It's really hard and I've no place to take the temper out. My mom wouldn't be too thrilled if I used her oven (if that is even an option).
Sure it's an option and won't hurt the oven in any way. I temper files in the kitchen oven all the time. Just make sure the file is clean. (If it had oil or something on it, then yeah it would stink/smoke up the place.) Since you mention tempering it back, it sounds like you're aware the file is already hardened, just a bit too hard and brittle for a knife. You're definitely on the right track. :thumbup:
First, use good quality files! Not cheapo Chinese or Indian case-hardened ones. I've used several Nicholson brand files; they are good solid steel (W1 or 1095, depending on who you ask) all the way through.
Here's how I do it: grind most of the teeth off one flat of the file. It doesn't have to be perfect, just so you can see the clean shiny steel. Preheat your oven while doing this. You're looking for a temperature between 450F-500F, but kitchen ovens are notoriously innaccurate, so start on the low side, say 375F. Of course if you're smarter than me you'll just get a good oven thermometer and check it.
Pop the file in the oven and let it "bake" for an hour. Pull it out (careful it's hot!) and let it cool down somewhere safe. It doesn't need to be quenched or anything, cooling in air is fine.
Now look at the bright shiny part you ground, and note the
color. This is just a thin layer of oxidation which will be easily ground/sanded off later, but it gives you a clue as to the temperature your oven was really at. You want to see a straw/bronze color. If it's real pale yellow, bump up the temp in the oven by 25 degrees. Sand off the oxidized layer before tempering again so you'll be able to re-check the color. If it's very brown, red or getting to violet, it got too hot; it may still make an OK knife but won't hold an edge very well.
That's basically it. Once I have the temp range figured out, I like to temper for an hour, let it cool and repeat. Twice is likely enough. It will now be a lot easier to work with an will take and hold a nice edge. I like file knives a lot and feel pretty strongly it's a great way to make your first knife. Some folks make file knives exclusively... not many, but some.
As to grinding bevels, just practice on scrap wood or metal. Some folks recommend paint-stirrer sticks to practice on. Don't try to get too close to the finished bevel with your bench or hand grinder; get close on the grinder and get closer by
draw-filing and filing. Then get the scratches out by
hand-sanding.
Note: all those links except the color chart came from the
Newbies sticky. *hint-hint*
Have fun!
