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How do you fix a bent blade?

Posted: Mon Oct 17, 2011 5:48 pm
by MikeEngland
Is there any safe/smart way to straighten a bent or warped blade?

Re: How do you fix a bent blade?

Posted: Mon Oct 17, 2011 6:02 pm
by Iron Hoarder
Very gently in a vise with three pieces of brass rod. Two on one side and one on the other.

Re: How do you fix a bent blade?

Posted: Tue Oct 18, 2011 1:28 am
by FRJ
That does seem like a very smart method.

Re: How do you fix a bent blade?

Posted: Tue Oct 18, 2011 2:15 am
by OLD GAR
Just be ever so careful though. Many of the high quality knife blades are near 50+ Rockwell "C" scale hardness. That is why you see broken blades on really good knives - - enough to make you want to cry. On the other hand if it bent, ::tear:: you might be straighten it out ::woot:: .

Re: How do you fix a bent blade?

Posted: Tue Nov 29, 2011 4:23 am
by whitebuffalo58
Just an observation. Did ya ever notice that it's not that hard to bend a knife blade, but it's nearly impossible to bend it back? Why is that? ::hmm::
A couple of times, i've gotten away with cold forging a bend out on a flat anvil. I used an 8 oz. detailing hammer and just let the weight of the hammer do the work. Took my time and little by little it eventually worked the blades to very near straight. I stopped as soon as the blades were able to function properly. (I didn't see any need for pushing my luck)
It left a few light hammer marks, but the times I did it were on EDC knives, so I wasn't real concerned with clean up on the blades. Probably wouldn't have taken much more then some light sanding though.
My brother once pointed out that a blade can be lightly "warmed" as long as you don't warm it to the point of getting color. Haven't had the opportunity to try it, but thought maybe warming in a toaster oven to say 250-300 degrees might help reduce the chances of breaking while forging. ::shrug::
Bottom line is, every method is risky, short of removing, heating, straightening and reheat treating. Well, I guess that's even risky...just a different kind of risky. :D

Re: How do you fix a bent blade?

Posted: Tue Nov 29, 2011 6:17 pm
by knifemaker3
OLD GAR wrote:Just be ever so careful though. Many of the high quality knife blades are near 50+ Rockwell "C" scale hardness. That is why you see broken blades on really good knives - - enough to make you want to cry. On the other hand if it bent, ::tear:: you might be straighten it out ::woot:: .
I think you meant 60+ Rockwell "C" scale....or at least I hope so :lol:

Re: How do you fix a bent blade?

Posted: Tue Nov 29, 2011 7:25 pm
by Diligence
The most surefire way I've ever used to fix bent blades, was to very carefully tap it on the side of my stiddy to straighten it out....then just give it one more firm tap to be sure it was straight, have it break, and make a new one.

lol...seriously though, I've only had marginal luck straightening bent blades. Sometimes it works and sometime it doesn't as far as I have experienced, and it depends on the type of steel, hardness and tempering that was used.

J

Re: How do you fix a bent blade?

Posted: Tue Nov 29, 2011 7:30 pm
by gringo
how bent???
photos please.

dudley should chime in here...since swords have issues with being bent more often than knives.

in fencing class...
if you bent your foil, the correct method of straightening the blade was to place the sword tip down, at an angle, and step gently on the blade at the point of the bend.

might be difficult to step on a pocket knife and come away happy.

Re: How do you fix a bent blade?

Posted: Tue Nov 29, 2011 7:55 pm
by orvet
gringo wrote: might be difficult to step on a pocket knife and come away happy.
:shock:



::rotflol:: ::rotflol:: ::rotflol::
Thanks Donald, I needed that!
The visual in my head was too funny! :mrgreen:

Re: How do you fix a bent blade?

Posted: Wed Nov 30, 2011 9:43 pm
by glennbad
I've had very little luck straightening a bent blade. The only time it works for me is during crinking, where I find the tangs can be a little softer and can be tapped some with a hammer. Near the tip, not so much... ::dang::

I have a swiss army knife where the main blade is slightly bent, and doesn't sit right on the close. Every few months, I discover it again and try to bend it back. Haven't succeeded yet...

Glenn