I am working on some high beds for my daughters (post when completed) that required some 3/8" mortise work. I thought I had a 3/8" chisel, turns out I don't. I tried to find an older bench chisel to match my "vintage" Stanleys, but none readily available on the web at this time. So I went to Lowe's to get a Stanley FatMax since they're cheap, forged and Sheffield steel. As I had the 3/8" one in my hand inspiration struck. I bought the 5/8" one instead for $10.
I took it home and blocked it in my drill press vise with shims below and on one side. I chucked up a mounted point on the drill press that I normally use on a die grinder.
After putting on my safety shield, dust mask and close fitting work gloves I spent the next hour taking tiny grinds off the edges of the chisel. The temperature never got high enough to worry about losing the temper.
I kept grinding keeping parallel to the factory edge of the bevel. When I got to .410" I took some measurements with a trusty micrometer and adjusted for .010" out of parallel. I worked both sides down to .374" and ended up only .002" off. I worked the rest off on a granite block with sharpening paper.
Here's the end product.
I have always balked at buying mortise chisels or registered chisels because I don't often need them. But now I might grind some more in 1/4", 5/16" and 9/16 as these are the mortises I tend to use with my mortising machine.
An inexpensive solution to a small problem I had.