Hey im not a knife maker by any means but i enjoy messing around with sharpening and i love knives. I recently took one of my old skate blades and put an edge on it and it is surprisingly razor sharp, basically my question is how do i harden it? Is the blade already hardened? Any info would be great, thanks.
Well, I think the answer to this will depend entirely on what the blade is made from. I thought I read somewhere once that some high quality skate blades were 440 stainless but I don't know if that's all skates. I would suspect some type of stainless steel though. Once we know that, one of the guys who works with stainless will need to answer. I don't really work with anything but high carbon and tool steel.
The skate blade is probably hardened already, but you could check how a file cuts it vs a piece of mild steel. That would give a good idea if it is hardened, though it might be chrome plated and you wouldn't be able to cut the chrome with a file. I wouldn't try to re-harden it if you don't have significant experience already. Chrome plating can be toxic if heated too high and getting a proper heat treat is nearly impossible if you don't know the alloy. FYI, sharpness isn't a measure of hardness. Aluminum can be made shaving-sharp (and I've heard of aluminum skate blades as well).
I think most skate blades are stainless nowadays. I checked through ours. Modern CCM and Bauer ice hockey skates have stainless blades. Some of the old tube and blade types may be electroplated carbon steel. With these the ground edges would rust. I have heard also that skate manufacturers use 440 series steel, but without confirmation it's only a guess. Assuming they are 440, annealing and heat treating will be a chore. Best to grind them as-is. Be mindful not to cook the edge and kill the temper. I did a test on my cheapo Bauer hockey skates. My RC55 hardness testing file bit pretty good and didn't "skate" so well. Hahaha. Years ago I was able to sharpen a piece of 1018 mild steel to a near razor edge. It would slice like crazy, but one good hack into a 2x4 was all it took to roll the edge. It was a fun exercise.
I have it mostly ground down to an edge now, havent done final shaping but the edge seems to be very hard, a brand new nicholson file skates right off of it. Thanks for the replies much appreciated
We have a couple of skate blades at the shop, we dug around and found the one of the more common steels used is 12c27, same stuff used in stainless Opinels.
