Most of us are starting out with O1 Tool Steel, and it's a great choice. Some knifemakers stay with it for a long time as their steel of choice, as nothing holds an edge better and it's easy to work with and heat treat. BUT, there are a few things I've learned over the past 9 months. 1) Buy Precision Ground O1, or you will spend most your time getting all the boogers out. Even with PG steel finishing is the hardest thing. 2) The more finish work you do on the ricasso area before heat treat the better off you'll be. This is the area between the plunge cut and handle area. I thought that since this stuff was PG I didn't have to do much - wrong! I now finish this area to 400 grit, also going over the edges. The Blade itself can be left at 220 since your going to re-grind it - just don't leave any big scratches that can act as stress risers. 3) When heat treating, do not stick the non-magnetic (almost 1500 degrees) blade into cold quenching oil - warm it up to about 125° first. Just heat up a piece of metal and drop it in the oil if nothing else. The blade goes through massive stress when it's quenched, and if it is going to crack it'll do it now. I've been lucky as I've not had one break yet. 4) Normalizing - this is something that should be done before heat treat to make the process easier on the blade. Heat it up to near non-magnetic but not quite, then take it out and let it air-cool. 2 or 3 times doing this really helps the blade. 5) Differential heat treating - if you harden the whole blade you will have a good knife, but one that can break in half at the plunge cut. Using refractory cement along the spine during heat treat will not allow the metal under it to cool as rapidly, so you get a hard edge and softer spine. It makes a knife that will bend and not break, and all my knives get this treatment. You'll also get a cool temper line, and if you etch the knife it'll look really neat-o. 6) After heat treat, while the knife is still hot, I use a file to check the edge of the knife. It should bounce off and make a glassy sound, then it goes into the toaster oven that's already on and set to 400°. I keep it in there for one hour - some go longer and use different temps. You'll have to find what works best for you. Toaster ovens are under $20 at Wal-Mart. 7) Finishing. This is tough stuff for me, and something I have not yet begun to master. Tonight I ground a blade to 380 grit, then sanded by hand to discover I had lots of 50 grit scratches still there. This is the hardest thing to learn, after grinding. Take your time and think about using Scotchbrite belts - without them I don't know what I'd do!
One more - get your O1 HERE Great prices and precision ground - I've ordered every bit of mine through them and never had a problem.
