ok so here is my delima, first time for me but i know not for the majority here so looking for answers tips. what i have is a forged 5160 blade. 3 inchs long from ricasso to tip. distal taper forged into blade tip is approx .35 and spine at ricasso is .150. blade is 1.20 inches wide this was forged down from JD load shaft. before ht was very symetrical, i draw file and takes some time to get everything nice and even. after ht i dont recall seeing a bend to the blade i even looked down spine since i knew that would be time to try and fix any bends. after temper i now have a bend that starts at mid way of blade and is about a peenies thickness curve. My question is now thats it ht how do i fix it? do i do the ht over and hope it dont bend or do i anneal it and grind it straight? or is there a way to fix now with out doing ht over. after forgeing i normalized 3 times and then annealed it. after all file work and grider work i normalized 3 more time in reducing heats. then did the heat treatment. this bend crap is new to me never had it happen before and i put alot of time into this blade , would like to salavage it. thanks Pete.
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how to fix bent blade after ht
- Thread starter Dakota 11
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Dakota 11
I've had to straighten about 5 blades so far. What I do is grind the scale off after tempering. Then I heat the spine of the blade (where it need straightened) with a soldering torch until it turns blue, then quickly slide it into the jaws of a vise that is just cracked open, slide it in to as far as where the bend is then give it a torque look to see if it is straight - if it needs more give it another quick torque then into water to stop the heat from spreading to the edge.
I've had to straighten about 5 blades so far. What I do is grind the scale off after tempering. Then I heat the spine of the blade (where it need straightened) with a soldering torch until it turns blue, then quickly slide it into the jaws of a vise that is just cracked open, slide it in to as far as where the bend is then give it a torque look to see if it is straight - if it needs more give it another quick torque then into water to stop the heat from spreading to the edge.
Last edited:
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- Jul 27, 2003
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Keep in mind Mete's recommendation above.
I have done this successfully numerous times:
Give it the first tempering cycle.
Then, clamp the blade to a 1/4 bar of steel. But, place a small shim under the tip area so that when you clamp with a small C-clamp, you not only take the bend back to straight, but a little PAST straight the other way! Get it?
Give it the second temper while clamped up and let it come down to completely cool inthe oven.
You might just find that it is perfectly straight!
I have done this successfully numerous times:
Give it the first tempering cycle.
Then, clamp the blade to a 1/4 bar of steel. But, place a small shim under the tip area so that when you clamp with a small C-clamp, you not only take the bend back to straight, but a little PAST straight the other way! Get it?
Give it the second temper while clamped up and let it come down to completely cool inthe oven.
You might just find that it is perfectly straight!
- Joined
- Sep 27, 2004
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I have 5 blades with nice, short wharncliff blades that I use in the shop from attempting to straighten. I can pull it off 90% of the time and fix it on the grinder, but have broken a few that went haywire when my clay popped off one side and not the other.
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- Oct 3, 2003
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what!!! GREAT INFORMATION!!!
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- May 5, 2005
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Awesome tip Karl. Thanks alot.
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- Jan 28, 2008
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Couldn't you avoid the whole problem in the first place by clamping it between plates while tempering from the get-go? If I read the OP right, his warpage didn't occur until after the tempering portion of the heat treat. Is that a common thing? Like, the blade will be straight after hardening but will warp during temper? I ask because I've personally heat-treated all of two blades and one snapped in half and the other has a (previously existing, I think) crack in it.
i usually dont get bends or warps is first for me so not sure what caused it. im pretty sure when i looked down the spine after the quench it was stright. is why i think the bend came during temper process. i could be wrong though. temper was immeiate after quench in pre heated oven. not sure why or why internal dynamics would cause it to bend during temper would love to know. either way at this point the blade is nice and straight.
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- Mar 31, 2008
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I was gonna suggest using a Wayne Goddard style setup with 3 brass rods until I read Karl's suggestion. The next time I have a blade warp in the quench, I'm gonna try Karl's idea. Great information!