Thread: Blade straightening 101 (with heat)

http://straightrazorpalace.com/video...tml#post959449

(Thanks Charlie)

Please NOTE the difference is in the wording here,,,

For razor restroration, the issue is the Off center TANGS, so that the razor closes onto the scales.. we are not talking about straightening Blades

PICS:





This a razor that has a offset tang, note the dime and the difference between the two pics.. The issue is NOT the blade but the tang..

If you try and bend the blade portion it will probably break the razor, if you were to just straighten the Tang you might pull that off

Now just to be perfectly clear, I didn't bend anything to make this razor close centered I simply adjusted the scales

Originally Posted by gssixgun

(Thanks Charlie)

Please NOTE the difference is in the wording here,,,

For razor restroration, the issue is the Off center TANGS, so that the razor closes onto the scales.. we are not talking about straightening Blades

PICS:





This a razor that has a offset tang, note the dime and the difference between the two pics.. The issue is NOT the blade but the tang..

If you try and bend the blade portion it will probably break the razor, if you were to just straighten the Tang you might pull that off

Now just to be perfectly clear, I didn't bend anything to make this razor close centered I simply adjusted the scales

Glen,
This is almost EXACTLY like the blade I was TRYING to straighten. Mine was FLAT on one side and about twice as high on the other.
Guess I should have researched more...

Ed

Originally Posted by Chevhead

Glen,
This is almost EXACTLY like the blade I was TRYING to straighten. Mine was FLAT on one side and about twice as high on the other.
Guess I should have researched more...

Ed

My PM box is never full hehehehe ok sometimes it really is

Also we are starting up the Restore Chats on Tuesdays at 8pm EST in the Chat room

So if you have questions please ask...

Originally Posted by PierreR

...Thanks for questioning me. I will continue to answer if I can. If I can't please answer me when I ask a question.

Mark Twain said that "An expert is any man that can spit over a boxcar." I have a long way to go myself.

Originally Posted by Chevhead

Glen,
This is almost EXACTLY like the blade I was TRYING to straighten. Mine was FLAT on one side and about twice as high on the other.
Guess I should have researched more...

Ed

yes definitely.
That same issue of braking razors while trying to straighten the tang has come up before.

So far Charlie has the best method that I know of, although I personally am no longer trying to fix bent tangs.

I have been a knife maker for many years. I started in the seventies. Back then guys like Bill Moran and Bob Loveless were the kings. The knife makers of today owe a lot of what they know to the mistakes these guys made both in making knives and attempting to straightening them. I am sure they broke a lot of them. I know I broke some. But how the heck do you learn anything unless someone is willing to try. If something didn't work they passed the info on and someone eventually figured out how to do it by their mistakes. Some of them probably tried things out for the first time on a very expensive piece and I'm sure some of them said " I will not try that again!" Others did try again! That is just how we learn. Sad as it is.

We all make mistakes. And I do make a fair share of them. More than Mike or Pierre probably, simply because they are quite a bit more knowlegable than I am, for example.

When we share a technique, we usually indicate the details surrounding the technique, such as success rate and grind type (or whatever is applicable of course), so that anyone using the technique knows the context of its use and is able to decide whether they match or not. When straightening a tang it is relatively easy to separate the tang from the blade. When straightening a spine, that is more troublesome and it becomes greatly important a) with what grinds this was attempted, and b) what the success rate was. What might work on a wedge might not work for a hollow ground.

An additional issue with razors is that the hardness of the spine is (almost) as important as the hardness of the edge. A softer spine will lead to additiona hone wear. And if the hardness is not even, the honewear might develop assymmetrically.

We learn from mistakes, but we can also learn from other people's mistakes, which is why I've also posted in the past how not to do certain things . and for that to work, we need to post the details of what we tried in which circumstances, that wasy we can learn from new mistakes (expanding the total sum of knowledge) rather than using a specific technique and making the same mistakes that the last person made. By avoiding the same mistakes, both the person and the community learns faster.

Will a blade straighten if you simply put it in the vise and tension it and leave it for a week?

Originally Posted by eod7

Will a blade straighten if you simply put it in the vise and tension it and leave it for a week?

Not generally. They require a counter force to correct the bend.

Bruno's point is a good one. Learning from mistakes is critical. That means you will break blades. I have broken more blades deliberately because I wanted to test the processes involved than I have accidentally. Usually the accident produced a learning curve solved by breaking more blades. And, I'm fairly fearless about breaking things. It does represent hard work lost to the scrap heap versus knowledge gained. I cannot balance that equation for every maker. I only can tell you what I've learned from what I've done and from other makers have told me about their mistakes.

Originally Posted by eod7

Will a blade straighten if you simply put it in the vise and tension it and leave it for a week?

Unlikely. First of all, as Mike said, you'd need to counter the bend. This means clamping it in such a way that you bend it the other way. Just straightening it is not enough. The reason is that any deformation is part plastic, and part elastic. The plastic part is permanent, but the elastic part will always return. So if you clamp it straight, the elastic deformation would always return and you'd still have a bent blade. You'd have to bend it far enough the other way, so that the plastic deformation minus the elastic deformation would come out exactly in the position where the blade is straight.

I've done this a couple of times, and also broke a couple of blades. I only do this with my own blades (ones I make myself) because if it breaks, I haven't broken anyone elses blade.

Now, if the spin of the razor is through hardened, there is zero chance of straightening it by cold bending. A hardened piece of steel is essentially a spring. It has no material for plastic (permanent) deformation. Like a car spring, you could clamp it and leave it for weeks, and it would return to the exact same position.

If there is some unhardened or partially hardened steel left, you have a margin for correction. But that is less than you might think. I tried this on a differentially hardened (like a Japanese sword) kitchen knife.it had a small kink in the middle. And rather than bothering with annealing, straightening, claying and heat treatment again, I tried cold bending it, figuring the 'softer' spine would give me some leeway. It did, but not enough. And when I tried to push harder, it just snapped.

This is where you would need to hot bend, like Pierre explained. Because then any correction would be plastic instead of elastic. However, for knives this works different. Because knives have a lot of thermal mass and don't heat up that quickly. So you can control the spread of heat fairly well, and it goes slow enough that you can work. For a razor which is a big wedge, this might work as well.

For hollow or medium ground razors, it would be very tricky. If you take a lump of solid wood and try to light it with a propane torch, you need a bit of time because the lump of wood has a big thermal mass and needs some time to heat up. And the non-heated part acts as a heat sink. However, any splinters or wood 'fluff' sticking out will be incinerated immediately, even if they're not hit directly by the flame. This is because they have virtually no thermal mass.

For a hollow ground razor, it is the same. You put a blowtorch on the spine, but the spine takes some time to heat properly. the edge however is paperthin, and will heat up almost instantly. The risk of overheating the edge is very high. And then there is the problem with clamping. If you clamp the razor, the edge becomes inaccessible, so if you need to pour on water, it is not a given that the water will reach the edge in time, or at all. There are some technical difficulties which are far less important with knives.

This is why, when translating a knife technique to a razor, we like to know in which circumstances it was tested, and what the outcome was. Suppose (for example) this technique would not work with hollow ground razors at all, but it would have a 90% success rate with full wedges and a 50% success rate with half hollows. It would be an important bit of knowledge for anyone considering this. Otherwise, there is going to be a good amount of people who'd try it in circumstances where it was doomed ffrom the start.

This is what I meant by 'learning from other peoples mistakes'