I finally sharpened my mortising chisel, I had been waiting for a package from the Japan Woodworker (in retrospect I shouldn't have expected fast delivery from a company on the other side of the country). I bought a DMT 335 8" x 3" diamond stone, and a honing guide. I know that the honing guide might be controversial, but for sharpening, there are two options: buy a honing guide, or use a grinder for a hollow grind. I have a grinder. It is noisy. It is messy. Now I have a honing guide.
The diamond stone, I don't think is so controversial, it works great, and is very reasonably priced. I use it for truing up waterstones, and for grinding a primary bevel. Here is a group photo of my sharpening arsenal:
The water bottle is very important, it speeds up sharpening by a lot. I play trombone, so I have this bottle floating around. Someday I'll upgrade my bevel gauges, something better than balsa wood would be nice. I also made a jig for repeatable settings on the honing guide, I post that in a later post.
This all brings me to the project at hand; the mortising chisel. I first lapped the back, then worked on the bevel. The bevel was tricky, it was chipped, and had a curved bevel, the opposite of a hollow grind. using stones would be too slow, so I switched to my grinder. I ground the bevel until there was about a 1/16 flat area at the tip, since I have a 4" wheel I didn't want to make too weak of an edge. At this point, I discovered that I have a laid-steel blade, which is a blade that consists of two steels. The harder one is at the bottom, and the softer one is at the top. This is not common in modern western-style tools, but this technique is still used in many Japanese edge tools. The rest of the bevel was then ground at 35 degrees.