knife maker making a razor

So what would be some tips for someone, who makes knives and has no experience making a razor, who wants to make a straight razor. I would probably first start out just doing stock removal for the first one or two and then go to forging. Its so much smaller than what I normally forge that I dont want to start out trying forging from the get go. For grinding I use a 8" bench grinder when I grind knives. Mainly whats the geometry requirements. Im not to good at doing maths and honestly dont remember my formulas from high school to figure out the geometry. I was thinking of using 3/16ths stock but I do have 1/4" also available. Using 01 for the steel. Thinking something like a french point and would like to have some smile to it.

The geometry is about 16ish degrees, or 3.5 or 4 in blade width to 1 in spine thickness.

Charlie

https://youtu.be/isPvvVdyQio

If your razor is 7/8 to 8/8 use the 1/4 thick stock

There are a ton of great links here to Youtube vids. I joined this board recently because I found myself here researching so much I figured what the heck. I am also a knife maker , and have developed an obsession with razors lately.

If you have a shop full of gear and can properly HT 01 its all about the design/layout and the grinds. As far as the small size and grinding goes, its a refreshing change no more difficult than any other hollow grinding just have to watch the heat a little closer because of the thin edge.

I am mid stroke on my first batch of six and so far so good, went with 1/4" x1" O1, and grinding on an 8" wheel, thread is below somewhere. I will get back to them later this week. Right now Im finishing a batch of kitchen knives which will finance two more tooling arms and smaller contact wheels for the KMG. Bit by the bug I was.

Awesome thanks guys. Oh yeah if using o1 would I still be going for a bout the same heat treat as I would knives or do I want a harder blade for a razor. My knives are typically around 56-58 HRc.

For razors you will want to aim a little higher. 59 to 61 is generally thought to be the sweet spot

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Originally Posted by Bruno

For razors you will want to aim a little higher. 59 to 61 is generally thought to be the sweet spot

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out of curiosity, since yo don't need any impact resistance, you could in theory just quench with no temper and get a super hard blade, especially if you are using 1095 or other high carbon. I've been shaving with a straight for years but just a beginner in the honing arena, so I don't know if it will effect that other than taking a bit longer to set the bevel, but will a super hard but brittle razor have any drawbacks?

In my experience I get a smoother/more comfortable edge on a tempered blade.

I am not exactly sure why, but I would surmise that the tempered blade edge is a little more resistant to crumbling at the very edge and takes and keeps a better edge.

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Originally Posted by Boots

out of curiosity, since yo don't need any impact resistance, you could in theory just quench with no temper and get a super hard blade, especially if you are using 1095 or other high carbon. I've been shaving with a straight for years but just a beginner in the honing arena, so I don't know if it will effect that other than taking a bit longer to set the bevel, but will a super hard but brittle razor have any drawbacks?

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Negative, any blade must be tempered to some degree after the quench. A 1095 blade can crack just sitting on the bench if you dilly dally between the quench and temper. You can adjust the HRc (RC) by adjusting the temper temperature.

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Originally Posted by spazola

In my experience I get a smoother/more comfortable edge on a tempered blade.

I am not exactly sure why, but I would surmise that the tempered blade edge is a little more resistant to crumbling at the very edge and takes and keeps a better edge.

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They are all tempered, weather a manufacturer uses that as a marketing gimmick or not.

Something very common in the SR world is confusion, or misinformation about tempering/HT of steels. I have watched several videos now being narrated by someone in the SR community at a makers shop describing the HT process and he was way off in his interpretation of what goes on. Not a big deal as far as consumers go , but if you were researching processes (me) that is bad info.


EDIT
***** the saying "don't tell fish stories to the fish" comes to my mind here. Hahaa don't think I need to explain HT to you.
Im leaving my answer up for you to educate me here if I am wrong. Just saw your avatar after I replied and thought it looked familiar from the videos.

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Originally Posted by AKmik

They are all tempered, weather a manufacturer uses that as a marketing gimmick or not.

Something very common in the SR world is confusion, or misinformation about tempering/HT of steels. I have watched several videos now being narrated by someone in the SR community at a makers shop describing the HT process and he was way off in his interpretation of what goes on. Not a big deal as far as consumers go , but if you were researching processes (me) that is bad info.


EDIT
***** the saying "don't tell fish stories to the fish" comes to my mind here. Hahaa don't think I need to explain HT to you.
Im leaving my answer up for you to educate me here if I am wrong. Just saw your avatar after I replied and thought it looked familiar from the videos.

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I am not sure what to say, I speak in the videos, as I understand the process. I feel pretty comfortable with my heat treating process and knowledge.

I am not sure where I am way off in my understanding of things, my thoughts and processes agree with the text that I have read, and the knowledge that has been passed on to me by other more knowledgeable teachers.

Life long learning is one of my core principles, teach me.

