How do you know its tool steel? Is it marked? Many saw blades had the bodies left relatively soft compared to the teeth, which were hardened separately from the body. There is such a variety of tool steels that saying it is a tool steel without saying what type just lets everyone know that it will harden with proper heat treatment, which will vary from one steel to another. The only real way to harden what you have without spending any more money is to make some test strips and practice with your torch and try various tempering temperatures with the oven. Then when you feel confident in your ability to get what you want, harden your knife and temper at the best temperature you've found. With the gear you have, I'd say you want the test strips to get to the point that when you try to bend one, it bends just a tiny bit, then breaks. The break should look like fine grey velvet. If you practice a few times in a dark room, you can see the point that the steel changes from the room temperature structure (ferrite plus carbides of some type) to the structure that is ready for hardening (austenite, typically also with some carbides of some type, at least for knife steel). The steel will be a dull red and increase in brightness slowly, then will appear to dim before finally going to the final bright red color. Just as the brightness starts to increase again after dimming is when you want to quench. You dont list one in your gear, but if you can get a magnet it will help to judge the hardening temperature. When the blade is no longer attracted to the magnet, heat it a little more, then quench. You'll also need to try a couple of different quenches with your test strips. Some oil (motor oil, olive oil, canola oil), some water, and some icy salt water (ice brine). Oil may not harden the steel, and water may crack it. Beware that sticking a red hot piece of steel into any oil will cause a fire, just on the oil surface if nowhere else. After quenching, temper it in the oven. Set the temperature at 325-350 and work up from there. If the edge is brittle, increase by 25 degrees and try again. I suggest the brass rod test to determine if the edge is brittle, or try carving some hardwood. All the knives I've made that I heat treated were heated with a Mapp gas torch and quenched in olive oil or water. All of them warped or cracked, about half were salvagable, and out of about 10 blades, I got one that I was satisfied with. It was a 1095 kiridashi, took a scary edge, and when I tried to break the tip in a vice, the handle bent. This was without scales as I used a cord wrap handle. I suggest a lot of practice or a more surefire method.
