I found an old chisel in the basement that had obviously been used and sharpened many times. It was completely useless because it was not only blunt but also rounded and could not be aimed at the wood I was removing.
So I had the idea to grind it and take microscope pictures along the way. These were taken at 70x magnification and show the transition from coarse to superfine grinding stone and the gradual reduction of the grinding track of the large diamonds.
The most important lesson for me was to grind longer than I think before moving on to a finer grind (smaller diamonds), as it actually takes some time to remove the material that makes up the top of the grooves and reach the bottom of them where the smaller diamonds naturally create their own grooves.
The grinding times were approximately:
- 150 microns (100 Grit) - one hour! Note that I had to remove a lot of material to get a flat surface and meet the original edge
- 60 microns (300 Grit) - two minutes, but should have used five minutes and done the surface sanding already with this grit
- 30 micron (600 Grit) - one minute, but should have used five minutes and done a plane sanding
- 15 microns (1200 Grit) - 30 seconds, but again I should have used five and done more plane sanding
So what did I achieve and why should you bother watching the video? Below is the edge after making the transition from 100-12oo Grit
After this we of course need to polish more with leather and polishing paste, but it's a very good start and already really sharp. Anyway, below is a compressed film of the process, a little less than 3 minutes long. I hope you like it!
