Problem keeping blade straight...

Don Rac

Don Rac

Joined
Oct 3, 2001
Messages
1,191
I had a bowie blade at 3/32 on the spine all the way down and one other one at about 5/32 on it's spine. I heat treated the blades but the suckers started curving toward the left, now how the he11 did that happen? Did I do something wrong in the process? Sorry kinda new at this and starting with "beginner" equipment.
 
Don
There should be many good folks chime in on this problem. I think all knifemakers go through these problems and learn ways to cure them after making several blades.
Here are a couple of ideas.
The condition of the steel before you process it is important.
Are they ground as close to the same on both sides as posible?
If not the blade will warp.
What steel did you use?
What condition was it in when you got it i.e. hot rolled, as rolled,
from plate , from bar, annealed, sub annealed.

If is "as rolled steel" this could be one of the problems.
A good process is to first anneal a bar like this to dead soft. Then start working it if you using the stock removal method.
If it is forged , did you anneal before grinding and heat treating?
This will cause warp if not
Hot rolled is annealed sometimes but not always.

Buy steel that is fully processed and annealed.

Just a few small things to look into.
 
Thank you Darrel. Looking at it closely, it looks like theres a really small dip in the grind, so maybe I took off a little too much at the blades middle. I wanted to keep the blade thin and light, but it's about 9 3/4 inches long. I probably need to keep a closer eye on my grinding.
 
Don,

I made a few filets out of 1/8" flat stock and after grinding in the bevels and cleaning up they were pretty dog gone thin, I always normalized at least one time after grinding and then when heat treating be sure you bring both sides of the blade up to heat as equally as you can by rotating it constantly, and becareful not to over heat, those thin blades heat up pretty damn quick. Other than that its just practice,practice,practice. :D

Good luck

Bill
 
Also check that you apply even heat when bringing up the degrees. Uneven heating will curl it quick. Sometimes they will bend no matter what you do. Then you straighten.
 
Thanks for the heating advice guys, I appreciate it alot. By the way Bill, I like that fighter you made, looks real nice. Peter, your sig says you won an ugly knife contest? I probably shouldn't look for the one I buried out in my back yard, first knife I ever made from ALUMINUM of all things. That knife had to be the fugliest thing I ever created.:)
 
Don,

Thanks for the compliment on the fighter, and I had that Ulgy Knife Contest won until Peter cheated and brought in that ringer, I also think that he gave Indian George a couple of bucks under the table too. :D :D Come on peter fess up.

Bill
 
I'm a seasoned professional ugly knife maker now Bill. I've got one I'm working on now that I have to wear a welding helmet to just look at it.:eek:
 
I don't know how you are making these knives. If you are grinding, only make a couple of passes per side, then do the same to the other.
It is a great temptation, to stay in the groove on one side, till done. This stresses the steel, and it will warp in heat treat. Hope this has helped a little.
 
Thanks Mike, I usually do the same number of passes per side but since these were thin I think I might've lapsed on that a little.
 
Another thought, especially for smaller knives, might be to heat treat first then grind the blade. Just make sure when you're doing it this way to not overheat the blade when grinding. This method was suggested to me a while back and it works well.
 
Thanks for the extra info Peter. This is really a great place to ask questions if you want to learn a few things, thanks guys. :)
 
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