I often damage my felling or limbing ax, warping the thin-bladed against knots or harder sections of wood. When this happens, I have to repair the blade to make it cut well once again. Here’s how I do it.
If it’s cold outside, I make sure to bring the ax into the house for a while before working on it. I don’t want to do the following with a blade made brittle by the cold.
Along with the blade needing repair, I gather a sledge hammer, a ball peen hammer, a metal file, a “puck” whetstone, and honing oil. I find make a comfortable place on the floor, lay out some newspaper, and begin:
Using the sledge hammer head as an anvil, I lay the warped blade on the sledge face, and beat the blade straight with the ball peen hammer. I do all of the blade work as symmetrically as I can, turning the blade over often to work on both sides. I beat the warps out of the blade, making it as true as possible.
Next, I take the file and shape the blade. I file in one direction only, so as not to damage the file. I try to make long, continuous passes in an arc, following the curve of the blade edge. I make a few passes, turn the blade over, and make another few passes, alternating sides. I repeat until the edge is a smooth arc.
I work slowly so as not to build up too much friction heat. This is why I don’t just use a grind stone—friction can “burn” the blade. Since I don’t know how much heat that takes, I’m careful to avoid letting it warm up noticeably.
Sprinkling the coarse side of the puck with a few drops of honing oil, I work along each side of the blade in a circular motion, reshaping the new edge until it’s sharp. When I’m satisfied, I oil the medium side of the puck, and finish the new blade. I try not to bear down on the stone, especially toward the end, letting the weight of it provide the pressure.
When I’m done, I give the blade a thin coat of gun oil, and it’s ready to go back to work.