Randy -
Absolutely no slight taken on the reamer. I was poking at the concept of "gee, I made one of those years ago to do that, but never really thought about what to call it." In other words, you were making and using reamers but not really thinking of them as reamers since you were *only* deburring with them. That's probably what I love most about making (and fixing) things. You have to figure out what you want to do and then make it happen some how.
The "harden it, temper it" thing was definitely tongue-in-cheek. I figured that someone would pipe up about how dumb I am for even trying it, but it turns out that blacksmith books are full of things just like that. If the tool really matters, you can get all sorts of technical with temperatures, soak times, and quenching baths. But for home shop use, the seat of your pants will take you a lot farther than you might imagine.
About a month ago I helped my son change a Welch plug on the front of an engine (in a van, no less). We tried the poke and pry method, but it would not budge since we didn't really have a lot of room for the pry part. I walked out to my shop and cut a short piece of drill rod, ground the end into a sharp but tapered vee (like the simple reamer but with two faces), quickly hardened and tempered it in a propane flame, and the tip broke on the first whack. I reground it, tempered it a little hotter, and proceeded to use it to easily lift the edge of the plug away from the block until it caved in. About five minutes each of toolmaking and plug caving. The point of all of this is that sometimes you just have to stop and think about what would work, then go make it. Well, and to remind myself that antifreeze does more than control freezing (which we don't have too much problem with here in Florida).
In your case, you got the harden part right, but forgot to temper. Since I discovered the toaster oven I only try to temper in a flame if it is a real quickie one-off tool like the punch above. For 1/2" and smaller drill rod, the toaster oven set on broil will eventually get the part to 450 degrees or so. Slow is good anyway, so you can watch it happen and quench when it is "just right." You can easily watch the colors on a bright surface, so I usually harden, then sharpen, then temper, then sharpen again if needed. If the cutting edge is too small to see, I use 800 (or so) grit paper to remove the scale and bring back a bright patch before tempering.
I usually aim for medium straw color, which will give a tool a decent balance beween hard and durable. If it is a hard-to-make tool, like the reamer, I will go a little hotter, into a light bronze. That will cost a little more hardness, but help insure that the tool doesn't break or chip too easily. Decent tool steel gets darned hard anyway, so you have a lot of room for error.
Try it! Grab a piece of drill rod (it really is pretty cheap; flip to the back of the Enco flyer and add some to your next Atrax endmill order) or carbon steel and harden it (just like you did before; red hot and quench). Test it with a file to make sure it is hard. Now sand or stone or buff it to bring a shine back to it, and slowly heat it and watch the colors. Even with a flame it won't take much practice to get it a light straw color (at the cutting edge) before you quench it again. If you get it anywhere close to straw color, a file still won't cut it. But now you can pry or beat on it and it will take it.
The Complete Modern Blacksmith is a pretty good book, and contains a short chapter on hardening.
Don't forget to post pictures of your work!
Regards,
- Just Gary