How do you support your blades in the oven?

L6steel

L6steel

Joined
Sep 23, 1999
Messages
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I'm fixing to heat treat a big bowie. I took two fire brick and cut a slot down the middle of em on my table saw, just wide enough for the blade to sit in. This way the blade will be standing edge up in the fire brick and supported full length except for the last couple inches of the tang. Is this ok as long as I leave the blade in the oven at critical temps long enough that it soaks good?
In other words, is there any chance the fire brick would insulate the blade and not let it get as hot as it should?
I thought about just laying it down on top of the brick but then it looks like one side would get hotter than the other and you'd get warpage.
I appreciate any help you can give me!!!
Can't wait to smell that olive oil when the hot steel hits it! :)
 
i use a soda can cut in half and then put a notch on each side so the blade has a place to sit, so it looks like a little aluminum bowl with a notch on each side. so far so good.
 
Michael, I was doing it your way and never had a problem. When I mentioned it to Tim Zowada once, he told me that the brick could act as a heat sink and that I should switch to steel. He was using a 1/2 longitudinal section of pipe as I recall, with slots cut in the pipe. I went with channel steel because is was available and then had a friend mill some slots in the channel sides. I suppose a chop saw would work well too. I had neither. I use either one or two, 6" x 4" x 2" sections in my 18" oven, depending on the size of the blade.

ETA: Terry, I hope you are joking. Aluminum melts at 1221 F, way below the heats necessary for knife makers. Granted, in the can it is alloyed, which will change the melting point, but it seems awful risky.
 
Terry the melting point for Aluminum is 1220°F, give or take a degree or so. How can it hold blades in a furnace?
 
I have a piece of 1" aluminum square tubing that I cut slots in. Tempering oven only.
 
Awwwwwww shoootttt! :(
So the fire brick idea is kaput!
Hmm, I'll have to dig around in the shop and find some metal to use. The buggers gonna be cutting the slots in it.
Thanks guys!!!!

Terry, thanks for the handy tip for a tempering holder!! I think something throw away like that is great. Use one and then pitch it. Help keep the blades clean.
 
maybe you could get a stainless steel measuring cup from the dollar tree and cut a couple slits in it to hold it up, it should be about the same principal right?
 
I have a shallow groove in my firebrick so the blade almost leans against it. I figure if I am edge quenching anyways, I am not worried about the spine being a bit insulated. Tell me if this is a bad idea.

Otherwise, i will have the same slot in my brick with a nail coming through the bottom of the brick so the tip of the nail pushes the spine high enough to not have it insulated. Im not worried about insulating the tang, so it could sit rather deeply into the firebrick at an angle.
 
I took a piece of scrap ss from a restaurant kitchen top. bent the back end and sides up to sheild from direct coil heat, drilled several 1/8" holes 1/4" or so apart and put 1/8" steel rods in them. I can place several blades in the oven at once on edge for normalizing, annealing and quenching. I used a ss pipe but I could only get 2 blades in it at a time and I like to heat treat 4 or 5 at once, helps cut down on waiting times and expense for the oven to heat up.

Bill
 
Well, mister impatient here went ahead and used the fire brick holders to heat treat this bowie. I set it in the groove and 3/4's of the grind was above the brick, plus the groove was wide enough that I didn't think the heat would have any problems getting at the blade. When I took it out of the oven it was a nice even red all over. Stuck it in the olive oil and found out I need three or four more cans of it, lol. I've already bought nine three quart cans of the stuff. Only part stickin out was the last inch or so of the tang. Once I pulled the blade out of the oil it smelled like a pizzaria in my shop. Ummmm ummm ummmmm!!! :)
I cleaned off as much of the gunk as I could in my dip bucket. I remembered someone said dish washing liquid was good for removing the PBC after heat treat. I know you're supposed to use hot water but I don't have a way to heat it in the shop. I was real suprised how the blade looked once I got it cleaned. Never seen a hardened blade that hadn't been tempered before. It looked like it had been galvanized. Do they all come out like that?
I got a little edge warpage but nothing I can't remove after it's tempered. I was so happy when I tapped the tip on a piece of marble and heard a nice solid ringing sound. No cracks, whew!!!
I'm takin this one to TrackRock with me so me and Mark can do some cutting competetion so I'll get to see how my heat treat came out.
Can't wait to get at those 2 by 4's and free standing water bottles!!! :D
Oh yeah, I brought it up to 600 and held it for 15 minutes, then put the PBC on, then ran it up to 1500 slowly, took about 30 minutes, and held it for 40 minutes. I'm tempering it at 450 for 4 hours first time and then going to freeze it for a day or two and then temper at 400 for four hours. Should get around RC 59-61.
That sound right for a big bowie??
Thanks for all the tips and pointers and help you guys are sharing!!!!!!!!!!!!
God Bless!!!!!
 
Man, you are LUCKY you didnt shatter that blade when you tapped it on the marble if it was a newly heat treated and untempered blade. Some recently ht'd blades you can snap by looking at them funny prior to temper.
 
What kinda steel is it? got any pics? :D I am also going to try to be at TrackRock on that Saturday. i had a blade made from 1080 when i had first started doing blades that i had quenched and cleaned and since it was late at night decided to wait til the next afternoon after work to temper it (i dont like having anything on when i am not home). Well when i got home from work and got in the shop to temper it the blade looked kinda funny, so i got a magnifying glass and looked at it close, bunches of tiny tiny cracks running all the way up to where the clay had been (hamon area). needless to say it was ruined just from waiting. there were no cracks when i had sanded it clean, i looked for them and did a quick dunk in Radio Shack etchant to see where the hamon would be. I learned from that one.
 
I use the slotted firebrick and have had no problems at all. I've also done rockwell tests all over the blade - including 1/4 inch from the edge. I was looking for any issues with plate quenching but it would have shown any problem with the brick touching as well. No more than 1 RHC point difference anywhere. Seems to me that fire bricks are a great way to go. A 'heat sink' pulls heat away from something. In the first place, it can't do that if the temperatures are the same - and why in heavens name would it happen less with a steel rack than a brick?

Rob!
 
Terry, it's L6.
It's also in the oven soakin at 450 right now! :D
Kit Carson taught me to do the first temper as soon as you can handle the blade.
I diverted from that plan a little with this one since I cleaned it some pretemper but I don't think it's cracked.
I'll know in about 2 1/2 hours, ugh!
 
are you using L6 flatbar? if so where are you getting it from? I have been thinking about trying some L6.

Terry
 
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