Hi Will,
Here is the approach and tools I find most expedient:
1. I gather a Small piece of emery cloth, flat diamond file (coarse), and then a large black or dark blue sharpie pen.
2. With the engine running on idle...I "ink" the back of the blade. This is the "tell marks" often used by Smiths when shaping blades.
3. With the blade now turning just fast enough to engage the diamond file to "cut in," I do so into the top edge of the blade. I oscillate the diamond file on the top edge first from a 15 degree angle down to a 45 degree angle until a rough 45 degree profile is achieved on the top edge of the blade.
4. Repeat all steps thus far on the bottom edge...
5. With a rough "V" chamfer on the back of the blade...(note: this can be shaped in spots!!)...I now round over the "V" chamfer into a rough "bull nose" or "rondel" profile.
6. Smooth with the emery cloth.
The above are the basic stages of approach, and the tools. The dynamics of attempting this will teach better than my words. I thought I had this in a syllabus someplace, yet can find it. Feel free to cut, past, and edit at your leisure this post for the class if that has benefit.
Regards,
j