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Originally Posted by AKmik

Negative, any blade must be tempered to some degree after the quench. A 1095 blade can crack just sitting on the bench if you dilly dally between the quench and temper. You can adjust the HRc (RC) by adjusting the temper temperature.

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That's awesome! thanks for engaging in my hypothetical.

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Originally Posted by spazola

I am not sure what to say, I speak in the videos, as I understand the process. I feel pretty comfortable with my heat treating process and knowledge.

I am not sure where I am way off in my understanding of things, my thoughts and processes agree with the text that I have read, and the knowledge that has been passed on to me by other more knowledgeable teachers.

Life long learning is one of my core principles, teach me.

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Oh , No sorry.

Let me clarify here, not your videos I was referring to. I was not in any way criticizing your work, or videos. This was one made by what sounded like a person from a shave shop, who was did not really understand the heat treat process.

I have been learning from watching you my man. I have been making knives for about 15 or so years, but am very new to making razors. I have been watching your videos and any other out there for the last couple months and reading up here on the board, actually what brought me to SRP. I just started my first batch a couple weeks ago.

What i was saying is that all blades (carbon steels) go from the heat treat oven/forge to the quench , and then are tempered as the final step in the HT process.

I was confused by your post stating that you found tempered razors more comfortable, since as far as I know all steel needs to be tempered after heat treat...

It's hard to debate when generalities are being discussed. AKmik, perhaps speaking of more specific points will help this discussion.

Charlie makes good razors. I know the sources of his heat treatment education. Those are difficult to criticize. But, his razors shave hair, and his customers are satisfied. He meets the first major criteria successfully. Throughout history there have been a lot of blades that were good blades that did not benefit from the HT knowledge we have available today. They are no less good than what we make now.

I have noticed that some schools do not separate heat treatment, e.g. heat and quench to harden, from tempering, e.g. heat to reduce hardness or stress relief, but call the whole process tempering. This is imprecise but difficult to correct in common use.

edited to clarify things.

it's true that even many knifemakers on youtube spout nonsense. I've heard one explain that quenching puts extra carbon in the steel and that's why it is hard.

In any case, while a no-temper hardness is of course harder, the edge will also be prone to microchipping and be difficult to hone because of that. So aside from the fact that microchipping will degrade shaving quality, honing is part of the normal lifecycle of a razor and if honing becomes very finicky, that hurts the usefulness of the razor.

Hence the sweetspot of 59 to 61 which is very hard, has good edge retention, can be honed to a very sharp edge, and is easy enough to hone. Much higher and honing become a nuisance. Much lower and edge retention will suffer.

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Originally Posted by Mike Blue

It's hard to debate when generalities are being discussed. AKmik, perhaps speaking of more specific points will help this discussion.

Charlie makes good razors. I know the sources of his heat treatment education. Those are difficult to criticize. But, his razors shave hair, and his customers are satisfied. He meets the first major criteria successfully. Throughout history there have been a lot of blades that were good blades that did not benefit from the HT knowledge we have available today. They are no less good than what we make now.

I have noticed that some schools do not separate heat treatment, e.g. heat and quench to harden, from tempering, e.g. heat to reduce hardness or stress relief, but call the whole process tempering. This is imprecise but difficult to correct in common use.

edited to clarify things.

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Mike,

I do want to be clear, I was not criticizing Charlie's work , not at all. He makes a great looking product and his videos are a joy to watch as another craftsman. I have learned a ton watching him work.

You are right , I think its just the wording and the conjoining of the process that had me questioning. hahaa then of course I felt like an ass for questioning the guy who has been showing me how to make razors , but Im good like that.

Bruno,
Absolutely, Lots of bad information floating around on different blade forums and youtube. 59-61 is the sweet spot which requires tempering to achieve, so I believe we are all on the same page.










So

I feel like we need one of those, nothing to see here, lets move along post.

Move along. please.

sooo just to add another hypothetical metallurgical question, because I rarely (see never) have access to people with so much HT and temper experience, what about using 5160? according to the specs its quenched hardness is around 58-62, meaning quenched it would have exactly the right hardness for a razor, and due to the lower carbon content (spring steel ftw) it would keep a more malleable quality. thoughts?

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Originally Posted by Boots

sooo just to add another hypothetical metallurgical question, because I rarely (see never) have access to people with so much HT and temper experience, what about using 5160? according to the specs its quenched hardness is around 58-62, meaning quenched it would have exactly the right hardness for a razor, and due to the lower carbon content (spring steel ftw) it would keep a more malleable quality. thoughts?

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5160 can get hard enough, but hardness is not everything. The greater amount of carbon in a high carbon steel makes for a more abrasion resistant steel.

I have not made a razor from 5160, but I do not think it would hold an edge as long as a higher carbon steel like O1, or 1095.

Hardness is only one consideration, grain size, and abrasion resistance are also big players in consideration of steel for a razor.

