[Chris L]

Sure many metals and steels can be forcibly bent into another shape, but really my question of course relates to razors. Specifically, finished razors rather than razors in the process of being fashioned.

Your typical vintage blade. We've all experienced "warped" blades. I was thinking, if a clamp was made using a few small straight edges sandwiching the edge lengthwise and two more straight edges clamped the spine lengthwise and finally.....some straight edges clamped down both the spine and the edge crossway, would this or a similar concept correct the warp and bring the blade into trueness? Orthodontia for razors with problems.

Or...after removing the clamps, would the steel revert back to its pre-clampning shape?

Chris L

[nun2sharp]

I do not claim to be an expert, so my opinion really means nothing,BUT seeing that razors are made of very hard steel I would think the stress would crack/break the blade entirely no matter how you wrapped it. It might be done if you annealed it first. Dont take any of this to heart, its just my 2c, wait for someone who knows before making a decision.

[Mike Blue]

If the blade was differentially hardened, meaning the back was softer than the edge, your method might work. But if the blade is through hardened, I'd agree with Nun2, it's more likely to completely separate. If the blade is full hard, it likely happened during the original heat treatment. It's amazing that so many blades made it out into the public domain for use in that condition.

When making a new razor, that's why it's recommended to leave things a little thick at the edge before heat treatment. That way if there is a little warpage, at least you can grind the edge straight and compensate.

The real trouble with reheating and annealing "old" razors is that they are already ground down to thin. The heating process can cause scale loss on the surface which will require regrinding and the whole blade will be different than what was started. It could be done, but it's risky even with the right equipment like salt or lead baths and still have something left that looks like the original. But changing the heat treatment means its likely to be a whole different razor even if it looks the same.

Thoughts to ponder.

[Russel Baldridge]

Agreed, any stress needed to deform hardened steel would be great enough to risk serious breakage. You would need to stress the steel beyond the elastic limit to reverse a warped edge which would require more of a concave clamping mechanism than the flat bars. And to make matters worse, it would be fairly imprecise if it could be made to work since the edge is so thin and could easily be warped into the other direction rather than straight, where you want it.

[Chris L]

Stupid warped vintage blades!

I figured as much. Thanks for the info, guys. In a perfect world, all blades that I shave with would lie perfectly flat (on both the front and back side of the blades mind you) on wide hones and be a pleasure and a breeze to hone and maintain. I guess that would take half the fun out of it too, though (substitute "fun" for the word frustration or any four letter word you may choose depending on your mood).

I guess that's that. I will have to eventually make my own shaving implements in which case then my goal WOULD be to have the end result lay beautifully flat on the flat honing surface. Now THAT'S worth daydreaming about!

Chris L

[JoshEarl]

Chris,

I believe steel does have a memory, but it's possible the warp actually represents the steel returning to the shape it was "remembering." I've heard of blades made of straightened coil springs developing a curve when quenched. Not sure if it's true.

One other option for straightening blades would be to soften the back of the blade while keeping the edge cool. You might be able to keep the edge submerged in water and heat the spine with a torch. That would partially anneal the spine and allow you to straighten it.

Probably more trouble than it's worth, but it might be fun to try sometime.

Josh

[kaptain_zero]

I'd just like to get something clarified. Chris said "In a perfect world, all blades that I shave with would lie perfectly flat (on both the front and back side of the blades mind you) on wide hones". This is where I became suspicious. If a blade is warped, it must lay uneven on *both* sides of the spine only in the opposite direction. I have a razor that lays perfectly flat on one side and has a straight edge from the factory but rocks all over the place on the other side. I don't consider this blade warped, just very poorly ground on that side that rocks and you can clearly see there is a hump in that side of the spine as well as tell tale signs in the hollow indicating the material is thicker in the same spot. I'm thinking of perhaps getting one of the grindmeisters to introduce that blade to a belt grinder as I'm not the man for that particular job but I'm sure it would be a touchy fix considering it's pretty much a full hollowground blade. I might just straighten out the spine where it touches the hone and live with the uneven blade/bevel that will result. Still, I just wanted to point out that sometimes blades are not warped if they will rest on the hone properly on one side but not the other. A blade that is warped can lay flat on one side but there will be a hollow in the middle portion of the spine and there will be a corresponding hump on the other side that lets the blade rock back and forth in which case the spine will look like a banana from up top.


