I have unreasonable sentimentality about Stanley Model 40 chisels. I started buying them about 30 years ago just as they were being discontinued. They seem to sharpen easily and hold a good edge. I was always missing the one inch chisel and recently was lucky enough to find one on eBay.
Step 1: Beat up chisel handle
When I received it, I noticed that the back of the handle had been hit pretty hard over the years.
Step 2: Badly sharpened bevel
When you saw the bevel, it was no surprise that someone had hit it that hard. It looks like it had been sharpened multiple times but each sharpening had only added another facet to the bevel.
All chisels, whether new from the factory or used, need tuning before they work well.
Step 3: Reason #1 for sharpening
The primary reason to sharpen a chisel is shown in this photograph. You can see how poorly the chisel cut a piece of softwood and all I was trying to do was pare a small piece off the corner. The chisel crushes the fibers until they break rather than cutting them.
Step 4: Reason #2 for sharpening
And there’s a second less obvious reason. For 35 years, I have carried a reminder on my left palm of the dangers of working with a dull chisel.
Step 5: The back of the chisel
Ideally, you want to have two perfectly smooth surfaces, the bevel and the back, meet to form the cutting edge. Any imperfections in either will reduce the sharpness of the chisel.
Here’s the chisel back when I received it. You can still see the machine grinding marks left from the factory.