View Full Version : need to straighten a blade

07-02-2003, 05:39 PM
I've just finished profiling a blade (stock removal) and noticed it is slightly bowed. I don't think I overheated it. May have been in the stock to begin with. Anyway I want to straighten it. It is 1/8 x 1 1/2, 1084. Can I heat this to a certain point (?) and then lay it on a flat surface.... put weight on top? And after doing whatever will it effect my heat treat. I use an oven. This bow is very slight, maybe almost insignificant. But it bugs me.

Thanks for any help.

07-02-2003, 09:48 PM
You have to promise me you won't tell this to my wife.
I have had good luck heating the blade to 350F and rolling it back and forth across a rolling pin. Whilst pressing down on each end. Letting the pin roll to minimize stress points. This is good for generalized curve with no appearant kink or bending point. Blade across the pin, not pin across the blade!
Was it flat when you started???
Look carefully and see if there is more ground off one side than the other.
If it is "ever so slight", a simple triple normalize and full anneal may take care of it for you.
Normalize is heat to non-magnetic and cool in still air to either black heat or room temperature depending on who you listen to.
Anneal you go back to non-magnetic and allow to cool slowly in a can of Vermiculite, ashes, or lime. Vermiculite is probably easiest.
If it recurves on you, stress from grinding too much on one side is probably present. If that is the case be ready to restraighten it after the quench when you harden it. You can sometimes pull the bend out after hardening if you do it IMMEDIATELY after quenching and BEFORE it makes it to room temperature.
Hope this helps. Works more often than not.
Enjoy, Ken

07-03-2003, 06:41 AM
Thanks Ken, sounds good. I'll try the rolling pin first and see how it does.

Jerry Hossom
07-03-2003, 10:16 AM
Just bend it back. It happens to me all the time, because I grind my blades pretty thin. I just lean on it until it's about right, then take care of any small residual bend when I finish grind. You can even hit it with a hammer if you have to.

You gotta teach that steel who's boss!!! :D

07-03-2003, 10:33 AM
Jerry, sounds too easy but I'll give it a try. Just found a second one bent the same way. Never had this happen before. I do think there was a little warp in the steel when I got it. I'll teach em who's boss!:D

07-03-2003, 11:10 AM
a good way is to put it in the vise and place brass rods where the bend is .

Jerry Hossom
07-03-2003, 11:38 AM
Careful with the brass rods, that might put a sharper reverse bend in it than you want. If it's just a gradual bend, then I usually just rest on end one something to elevate it then lean on the blade a little until it submits. Steel sometimes comes that way, so check it before you grind. It less traumatic to do it then.

07-03-2003, 02:23 PM
I hit it with a hammer. It's straight as an arrow. Now I'll have to see what it looks like after heat treat. Thanks. I'll give a final report after HT.

07-04-2003, 12:22 AM
After clamping it in a vice and thumping it with a dead blow mallet it was nice and straight. Came out of heat treat as straight as it went in. All is well. Thanks for all the suggestions. I've stored them away for future use.

07-04-2003, 07:52 AM
Prior to heattreat as Jerry said, just do it. Any way that will work is fine. I have to check myself constantly, especially with forged blades, to make sure that I'm not grinding crooked...which I usually am.:( After heattreat though it can get real touchy/feely trying to straighten....and it WILL mess up your blade if you get it too hot.