Christian

[Chris L]

Originally Posted by kaptain_zero

I'd just like to get something clarified. Chris said "In a perfect world, all blades that I shave with would lie perfectly flat (on both the front and back side of the blades mind you) on wide hones". This is where I became suspicious. If a blade is warped, it must lay uneven on *both* sides of the spine only in the opposite direction. I have a razor that lays perfectly flat on one side and has a straight edge from the factory but rocks all over the place on the other side. I don't consider this blade warped, just very poorly ground on that side that rocks and you can clearly see there is a hump in that side of the spine as well as tell tale signs in the hollow indicating the material is thicker in the same spot. I'm thinking of perhaps getting one of the grindmeisters to introduce that blade to a belt grinder as I'm not the man for that particular job but I'm sure it would be a touchy fix considering it's pretty much a full hollowground blade. I might just straighten out the spine where it touches the hone and live with the uneven blade/bevel that will result. Still, I just wanted to point out that sometimes blades are not warped if they will rest on the hone properly on one side but not the other. A blade that is warped can lay flat on one side but there will be a hollow in the middle portion of the spine and there will be a corresponding hump on the other side that lets the blade rock back and forth in which case the spine will look like a banana from up top.


Christian

Thanks for the additional clarification, Christian. I agree with you. I have used the term "warped" in this post rather loosely. I own truly warped blades (as you describe them) as well as more blades that are flat on one side and have issues, normally from what I have seen, on the spine of the other side screwing up the edge on the spine problem side from lying flat. Still, in my perfect world, my razors would lie perfectly flat, choruses would sing as I effortlessly hone my razors to sharply comfortable perfection each and every time. Yeah yeah, I know, dream on, Chris.

Chris L

[kaptain_zero]

Heh.... in my little warped, but perfect world, each and every razor would have a swayed back, bellied (smiling) edge and require serious body english to hone!

Oh, and to your original question... once steel has been hardened, if you move past the elasticity limit, you are permanently deforming the steel and that means breakage when it comes to hardened steel unless it's been tempered way beyond what razors are normally.

An interesting side point for some, aluminum does not have any elasticity... zero, zip! Yes, you can flex aluminum, but each and every time aluminum is flexed it actually adds to structural failure.... Steel if flexed within it's elasticity boundaries, is not affected and thus we have spring steel but not spring aluminum and this is why stress fractures are a common problem on aircraft where flex is unavoidable but steel is just too heavy to use.


Regards

Kaptain "Booze can cause brain fractures... I think" Zero

[floppyshoes]

Originally Posted by kaptain_zero

An interesting side point for some, aluminum does not have any elasticity... zero, zip! Yes, you can flex aluminum, but each and every time aluminum is flexed it actually adds to structural failure.... Steel if flexed within it's elasticity boundaries, is not affected and thus we have spring steel but not spring aluminum and this is why stress fractures are a common problem on aircraft where flex is unavoidable but steel is just too heavy to use.

I beg to differ on this. Aluminum has a very small elastic region, and steel can be flexed only so many times before it fails from fatigue (normally tens of thousands of cycles, but it will fail eventually)

In the subject of warped blades, I have nothing more to add that was not already mentioned by our esteemed bladesmiths. Once that sucker is teat treated, you're pretty much limited to material removal for shaping. This is not a problem if there is steel where you don't want it, but a major issue if there is none where you do want it.

[nun2sharp]

Originally Posted by floppyshoes

I beg to differ on this. Aluminum has a very small elastic region, and steel can be flexed only so many times before it fails from fatigue (normally tens of thousands of cycles, but it will fail eventually)

In the subject of warped blades, I have nothing more to add that was not already mentioned by our esteemed bladesmiths. Once that sucker is teat treated, you're pretty much limited to material removal for shaping. This is not a problem if there is steel where you don't want it, but a major issue if there is none where you do want it.

wished i were teat treated

[floppyshoes]

Originally Posted by nun2sharp

wished i were teat treated

I'm not sure what shocks me more; that I made a spelling error that slipped past my proof reading or that somebody actually read my post

[jimmyseymour]

Originally Posted by JoshEarl

Chris,

I believe steel does have a memory, but it's possible the warp actually represents the steel returning to the shape it was "remembering." I've heard of blades made of straightened coil springs developing a curve when quenched. Not sure if it's true.

