The Adze is a tool which is swung about a pivot point when used, and has two key angles, α and β.
α is the effective angle at the cutting edge. The inside and outside edges will probably be cleaned up and polished; however this is the effective angle between those edges.
When resharpening, try to to not change the β angle
β is the angle between the handle and the cutting edge. As the adze is a tool which is swung about some pivot point, this angle has a great impact on the usability of the tool.
The angle needed for β is out of scope of the Sharpening Handbook, however, there are articles below which address how this can be determined, and how to set it.
|25° - 30°||25°||
I've seen recommendations for α as low as 20° however this could be too shallow unless the user is working on very soft woods..
Roughing out cuts
|25° - 35°||30°||Use a higher α especially when working on dry hard woods.|
When resharpening, it is best to only work on the inside part of the bevel. Modifications to the outside part of the bevel (the back bevel) could adjust the β angle, also known as the “hang” of the adze.
Having a bevel on the outside of the tool allows it to be better used for shallow scalloping work. The article by Dave Fisher in “Fine Woodworking” magazine shows this well.
To sharpen a lipped adze (also known as a shipwright's adze, and used for cutting across the grain), see the instructions in The Complete Guide to Sharpening by Leonard Lee. The recommended α angles follow those noted above; however the directions are a bit difficult to describe.
Note: Dave was not merely resharpening the tool; rather he had to do some fairly significant reshaping to the tool's cutting edge. If you do such do such modifications to a tool, be sure to manage the heat so that you don't lose the temper in the metal.