is so soft. |
| jpanhalt:
That's precisely why you start with fine and get coarser, at least for someone who doesn't do the job everyday. Once it's hit with coarse grit, you are committed. As for crazing, my only experience is with acrylic windshields. In that instance, it was due to a combination of stress, wrong sealant (mineral oil-based is bad), cleaning with organic solvent based cleaners, and exposure to sunlight. It was not not a coating and was not removed appreciably by polishing. A picture at the outset would have helped. |
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