This is another ongoing tribute, in my life, to Piano Technology mentor Mr. David Betts and Ms. Debbie Cyr.
At the piano shop, the owner prefers DMT diamond stones. They are heavy and solid. I work with his set the best I can but found that the course stone looses its grit very quickly, and quickly it becomes close to "fine". Recommended by fine woodworker Mr. John Cameron located in Gloucester, MA, I bought a set of water stone. They work much better, not loosing grit. The stone brand and price vary greatly. So far, this set of Naniwa water stone from Sharpeningsupplies is working well.
For chisels, the bottom is flattened first using all stones from very course to very fine until a mirror like shine is at the tip/working area.
Next, the chisel is getting a hollow bevel at 25 degrees using Tormek or dry stone wheel. The second picture is a manual grinding wheel at John's shop, which is my favorite. You can adjust the speed, rotating direction, and stop when you need to. Notice the shine on the bottom of chisel.
After the hollowed bevel is created, it can be burnished on stones from very course to very fine or from 220 to 8000 grid. The grid choice is personal, one can choose what works best for the job. When burnishing on each grid, check if a bur is present after a few strokes. With a bur on the tip, remove it by rubbing the bottom of chisel on the finest stone. Then move on to a finer stone for the bevel until a finer bur is present, and remove the bur on the finest stone. The last picture shows the personal final result of sharpening, both bevel and bottom polished on the finest stone.
This is the shop owner's cutting tool on piano bridge notches. It was marked with magic marker to see how the sharpening process went. The tool was in rough shape at the beginning causing a total of 2 hours to have it shine. Of course, after years of practice, the sharpening time can be reduced significantly.
This bridge notching tool is made of a putty knife, edge rounded. Again both bottom and bevel were marked with magic marker to see the progress. The bottom was very chewed up, took about 1 hours to flatten. The two edges was polished by feel.
One whole day passed by to sharpen all tools needed for bridge notching, well worth the effort. By better tool maintenance, hopefully it won't take up this long before tools are sharp for the job. Thanks to my big boss Mr. Jude Reveley and woodworking mentor Mr. John Cameron. Keep practicing!