straightening blades
Posted by William
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straightening blades February 23, 2025 06:33PM |
Registered: 4 years ago Posts: 20 |
Post heat treat, I sometimes get blades that are no longer straight. My heat treater is far away so simply annealing them and straightening and re-heat treating is prohibitive.
I usually use a 3 point set-up in a vise, with some heat. If the blade will fit in the oven it gets a final temper to relieve stress. Eventually I will have a tempering oven that will fit the straightening jig plus blade.
Lately I have seen carbide tipped hammers being used to straighten blades by peening. Interestingly they are shown peening the inside of the curve, to spread out that surface and push the blade straight, opposite to working sheet metal. Many are raving about these little hammers. I think the effect might be similar to how sand blasting will push thin blades away from the nozzle.
I made one of these hammers to try out, using a .25'' carbide ball in a light and junky hammer. Results using a polymer anvil:
On an old French made slicer/carving knife... success! It took more taps than I expected.
On a Sabatier all-metal slicer/carving knife... also success!
On large full-hard power-hacksaw blade... no effect. Too wide?
On an S-7 sword blank (no bevels yet)... nothing. Too thick?
On an Olfa blade (already straight but I wanted to see if it would curve)... blade crumbled to bits under very light taps. Pieces mostly sat on the anvil instead of shooting off like they normally do.
On an Olfa blade using a steel anvil... blade curves towards the hammer then cracks, again without shooting pieces around.
When I saw what happened to the Olfa blade I really started to worry about what is happening to blades processed in this way.
More experiments to come.
I usually use a 3 point set-up in a vise, with some heat. If the blade will fit in the oven it gets a final temper to relieve stress. Eventually I will have a tempering oven that will fit the straightening jig plus blade.
Lately I have seen carbide tipped hammers being used to straighten blades by peening. Interestingly they are shown peening the inside of the curve, to spread out that surface and push the blade straight, opposite to working sheet metal. Many are raving about these little hammers. I think the effect might be similar to how sand blasting will push thin blades away from the nozzle.
I made one of these hammers to try out, using a .25'' carbide ball in a light and junky hammer. Results using a polymer anvil:
On an old French made slicer/carving knife... success! It took more taps than I expected.
On a Sabatier all-metal slicer/carving knife... also success!
On large full-hard power-hacksaw blade... no effect. Too wide?
On an S-7 sword blank (no bevels yet)... nothing. Too thick?
On an Olfa blade (already straight but I wanted to see if it would curve)... blade crumbled to bits under very light taps. Pieces mostly sat on the anvil instead of shooting off like they normally do.
On an Olfa blade using a steel anvil... blade curves towards the hammer then cracks, again without shooting pieces around.
When I saw what happened to the Olfa blade I really started to worry about what is happening to blades processed in this way.
More experiments to come.
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Re: straightening blades March 07, 2025 01:55PM |
Registered: 4 years ago Posts: 20 |
Tried the hammer on a nice Henckels Professional chef knife... thousands of hits and zero effect using the soft anvil. I gave up and straightened using a 3 point jig in my vise with a little heat.
The blade felt hard but is now covered in little dents, so the hammer is deforming the metal but I wasn't getting the desired result.
Really weird results with the hammer so far.
The blade felt hard but is now covered in little dents, so the hammer is deforming the metal but I wasn't getting the desired result.
Really weird results with the hammer so far.
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Re: straightening blades June 29, 2025 12:46PM |
Admin Registered: 4 years ago Posts: 525 |
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