Another way to take care of warped blades

razor-edge-knives said:
Just curious, how do you grind carbide? Isn't the only way to do this with diamonds?
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I used a diamond disk in a Dremel tool to shape it while the carbide was spinning in a drill press. The diamond disks are available cheaply from Harbor Freight. I think they come in a set of five for around five bucks.

The piece of carbide I used was 2" long and I cut it in half. To do that, I scored it with the diamond disk. The diamonds on the edge of one of the disks last just long enough to get a decent score line. I then put the piece in a vice, put a rag over it so the pieces wouldn't go flying around the shop and then hit it with hammer to snap it in half. I had to hit it pretty hard before it broke, but I got a relatively clean break.
 
I use a green wheel on the bench grinder. When I need to reshape the point in the auto peening machine I use a diamond sharping stone and hand dress the point/edge back onto it. I seam to get good life out of it and only have to reshape the point every 500 blades or so.
 
JTknives said:
I use a green wheel on the bench grinder. When I need to reshape the point in the auto peening machine I use a diamond sharping stone and hand dress the point/edge back onto it. I seam to get good life out of it and only have to reshape the point every 500 blades or so.
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Is a "green wheel" just a regular silicon carbide wheel or something special?
 
It seems that it takes so little to straighten a blade with a carbide hammer.
My imperfect logic tells me that it would take equally as little to make a blade warp, such as when a person, oh I don't know, uses a blade??? ...Or sets it down, or accidentally drops it on a hard surface.

- Paul Meske, Chippewa Falls, WI
 
lonepine said:
It seems that it takes so little to straighten a blade with a carbide hammer.
My imperfect logic tells me that it would take equally as little to make a blade warp, such as when a person, oh I don't know, uses a blade??? ...Or sets it down, or accidentally drops it on a hard surface.

- Paul Meske, Chippewa Falls, WI
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The carbide hammer causes a divot. The way I understand the process is that the plastic deformation will cause the material to expand laterally due to volume conservation, and this expansion pushes the blade straight and creates some residual stress. I don't see that happening during normal use, but I could see where grinding the bevels could make the blade curve again, because the impacted area may be removed. So far, that has not happened to me, but I have had AEB-L blades warp during grinding before.
 
Herbert is correct. Plastic deformation is what is happening. As the hammered side expands, the blade bends toward the unhammered side. Thus is the same principle as curling a strip of paper or ribbon. When you draw it across the scissors blade it stretches the one side, making the paper/ribbon curl toward the other side.

As to bending in use, unless there is heavy stress on one side only, the finished knife will stay straight
 
I have been hammering away with a 14mm masonry drill at this 4mm cleaver in 14c28n that took a large bow across whole length. First I started easy and nothing was happening. Then I started smacking stronger and things started moving, it's still maybe a 1,5 mm out of true. My question is, can one overdo it or cause damage to the blade with excesive denting? I wonder how much work it is going to be to grind it all out...
Sx3SFOb.jpg


420hc and becut came out straight. All 3 14c28n blades had warps, partially even in different directions..
 
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FredyCro said:
I have been hammering away with a 14mm masonry drill at this 4mm cleaver in 14c28n that took a large bow across whole length. First I started easy and nothing was happening. Then I started smacking stronger and things started moving, it's still maybe a 1,5 mm out of true. My question is, can one overdo it or cause damage to the blade with excesive denting? I wonder how much work it is going to be to grind it all out...
Sx3SFOb.jpg


420hc and becut came out straight. All 3 14c28n blades had warps, partially even in different directions..
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Grind it down as much as u can closer to the final bevel. Then straighten it

your backing should be an anvil
 
HSC /// said:
G

Grind it down as much as u can closer to the final bevel. Then straighten it

your backing should be an anvil
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It's gonna be a short bevel, most of the blade is going to be flat. Shouldn't I get it flat first? Yeah, I wasn't sure on the backing, used a piece of wood no floor.
 
FredyCro said:
It's gonna be a short bevel, most of the blade is going to be flat. Shouldn't I get it flat first? Yeah, I wasn't sure on the backing, used a piece of wood no floor.
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Anvil will be more effective

it’s easier to move the metal when it’s thinner. You will have to decide what’s right for you on this one

4mm is pretty thick. Your options are to grind it down or hit it harder
 
FredyCro said:
It's gonna be a short bevel, most of the blade is going to be flat. Shouldn't I get it flat first? Yeah, I wasn't sure on the backing, used a piece of wood no floor.
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Yeah I use an anvil and it works better, the wood is just absorbing all the energy. I had a small Damascus blade warp bad on me a couple days ago probably just under a 6mm warp in the middle of the blade with the tip and tang flat, tempered twice without doing anything to it then used the carbide hammer and had it straight in under 5 minutes with probably 80-100 taps ground the both sides clean and nothing moved or bent back I was able to get all the divots out with a 60 grit belt pretty quickly. Also as a note the blade was probably 3.5-4mm thick to start so it does work for thicker blades.
 
Theoretically I have an anvil, but its not in the shop yet :)

Yeah, the wood was to stop the ringing and noisy neighbours, I understand it's not the best way to do it.

Gonna smack it some more, shouldn't take much anymore, but it's stubborn, I just got a bit worried cause there is a lot of divots there now.

Thanks for the help, guys!
 
See ...that is the problem with this discipline. Years ago I w as actually intrigued by the heat treating process. Though, every time now I think about building an oven, I think, “ but then I will need good quenching oil and a container, ... and a decent tempering oven, ... and a carbide hammer to straighten, ... and an anvil (or facsimile) to hammer on, etc, etc. so far it seems easier to send my few blades out to people who really know what they are doing :-)
 
Cushing H. said:
See ...that is the problem with this discipline. Years ago I w as actually intrigued by the heat treating process. Though, every time now I think about building an oven, I think, “ but then I will need good quenching oil and a container, ... and a decent tempering oven, ... and a carbide hammer to straighten, ... and an anvil (or facsimile) to hammer on, etc, etc. so far it seems easier to send my few blades out to people who really know what they are doing :)
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I know what you mean. It's all fun, until it is not! Now I need a hardness tester as well. :)
It's satisfying to know that you did it all yourself, but for a hobbyist it doesn't really pay out. I will sell some blades, just not yet.
 
Scaniaman said:
Yes, it is a good addition. Sometimes the results are surprising.
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I am hunting on eBay and local classified, but no luck for now. I might opt out for a new unit in the end. There was a good unit made by Emco recently but it was huge, and I think the price of service would probably amount to a new machine anyway.
 
FredyCro said:
I am hunting on eBay and local classified, but no luck for now. I might opt out for a new unit in the end. There was a good unit made by Emco recently but it was huge, and I think the price of service would probably amount to a new machine anyway.
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I got my Oxford/Grizzly at zoro.de with a 15% discount code and free shipping for well under 900 euros. They have regular discount codes in their newsletter.
 
Scaniaman said:
I got my Oxford/Grizzly at zoro.de with a 15% discount code and free shipping for well under 900 euros. They have regular discount codes in their newsletter.
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Thats a good deal, but still a considerable amount :)
 
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