The biggest challenge for most folks with rehabilitating an American scythe is getting the old, battered edge back in good shape. Wet grinders are the ideal, but they're not a trifling investment, angle grinders almost always burn the edge and destroy the temper, and many old blades have steel too hard for a file to effectively bite. While I would advise against using any old off-the-shelf grinding point for this sort of work, I was able to track down a source of A3 pattern grinding points that are specifically designed to cut cool on thin sections of hard, heat treated steel to prevent burning the edge when taken as thin as they ought to be (only about 7-9° per side.) They're more expensive than usual grinding points but are dirt cheap compared to wet grinders and chuck up in any old electric drill. At about the same cost as a file these make a great alternative for folks looking for a cost-effective solution for getting an old blade back in action. It was able to get this old laminated Emerson & Stevens blade in good order in a matter of minutes.
The first time you set the bevels on a blade are always the most labor intensive, but as long as you look after your blade after that it shouldn't take more than a quick couple of passes on both sides of the blade to re-thin your bevels as part of general maintenance, and because of how wear resistant American blades are you generally only need to rebevel the blade 1-3 times per season.
Nice! I've done a couple with an angle grinder, and I'll back you up- it's a real challenge to avoid burning things. Wrong tool for the job.
These grinding points look like just the ticket. They probably are designed to go in a pneumatic die grinder, right?
posted 3 years ago
Yeah the huge issue with angle grinders is that the discs are almost always made for grinding mild steel, which isn't able to be meaningfully hardened and so overheating it isn't an issue. As such the durability of the abrasive is usually prioritized and that means that you have the grit dulling down and rubbing, which generates heat, instead of shedding to expose fresh grit. Flap discs aren't as bad in that regard but are still prone to lots of rubbing-induced heat generation and they're too flexible so they convex your edge and round it over instead of keeping it thin.
These would work in a die grinder, large flex shaft tools (1/4" shank on it) or drills.