first blade (straight razor)

[glyph250]

Well, here it is. I'm very happy with the overall shape, and with the lessons I learned the hard way about grinding with my bench grinder (1. wear gloves with thin work; 2. keep water nearby; 3. EDGE UP).

Only one problem mars its functionality--when I either hardened or tempered this blade, it curved the edge a tiny bit. The spine is still okay, for the most part. You can see it if you look closely at the picture I'm attaching. I wouldn't care if it weren't meant to be rubbed all over somebody's face, but it is. Can this be remedied, or should I scrap the blade and try again?

Thanks!

**Edit: I should add that the major reason I'm even bothering to fix this is that I don't want anybody pointing out that my straight razor isn't straight enough.

Edited November 24, 2009 by glyph250

[pkrankow]

If there is enough material and you are bothered so much why not straighten, normalize a few times and re-heat treat?
Phil

[glyph250]

I don't know how much material is enough material. Do you have a rule of thumb for this? And do you mean I should straighten it cold or hot?

[pkrankow]

First, I am not a knifemaker. I am not even very skilled as a smith, but am learning.

I would consider straightening hot, normalizing a few times, and then re-heat treating, AS OPPOSED TO THROWING AWAY THE BLADE. I am not sure how much material is enough material either. Before original heat treat I have read having about 1/16 inch of material is recommended so decarb is ground away and warping is limited

I was even looking at the enlarged pic, I don't see the bend you are talking about. I looked again at the pics too. Is the slight change in shadow the only visible artifact of the warp? How far out of line is it? Is the edge itself straight?

I'm not sure I would mess with it. I also have not examined very many straight razors. If you deem the edge too thin to tolerate another round of heat treat AND you are overly upset with the final shape due to deforming in heat treat, this may be a good candidate for destructive testing. There are guidelines for testing to be a journeyman blademaker.
JS Test

Maybe you need other opinions to be weighed in on this. Some additional pics may help some too.

Phil

[Rich Hale]

When I heat treat blades I leave material on the edge to help them not warp. Think about the thickness of a dime. Finish grinding and polishing after heat treat..if it warps you need to normalize and redo the heat treat. It will be tough to fix this blade. However since it is already bad give it a try,,,,,And a good thought to not let anyone see a blade yoiu made with a problem..you have the right attitude.

[son_of_bluegrass]

I don't see what steel was used. That may make a difference.

I wouldn't recommend trying to bend it cold. If you left it at the typical hardness for a razor, it will probably snap trying to straighten it.

You may be able to grind it out. I'd have to see it in person to know.

Most steels I use I can be heat treated a few times with no ill effects if the edge is thick enough. I've had some success with edges around 25 thousandths thick but not thinner. I generally shoot for 40 thousandths for heat treat.

If you think it needs to be scrapped then go ahead and try again, you're only losing the time anf fuel it takes to re-heat treat. If you start completely over, you'll spend more time and energy than if it works.

ron

[BIGGUNDOCTOR]

I am a little concerned about the statement of wearing gloves. When I was going through my machinist training we were told to NEVER wear gloves around rotating equipment-ever. If they get caught it could mean some serious damage to you. If it gets too hot to hold, that is what the water is for.


I would look into drawing as much hardness (tempering) as I could, straighten, and reheat treat. If you have access to stainless foil for heat treating you could wrap it to minimize scaling, or use a flux to coat it, and anneal.

[glyph250]

So many great posts! I've learned a lot from all of your comments.

Let me revise point one, on the advice of BIGGUNDOCTOR, to read: Make quick passes on thin work. BIGGUNDOCTOR, I never did get around to wearing gloves when working my grinder. It might have saved me a digit. For others reading this thread, I'd like to point out that since only one slow pass on a coarse wheel (albeit a slow one) left a burn on my right thumb, it's important not to make slow passes. FTR, a fine wheel had the same effect.

@pkrankow: Good idea regarding the destruction testing. Making a second one won't be as challenging as the first, both because of the experience I gained and because...

