Thread: Blade straightening 101 (with heat)

thats the same post i read the other day and decided i was better off just reading it and sticking to my rooolllllliiiinnnnggg strokes on the hone ...lol

I believe there are certain workshop posts that should be stickied ... This is one of them. Bravo for the well written report!

Originally Posted by straightrazorheaven

I believe there are certain workshop posts that should be stickied ... This is one of them. Bravo for the well written report!

Here here, I would second that.

hmmmmm sounds familiar !!! Great write up and love the pictures.

Have you done hardness tested with razors, tested along the edge and spine. I'd like to see some test data because razors are much thinner than knives. Especially with hollow ground razors, it would be good to have test data before someone actually tries this on a razor. Before the spine is hot enough to bend, a lot of heat has gone into the edge.

I also wonder: how do you clamp the razor in the vise?
Edge up, and you'll make the edge part much hotter than the spine part (because the vise acts as a heat sink.
Edge down, and pouring water will have trouble reaching the edge because the vise is in the way.

The edge can be extremely thin, which is why I'd like to know if this has been tested on razors, and if so, on which grind types

IIRC Charlie aka Spazola also has this system up here on SRP too, I will seach for it and see if I can't link the two...


It works -BUT- it should be used as a last resort fix.. I always worry when these advanced techniques are posted because people start using them when they are not needed...

To give an idea I have used the Vise fix 3 times total out of all the razors I have restored...

The heat used isn't high enough for long enough to do an actual "heat bend" the tang isn't getting anywhere near red (which is what people think of when heat bending steel)

As for razors being thinner than knives, true on the edge, but on the spine? I straightened a cleaver yesterday that was 0.95" on the spine and .010 behind the edge. I also did a fillet knife that was 0.060 on the spine and where the blade was only 0.38" tall. So as far as the amount of steel being manipulated, the fillet knife is quite thin.

Clamping the razor would depend on where the bend is, and where the heat needs to be placed. If the spine is bent, spine up, if the edge is bent, edge up.

I have straightened my own blades for about 7 years... alot of them. I learned from 2 knife makers who have done it for over 40 years each. It works. One of the two is a retired metallurgist, who prototyped and heat treated engine components in the aerospace industry, and now makes some of the most beautiful knives out there, and is a mentor to many.

Testing? Rockwell testing on knives numerous times. In worst case scenarios tests I have seen/done were as expected, in relation to color change on the blade. From no change (within the margin of error of the equipment) to a drop of 1.5 to 3 points if the heat applied changed the blade color into purples/blues.

Tested on razors? I have not aligned many razors. Scientifically tested one, prior to being final ground. Edge thickness was .01, and because of the shape of the blade, it was difficult to set it in the machine correctly. I have not straightened a full hollow ground blade on the edge, but have on the spine. No I didn't test that one. Why? a couple reasons. A Rockwell tester achieves its data by measuring the depth a hard point is pushed into, or rather the amount the test media resists the point being pushed into it. Nobody wants a dent on their mirror finished blade, and in all likelihood it would crack a blade so thin. I have yet bought a razor blade to sacrifice to destructive testing.

At the end of the day, all I can tell you is it works. Is it without risk? No. Is it worth the risk? Thats up to the individual. Is it fool proof? No. Steel is steel. The effects of heat on steel are recorded, repeatable, and quantifiable. Be it 1 inch thick or .001" thick. the difference would only be the amount of heat over a given time. As I said, the heat we are dealing with is for seconds, over as broad an area as needed. As I clearly stated, watching for the color change you have control, and choice. Again, we are not relying on heat to soften the metal to make the bend as in traditional forging techniques, but warming the blade to within the tempering range to reduce stress. It is less risky, and more reliable then a cold 3 pin bend, or God forbid, pliers or a pipe!

If I had a bent blade that was 200 years old, and of collectors value would I attempt to straighten it? If it was for a collection, no. If I didn't care about its history other than wanting to shave with a 200 year old blade? I would, you might not. I am not telling any body to do it. I am not telling anybody it is foolproof. I am telling you it can be done, how to do it, and what to watch out for. Some comments made in this thread have a skeptical tone to them. Fair enough. Don't do it then. For the gentleman who snapped his blade, the reason I wanted to post this, would it have helped? Hell yeah! Would it have worked? I did not see the initial bend, but yes it could have worked. Would the blade still broke? Possibly. Would he be worse off if he tried and failed? Nope. Would he be happier if it worked? I don't know, ask him.

I'm new here. You don't know me from a hole in the ground. I have a machinist background, and still work with blades on a daily basis. I wouldn't take the time to write all that I have if it didn't work. Listen it was posted earlier and scoffed at. If you are going to attempt to straighten a blade and it works for you, its worth it isn't it? Have I broken blades? Yes. 3 in 7 years. How many have I straightened? I would guestimate near 80 that I have made, and less than 20 for others. I lose more blades in the HT and quench, then from straightening.

I hope this helps.

Pierre

Originally Posted by PierreR

The heat used isn't high enough for long enough to do an actual "heat bend" ...

As for razors being thinner than knives, true on the edge...

I have straightened my own blades for about 7 years... alot of them.

Testing? Rockwell testing on knives numerous times. ...