One other option for straightening blades would be to soften the back of the blade while keeping the edge cool. You might be able to keep the edge submerged in water and heat the spine with a torch. That would partially anneal the spine and allow you to straighten it.

Probably more trouble than it's worth, but it might be fun to try sometime.

Josh

I saw this done in my bladesmithing class for the ABS. Heating the spine while keeping the blade in the water to straighten out a warped blade. Michael Connor's from winters was teaching the class. I didn't get to see the whole process but no pressure was placed on the blade. It was gently heated and it straightened itself. The guy who did it said he could feel it straighten.

A blade could also warp because it was not stress relieved properly, or at all before harding. If using an oil quench if you move the blade around to much you could also cause a warp.

[nun2sharp]

I would've like to have seen that.

[Chris L]

Originally Posted by nun2sharp

I would've like to have seen that.

+1 on that. Now THAT would be a viable service to be offered if it worked on a consistent basis. Man alive, I could see myself sending a small box of blades to a "razor straightener". Seriously. Alas....if it sounds to good to be true.........well, you know the rest.

Chris L

[Mike Blue]

Originally Posted by jimmyseymour

I saw this done in my bladesmithing class for the ABS. ... The guy who did it said he could feel it straighten.

A blade could also warp because it was not stress relieved properly, or at all before harding. If using an oil quench if you move the blade around to much you could also cause a warp.

I'd love to "see" him "feel it straighten" too. Must be using the Force. That and a coupla solid straight edges would show some good results.

Realistically, if the edge was flat and the blade honed properly, what difference, other than the aesthetic, would there be as far as the blade's ability to shave well? Now I suspect that razor manufacturers didn't much care that the spine had a warp as long as the edge was salvageable enough to hone/shave and sell.

Stress relieving: doesn't that occur after heat treatment? And, how will any quench cause warping by moving the blade around?

[Berticus]

I think there's only one kind of steel that can morph back into its original state. Don't remember what it was called, but I saw a video of it once. Basically you can warp it into any shape, but once you apply heat, it will morph back into its original state. But it's not something you would use as a razor since it's so flexible. In the demo video, the guy used a spring, he twisted it in all sorts of ways, and then heated it with a hairdryer. He said he thought it could be used to erect buildings quickly. The buildings would be made at a hardware store modularly, then they could bend it into a compactable shape and move it to the site, and then heat it and have it erect itself. Making a whole building would take only a day!

I'm certainly no blacksmith, but I believe the only way to bring the steel back into shape is if you reheat it and reforge it. Simply applying a force could break it.

[Mike Blue]

There are several alloys of stuff called memory metal. Here's one link: kinda cool really.

NiTi Memory Metal

But mostly small applications, and not blade steels.

[jimmyseymour]

Originally Posted by Mike Blue

I'd love to "see" him "feel it straighten" too. Must be using the Force. That and a coupla solid straight edges would show some good results.

Stress relieving: doesn't that occur after heat treatment? And, how will any quench cause warping by moving the blade around?

This wasn't a razor but a very big bowie knife. I was also incorrect in my writing. The convex side was heated and a little on the spine, not just the spine was heated. I'm sure with all that mass moving you would be able to feel it. It wasn't me who did it, so I can only repeat what he said. Maybe his feeling the blade straighten was more in his head while watching than anything.

stress relieving should be done during hardening especially for stainless steels. For stainless you let it soak for thirty minutes at a predetermined temperature. For a forged blade it could be argued that the normalizing process or the spheroidizing before intial heattreatment accomplish the same thing. There's no correct answer only personal opion on that one.

I was told again by Michael Connor that they moving the blade around (side to side motioin) during the quench causes the vapor barrier on one side of the blade to diminish causing one side to cool faster than the other. Up and down motion was ok and would help to break up the vapor barrier. If one side cools faster than the other then you will definitly have a warped blade. I've only had one blade warp on me but I believe it was due to poor grinding as I have just never moved a blade side to side when quenching. Remember the clay differiantial thickness is used to harden a samurai sword's also causing the curvature of the blade because the edge hardens far quicker than the spine. It's also why an uneven ground blade will warp. One side has less material than the other side and will cause one side to cool faster than the other and warp.

