ddavelarsen
Well-Known Member
You guys have helped me determine when the best time is to correct a warped blade - right out of the quench - which seems to be working great. But I have an even more basic question - why the warp in the first place?
Here's my recent experience. I've been heat treating 3/16 O1 mostly. I use an Even Heat oven, preheat to 700 before applying PBC, normalize for half an hour at 1250, ramp up to critical at 1550 and soak for 10-15 minutes.
My quench tank is at about 140-150 degrees with circulating oil; I quench in Houghton Quench G.
When I'm ready to quench, I remove the blade with a large pair of pliers and immediately submerse in the tank, edge down, and move the blade forward - lengthwise - back and forth through the oil. No side to side movement at all, I'm very careful about that.
Here's the rub. Almost every blade comes out warped where I've held it with the pliers. Doesn't seem to matter what part of the blade I grab, that's where it warps. Sometimes its very minor, but other times it's pretty significant. The worrying part is that this almost always happens. And if it's a worse warp, I've cracked some blades trying to straighten them, even still somewhat hot from the quench. (I use a three-point system in my large vise to counter warping.)
Any ideas what's causing this? Is it the pliers having too much contact surface on the steel? I've ground the jaws smooth - no ridges - but they do pretty much grip the blade with the jaws flat on each side.
I have a pair of tongs that because of the angle of the jaws, would probably only grasp the top edge of the blade when I pull it out of the oven. Think using those would make any difference? A friend suggested lifting the blade from the oven with a wire through one of the holes in the tang. Think I might make something to try that, but I also think it might take enough time that I'd lose some heat in the process of getting hold of the blade.
Any and all ideas are really welcomed here. This is frustrating and disturbing. I never had this issue when I was heat treating in my propane forge and only bringing the edge up to critical before quenching in vegetable oil - those were the "old days" when things worked right...
Well, thanks for listening to me whine, and I'd sure appreciate any insight you gents might have.
Here's my recent experience. I've been heat treating 3/16 O1 mostly. I use an Even Heat oven, preheat to 700 before applying PBC, normalize for half an hour at 1250, ramp up to critical at 1550 and soak for 10-15 minutes.
My quench tank is at about 140-150 degrees with circulating oil; I quench in Houghton Quench G.
When I'm ready to quench, I remove the blade with a large pair of pliers and immediately submerse in the tank, edge down, and move the blade forward - lengthwise - back and forth through the oil. No side to side movement at all, I'm very careful about that.
Here's the rub. Almost every blade comes out warped where I've held it with the pliers. Doesn't seem to matter what part of the blade I grab, that's where it warps. Sometimes its very minor, but other times it's pretty significant. The worrying part is that this almost always happens. And if it's a worse warp, I've cracked some blades trying to straighten them, even still somewhat hot from the quench. (I use a three-point system in my large vise to counter warping.)
Any ideas what's causing this? Is it the pliers having too much contact surface on the steel? I've ground the jaws smooth - no ridges - but they do pretty much grip the blade with the jaws flat on each side.
I have a pair of tongs that because of the angle of the jaws, would probably only grasp the top edge of the blade when I pull it out of the oven. Think using those would make any difference? A friend suggested lifting the blade from the oven with a wire through one of the holes in the tang. Think I might make something to try that, but I also think it might take enough time that I'd lose some heat in the process of getting hold of the blade.
Any and all ideas are really welcomed here. This is frustrating and disturbing. I never had this issue when I was heat treating in my propane forge and only bringing the edge up to critical before quenching in vegetable oil - those were the "old days" when things worked right...
Well, thanks for listening to me whine, and I'd sure appreciate any insight you gents might have.