@son_of_bluegrass: I put a lot of work into stretching 2 inches of automobile coil spring with a 1/2 inch diameter into this blade. I estimate it to be 1085 from spark testing and reading. Hard enough to hold up at least a half ton of metal in its original job, at any rate. It turned out to be not enough to make a great straight razor, but just enough (after a lot of work) to make a straight razor-shaped object (SRSO).

@Rich_Hale: I was just under a dime's thickness when heat-treating this blade. It might have curved due to my inexperience when it comes to heat treatment (just a few punches and other tools), or it's just now occurred to me that it might have been a grinding error. I need a belt grinder, or at least a lot more experience with long pieces on a bench grinder.

Thanks for all the great advice. And if there's any more, please don't hesitate to post!

Edited November 24, 2009 by glyph250

[nonjic]

I would use it for sharpening practice, then crack on and make another!

You will be suprised at how quickly you forge the next one.

If you only have a bench grinder I would forge the edge to about 3mm thick, then knock the forging bark off with the bench grinder, then draw file it flat, then sand it flat (leave the edge approx 1mm thick (as recomended by others)

Once you have forged it and filed it heat evenly it untill a magnet doesnt stick to it, and let it cool completly in still air, repeat a couple of times (this is normalising, and reduces the size of the grains in the steel, and helps prevent warping when you heat to above non magnetic and quench in the warmed oil)

Temper the blade immediatly after quenching (a couple of hundred deg c in a domestic oven should be fine), or give it a very quick sand to get the oil sludge off and give a shiny surface, heat a bar of steel red hot in the forge and then hold the back (spine) of the blade against the hot bar, remove it when you see the edge of the blade turn an even straw colour. I then dunk it into water straight away or the edge will keep getting hotter from the spine of the blade and be to soft.

lots to learn, the best way is to keep having a go at it! :D

[bigfootnampa]

I don't think your steel is the problem. I just made a huge skewed gouge from an old mower blade and it will shave you easily (that's how I test for sharpness... the back of my left hand often has bald spots). I doubt that my steel is much higher carbon than yours. I think you ought to try some file steel though if what you want is a real quality working razor. Sharpening is not easy to do when you want real razor sharpness. I think you'll need a buffing wheel and some white diamond compound to finish the edge. You can shave hair with my axes when I have just finished sharpening them but they are awkward to maneuver and don't hold that kind of edge as well as a razor should. "Sharp" tools will just shave a little hair and "really sharp" ones will POP the hair off but "razor sharp" ones will effortlessly create bald spots.

[glyph250]

@John N: The process you described is exactly what I did, except I quenched in oil after the temper. Would that make a difference? It seems to me that it would make it less likely to warp that way, not more, but I'm no expert. That said, the part that was thinner was the part that warped, so a lot of you guys could be right about edge thickness.

@bigfootnampa: My process for sharpening blades is a little different. I use a wetstone (dry) to put a sharp edge on it, and then I use 1500 grit sandpaper in lieu of a strop to get that razor sharp edge. This is what I do with the straight razor I already own, as well as all my pocket and camping knives. It works pretty well--well enough for me to shave with, anyway.

Thanks again for your comments, guys.

[FLYBYU44]

First off I'm a total newbie on here, so I can't comment to much on the heat treating other then you should probably be grinding it after heat treating, not before. The edge was likely too thin to handle the heat without warping. I do know quite a bit about straight razors however, I regularly shave with one and have restored several before. First of all you generally need a pretty straight edge and spine. You have to be able to evenly hone the entire edge with the spine resting on the hone. The way it is right now, half the edge would be to shaving sharpness and the other half would be very dull. You have to have the right angle between the edge and the spine so that when you hone it you have a small included angle at the edge. It's nothing like a knife, I can get a knife to shave off arm hairs, even standing arm hairs, like nothing, but it still won't shave my face. You have to hone it with at least an 8000 grit stone and then strop it until the edge is perfectly polished.

[JamesBBrauer]

Just as a side note, you might want to check out the forums over at badgerandblade.com . They have a straight razor section, and really good shaving advice.