Wow, it took me a long time to get this photo in from ShawPhotoshare. Not sure why it was so awkward... Anyway, Ive been working towards making some new knives this summer. Been a bit slammed with work, but have needed some new carving knives since my pal Mike from Preferred Edge passed away. I fooled around a bit with 5160 steel, but had to send away to Alabama Damascus Steel to get it in 1/8th", and the postage was too high for me, so I think I'll wait to use 5160 again until I get a forge and proper anvil. So these are O1 steel, medium sized bent blade and straight knife. Mike used to use L6 steel, which was dead tough, but I had some trouble with some of them keeping an edge, so I thought I'd try this steel. Mine are a bit more home-made looking, rather than the beautiful hand-crafted pieces I see on this forum, but I hope to get better with my grinding and finishing. I had some trouble with one blade from a batch of four smaller knives like these. The longest, thin blade bent while putting a final edge on it. I remember Mike saying that he used a pan of cat litter to temper in. He'd bring it up to temperature, than put the small blades in, so that they wouldn't overheat when the elements came on. Anyone else do that? is it worth trying?
For O1, you want to harden by bringing it up to critical (non-magnetic) and let it "soak" at that temperature for a bit to make sure as much of the carbon gets converted as possible(A minute or so for small blades is fine). The key is not to overheat the blade, or it won't harden properly. In a forge, you can work the blade in and out of the heat to maintain a consistent colour. Also, make sure the piece is really at non-magnetic when you do your quench. For the temper, I use a cheap toaster oven I got at Canadian Tire. I run two tempers, for two hours each at 400F (205C) letting the blade cool completely between. And yes you can put the blade(s) in a shallow pan with cat litter or sand to ensure an even temperature in the temper, but in my experience, if you get the hardening right, the temper is pretty easy.
Hm, not sure where I went wrong. I picked up a small paragon glass kiln to do the hardening cycle, so I think that part is okay, and quenched in warmed canola oil. I didn't want to admit that I use a cheap Canadian Tire toaster oven as I thought it might make me look even less professional, but if you use one too I feel a little better about it. I used three tempering cycles because I heard that helps to make a tougher blade. Maybe I picked up a piece of my 5160 by mistake, which tempers much lower. I'll be extra careful with everything next time, and I appreciate your advice. I added the photo again, as I'm not sure they went on properly last time.
If you're using an oven, it should work fine. You could check your oven temp, ether with a pyrometer, or simply heat a piece of O1 and pull it out when it gets up to temp to make sure it hits non-magnetic. Also, three tempers might be a bit much for O1. Perhaps you're drawing it back too much, especially if you want a harder blade. You probably have this, but here's some info right from the spec sheet for O1: Hardening [TABLE="class: grid, width: 500, align: left"] [TR] [TD]Preheat[/TD] [TD] Heat to 1200° F, and hold at this temperature until thoroughly soaked.[/TD] [/TR] [TR] [TD]Hardening[/TD] [TD]Heat to 1475 to 1500° F. Soak at heat for 30 minutes per inch of thickness.[/TD] [/TR] [TR] [TD]Quench[/TD] [TD]Oil quench to 150 to 200° F. Temper immediately.[/TD] [/TR] [TR] [TD]Temper[/TD] [TD]Normally oil hardening steels need to be single tempered only. However,double tempering may sometimes be preferred. Soak at heat for 2 hours per inch of thickness for each temper. Air cool to room temperature between tempers. The normal tempering range for this grade is 300 to 450° F.[/TD] [/TR] [/TABLE] As with all things in knife making, experimentation is key to quality. Changing the soak time, temperature or type of quenchant, reducing the number or temperature of tempers, all will make changes to the characteristics of the finished blade.
Thanks, ill double check everything, and start by tempering only twice. I was tempering at 450c, according to my thermometers. I'll experiment with that next, if things don't work out. Wow, being organized and methodical is requiring me to dredge up some maturity I usually do okay without...
