Hollowing the back of plane irons and chisels
Link Van Cleave
>Stimulated by the recent discussion in the plane iron thread about warp-age I wanted to share a method I use to handle difficult chisels or irons that need a lot of flattening or are convex instead of concave. A convex back it a pain to deal with not only because there is usually a lot of material to remove to get flat but it is difficult to keep from rocking when actually flattening. So what I do is to use a dremel or similar tool to create a sort of hollowed back. I don't go for enough hollow to create something like a Japanese tool but enough to lessen the amount of steel I remove and to keep the rocking problem at bay.
What I do is take some masking tape (I don't do this anymore but it is good to do at first ) and put a layer about 1/8" or so in from the front of the iron and 1/8" from the sides. This is to protect these areas from the grinding I will be doing. Then I take the Dremel with a small grinding wheel about 1/8" in thickness and start to make slightly overlapping passes front to back with light pressure. I go about 1/2 to 3/4 of the way up the iron. I then turn the iron 90� and make another series of passes just inside the first ones. Because of the change in direction you can see exactly where you are grinding by the way the grinding marks are 90� to the others. Turn 90� again and repeat. Each time you are getting closer to the center and making a hollow that is deepest in the center.
All this takes about 30 seconds. I hold everything in my hand. A lot of times I do it very quickly and go back to my flattening stone, take a few passes and take a look. I can see where I need to grind a bit more and how things are progressing. When I get to a point where it looks like I am close to having the back flat, not the whole back but the sides and front, I will start to do my final flattening and polishing. Buy the time I am finished there are usually only a couple of small traces of my grinding operation. These will be removed by the act of normal sharpening during the use of the tool. This is a very light process. I am not hogging out material, just lessening the amount of work I have to do and creating a non- rocking surface to flatten. I can flatten the backs of really messed up, i.e.. belt sanded flea market chisels and plane irons in no time. Saves a lot of hard work. Hope this is clear, much easier done than explained. This has really worked well for me.
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