Tested on razors? I have not aligned many razors. ... Nobody wants a dent on their mirror finished blade, and in all likelihood it would crack a blade so thin. I have yet bought a razor blade to sacrifice to destructive testing.

At the end of the day, all I can tell you is it works. Is it without risk? No. Is it worth the risk? Thats up to the individual. Is it fool proof? No. ...

I'm new here. ... I lose more blades in the HT and quench, then from straightening.

Pierre,

I find no fault with your desire to share. I have 27 years in making blades of all kinds, and 5 or 6 years of learning about making razors and I am not yet personally ready to start producing razors with any great frequency. In fact, it was 27 years ago that I learned this method from Bob Engnath, one of the very great knifemakers in the US at the time.

Glen has noted that there are many people here who could be tempted to try this method, and without your level of experience and they will fail. This is no different than introducing a cultural change when the previous culture is not ready to accept it. Failure results, and the natural consequence will be to blame the one who introduced the change.

I have Rockwell tested razors and that little dent is not some mark of a defect. On this we disagree. Razors do not Rockwell test like a knife will, without knowing this your knowledge will remain limited. Yes, that little diamond point can create problems, but a lot can be learned as a result as one of the members here recently discovered.

Your assumption about the steel content of razors being near enough to 1095 to not make any difference is not correct. This site contains some interesting data about that for those who are willing to dig a little deeper.

That you lose more blades in HT and quench is concerning to me, given your represented experience. This makes me want to criticize the "old boys" who made all those great razors that did make it into the marketplace with residual warping. However, they did not know what heat treaters know now back then. It's not their fault. People shaved with warped razors for a lot longer than you and I have been alive. It was okay then, and is probably best to just let it be now. The Honers have figured out how to compensate for what was considered a normal, or at least acceptable, feature before folks like you and I came along to say warps were somehow bad things. There are a lot of warped razors out there providing journeyman shaving service every day. The owners think no less of them than their finest razors. Understanding HT is critical, and if understood to its greatest potential, does help understand why blades warp in the first place, and provides a means to prevent it.

Knives are not razors. Begin with that thought, stick with it and keep an open mind about what the folks here have to show you. Too many good knifemakers have been here, and gone because what they knew got in the way of what they could know.

Thanks Mike. You are correct. Knives are not razors, I concede, razors are a different animal. Out of context, me saying I have broken more blades heat treating sounds bad. I can count those blades on 1 hand. I broke 3 straightening, an had 5 fail in HT caused by stress points not addressed prior to HT'ing. I am not an expert by no means, and in my attempt to help may have opened up a whole different can of worms. I may not have many as years under my belt as you or likely many others on this or other boards, true enough. I do intend to change that, but time being what it is... well only time will tell.

I also didn't say the test mark was a defect, i said nobody wants a dent on a mirror finish. I also understand that razors and knives test differently. I also freely admit I have a LOT to learn. No contest.

Nor did I say "the steel content of razors being near enough to 1095 to not make any difference" I said "This is a steel still used today in modern razors, and I suspect very near in composition to razor steel of old." I merely used the numbers as an example.

Mike I concede. I am not trying to argue, I make no secret of the fact I don't know razors, or everything about knives. That why I am here, this is why I ask questions of moderators, and mentors. I have an open mind, and spend a lot of time reading, and testing what I have read. I am only now getting into razors, both using and making. I'm green. I have a lot to learn, but can offer aid as well.

Some people are happy with a warped blade, some are not. Some will leave things lie, some will try to correct them. Some will succeed, some will fail. I provided a method that works. All the time? No.
Guys don't hold it against me, or judge me because I offer. I plan to hang around, ask questions and learn. Open mind? Yup, got a big one. My wife figures thats all that up there... openness. Again, I'm not arguing, or saying its infallible. Its not for everyone, and wont work 100% of the time. But it works for me and some others more than it fails.

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

Originally Posted by PierreR

For the gentleman who snapped his blade, the reason I wanted to post this, would it have helped? Hell yeah! Would it have worked? I did not see the initial bend, but yes it could have worked. Would the blade still broke? Possibly. Would he be worse off if he tried and failed? Nope. Would he be happier if it worked? I don't know, ask him.
Pierre

I would have been MUCH HAPPIER if this worked.
Of course I have changed my mind on "bending/straightening" a razor now. I will NEVER EVER...EVER do it!
I will adjust the scales to make do so the blade closes in the center or as close to center as possible!
I in effect threw away a $400+ razor with my STUPIDITY. No pits,stains,corrosion.
I WISH I had it to do over again.
I would SLAP myself for even THINKING of straightening the blade....

Now if someone would want to try the only suggestion I would give them is:
1. Does it really need to be straightened?
2. Can you still get an edge on it?
3. If the answer is yes then....
4. Put the razor down!
5. If you NEED it to be straightened, SEND IT TO A SKILLED PERSON TO BE DONE FOR YOU!
6. If you still plan on doing this, make SURE you don't care if the razor gets ruined
7. If you are skilled (or lucky enough) to successfully do this AWESOME!
8. Take this for what it is worth, only my opinion, nothing more, nothing less
Ed

EDIT: I DID NOT USE THIS METHOD TO TRY AND STRAIGHTEN MY BLADE....