I have a book on making samurai swords and they talk about using heated copper blocks to change the curvature of the swords if it has to much or to little curvature. Heating the sides of the blades with the copper then laying it flat on the anvil and giving it a whack with a wooden mallet to straighten the blades, etc...

For sheetmetal and bodywork I've seen old timer heat the side of car panel up and mist water on the steel to cause it to shrink and straighten out some creases.

So depending on the steel type used and application will determine what is best for straightening a blade, or just throwing it away.

[Mike Blue]

A few comments:

stress relieving should be done during hardening especially for stainless steels. For stainless you let it soak for thirty minutes at a predetermined temperature. For a forged blade it could be argued that the normalizing process or the spheroidizing before intial heattreatment accomplish the same thing. There's no correct answer only personal opion on that one.

Ahem. Stress relieving occurs in two types. The first is to relieve internal stresses generated by heavy machining of clamped pieces. The second is tempering which relieves the internal stresses in steel caused by martensite formation against areas of non-martensite. I could use your Japanese sword example because that is a perfect illustration. So, the fact is, not personal opinion, stress relief is desirable when one of the above conditions exists in the material.

... the vapor barrier on one side of the blade to diminish causing one side to cool faster than the other. Up and down motion was ok and would help to break up the vapor barrier. If one side cools faster than the other then you will definitly have a warped blade. I've only had one blade warp on me but I believe it was due to poor grinding as I have just never moved a blade side to side when quenching. Remember the clay differiantial thickness is used to harden a samurai sword's also causing the curvature of the blade because the edge hardens far quicker than the spine. It's also why an uneven ground blade will warp. One side has less material than the other side and will cause one side to cool faster than the other and warp.

Martensite formation occurs at the speed of sound (770 miles per hour at 68F at sea level, about 13548 inches per second). Even in a great big bowie knife (1/4-5/16ths of an inch thick at the spine), I don't think that any wiggling about a human being could do will cause a warp to occur in the short amount of time available between the initial quench and the formation of martensite, unless some very specific conditions are controlled. About the only way to significantly alter quenching both sides of a blade to cause one side to cool faster than the other, would be to lay only one side of the blade on the surface of the quench bath.

From what you describe, the vapor jackets are very transient and the bubbles would break down and be replaced by the liquid quenchant as fast as they form. That amount of time is not as fast as the formation of martensite. The more likely conditions that could be affected by martensite formation are the changes occuring in the grain structure as a result of the transition from austenite to martensite or pearlite. Those could easily be affected within the amount of time available and could contribute to warping. Another likely condition is that the steel is still in the metastable phase and has not completed conversion to martensite and is "more plastic" than hard yet. In that state banging off the inside of the tank or possibly even the resistance to motion afforded by a thick cold oil could bend the blade against the resistance of motion provided by your hand. It wouldn't be the motion itself, or the vapor jacket, but specific conditions in the steel though. I admit, it's a lot easier to think that it's the vapor jacket.

The speed of the quench is important in establishing the desired crystalline structure in the blade. It is the crystal's size caused by heat treatment or mechanical deformation that causes the internal stresses, not because the edge hardens quicker. For that matter, the sword blade is under a tension stress because of the size reduction of the blade's spine to pearlite from the larger austenitic crystal.

I have a book on making samurai swords and they talk about using heated copper blocks to change the curvature of the swords if it has to much or to little curvature. Heating the sides of the blades with the copper then laying it flat on the anvil and giving it a whack with a wooden mallet to straighten the blades, etc...
For sheetmetal and bodywork I've seen old timer heat the side of car panel up and mist water on the steel to cause it to shrink and straighten out some creases.
So depending on the steel type used and application will determine what is best for straightening a blade, or just throwing it away.

You were okay up to the point of whacking it with a wooden mallet. The copper block treatment is to relieve the sori, the formal curve that makes it a Japanese sword. That technique is not used to straighten a warped blade. I've seen 1/2 steel plate straightened with a rosebud torch and a little hammer. Good smiths have good techniques, but not all of them work in all conditions.

And not everything people think they know is true, even when it works. I'm still learning all the time.

Berticus has a better idea than throwing away the steel.