@Boots:

As Mike Blue said above, tempering is not just to reduce hardness/increase toughness, it is also done to relieve stress in the hardened steel.

Quenching is very hard on the structure of the steel, relieving that stress means the blade won’t decide to crack whilst just sitting on the bench or when lightly knocked against something.

If using steel in its fully hardened state was a good idea, it would have been done before and the reams of writing on the process of tempering to get the desired (or at least useful) properties could have been saved.

5160 will meet the hardness criteria. Where that steel excels is in toughness. That explains it's strong use in spring applications. The only way to know for sure is make a razor out of it and shave with it. The biggest problem I have with spring steels is that you can't guarantee that old auto/truck springs are the steel you think it is. Given time and tools, making a razor and testing it will tell you a lot.

It's really easier, potentially a lot less heartbreak, to buy a bar of known steel and keep things simple.

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Originally Posted by DrDalton

If using steel in its fully hardened state was a good idea, it would have been done before and the reams of writing on the process of tempering to get the desired (or at least useful) properties could have been saved.

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As you say, reams of writing, on the subject, and there is just as much misinformation of not more. I'll probably never know as much as some of you guys have forgotten on the subject of HT. Like it or not, this forum is one of the few reliable resources out there, and I appreciate you sharing your knowledge. I know my incessant questions can be annoying, but I don't know anything about making razors, that's why I'm asking the pros.

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Originally Posted by Mike Blue

5160 will meet the hardness criteria. Where that steel excels is in toughness. That explains it's strong use in spring applications. The only way to know for sure is make a razor out of it and shave with it. The biggest problem I have with spring steels is that you can't guarantee that old auto/truck springs are the steel you think it is. Given time and tools, making a razor and testing it will tell you a lot.

It's really easier, potentially a lot less heartbreak, to buy a bar of known steel and keep things simple.

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I couldn't agree more, buy a known steel. I didn't mean to imply I was doing otherwise. 5160 is my favorite for larger blades because it's tough and the temper is very forgiving. I don't have any fancy equipment like a kiln so forgiving is important with sub-standard tools.

there is an additional consideration which I've meantioned a couple of times in the past: razors don't need toughness. At all. Only edge retention, a fine edge, and a decent hardness. That means that additional toughness doesn't add any quality to the razor, but it does make grinding and sanding a lot more difficult and annoying than it should be.

52100 for example is excellent stuff and I have made kitchen knives from it. For razors is doesn't give an edge that is better than O2 (which is my favorite tool steel) but it makes grinding and subsequent sanding at least twice as difficult and time consuming.

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Originally Posted by Mike Blue

5160 will meet the hardness criteria. Where that steel excels is in toughness. That explains it's strong use in spring applications. The only way to know for sure is make a razor out of it and shave with it. The biggest problem I have with spring steels is that you can't guarantee that old auto/truck springs are the steel you think it is. Given time and tools, making a razor and testing it will tell you a lot.

It's really easier, potentially a lot less heartbreak, to buy a bar of known steel and keep things simple.

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No doubt about it there, salvaged steels are not for me. Lucky for us we have the world at our fingertips these days and about any quality blade steel is available. The fear of that "heartbreak" you speak of has kept me from using salvaged steel, Id hate to get to the final edge on a finished project and find that a mistake in material was made. the horror hahaa


If one wanted to use 5160 it is easily obtainable in bar stock from the NJ steel Barron.

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52100 for example is excellent stuff and I have made kitchen knives from it. For razors is doesn't give an edge that is better than O2 (which is my favorite tool steel) but it makes grinding and subsequent sanding at least twice as difficult and time consuming.

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That's good to know, I'm working on my first razor from 52100. So far I haven't noticed any issues grinding it, but then I'm used to forging and grinding 52100, we'll see when finished if it's worth the extra effort of forging it and heat treating or to simply try 80CRV2 next go round, or even just plain 1084. I don't have any 1095 on hand.

I think 5160 would make a decent razor, but I don't know if it would be enough of a difference between other steels, only way to know would be to test them out. The thing about 5160 is that it's a little low on carbon, but the chromium content aids in hardening so you can get a blade in the 59-61 RC range while maintaining chip resistance. Also, from my understanding, it's the carbides that do the cutting, and chromium carbides are tougher than carbon carbides. 5160 properly heat treated will have very small grain size as well which lends itself to a very fine edge, but 1095 will be slightly finer, if not quite the edge holding, so the only real way to know is make two and test side by side. This is all theory when applied to razors though. For the best 5160 I've ever used see if you can get a John Deere load control shaft, it's 5160 that is held to JD's specs which are a lot tighter than the nominal steel industry standards.

As for the original poster, I'm in the same boat, having to learn to look at things differently from knives and there is a learning curve I'm slowly climbing. A straight razor is surprisingly complex for a simple sharpened bar of steel, but then the same can be said of knives.