How do you straighten new warped stock?

[Daniel Fairly Knives]

I have some 1084 fg I'd like to use but the piece I got in looks like a recurve bow! It was packed with a bunch of other straight steel but must have been bent prior. I also have some new 5160 that has a dogleg on one end and various other pieces that are bowed or warped.

I can bend it pretty straight by hand but were talking knives here, they have to be dead straight.

How do you get the steel straight?

 

[Justin King]

Get it as close as you can by hand or with a 3-point jig, grind it out, and sent it to Peter's for HT, is the easiest. They come back straight, just like magic!
Seriously, though, when that isn't an option I get it as straight as I can, then for air hardening stuff, finish flattening on granite and sandpaper (or a disk grinder if you have one), and hope it comes out of HT still flat. For oil hardening, I wait until after the quench to flatten it on abrasives.

 

[Daniel Fairly Knives]

Get it as close as you can by hand or with a 3-point jig, grind it out, and sent it to Peter's for HT, is the easiest. They come back straight, just like magic!
Seriously, though, when that isn't an option I get it as straight as I can, then for air hardening stuff, finish flattening on granite and sandpaper (or a disk grinder if you have one), and hope it comes out of HT still flat. For oil hardening, I wait until after the quench to flatten it on abrasives.

That is about what I'm doing now, makes sense! I thought maybe there was some trick to it or something, lol.

Thanks!

 

[Justin King]

Only other trick I know of is to straighten during the temper but the trick there is grinding a straight knife out of a warped bar in the meantime. Unfortunately, once a bar is bent or warped, grinding/sanding is about the only way I know to get it perfectly flat again, and it's not necessarily easy even then, as you already know.

 

[jawilder]

I am finishing a knife using the 1084fg and had the same problem. I was hoping to straighten it during HT but it didn't. It got very bent in the quench. I used Rick's method to straighten during temper and the bend from the quench came out but the origional bow is still there, but not as bad.
Jason

 

[Daniel Fairly Knives]

Only other trick I know of is to straighten during the temper but the trick there is grinding a straight knife out of a warped bar in the meantime. Unfortunately, once a bar is bent or warped, grinding/sanding is about the only way I know to get it perfectly flat again, and it's not necessarily easy even then, as you already know.

Thanks again Justin, that makes sense.

I am finishing a knife using the 1084fg and had the same problem. I was hoping to straighten it during HT but it didn't. It got very bent in the quench. I used Rick's method to straighten during temper and the bend from the quench came out but the origional bow is still there, but not as bad.
Jason

I am trying to avoid quenching a knife that isn't straight. I have used Rick's method successfully to straighten a tiny warp that happen during quench but I don't even want to grind steel that isn't straight.

The 1084 was just an example, the other 1084 stock I have is dead straight, I didn't want to lead people to believe that it was especially problematic.

Did you straighten the piece and have the bow come back during quench?

 

[gomipile]

What do you mean by a 3-point jig? I assume you're not talking about the one they use for drilling bowling balls at the pro shop.

 

[Hengelo_77]

Have the steel on two blocks on your workbench, bend facing up (one block on either side)
Take a good clamp, like a C clamp, and twist the bend down just past straight.