Razor making how to for smiths

[Bruno]

Folks at IforgeIron.com (IFI) asked me to write a razor making how to. I said yes, and since a customer requested work in progress pics, I decided to kill 2 birds with 1 stone. Sadly, IFI moved away from VBulletin, to something cheaper. They have been having catastrophical software problems ever since. Posting anything longer than a couple of paragraphs with some pics is subject to an endless slew of disappearing posts, random permission errors and timeouts, etc. I gave up after a couple of posts in that thread and a couple of people asked me to post it on my personal site.

I decided to post it here instead, because then there is a way to discuss things and answer questions. To the visitors from IFI: Welcome. If you want to know anything or everything about straight razors, you have come to the right place. Feel free to register and participate. I can promise you that you can write long posts and not lose a single one after clicking 'submit'.

[Bruno]

This is going to be an article on how to make a razor. There are many ways to go about this. Some people will do it differently. Some makers whose work I respect a lot work differently. This is just how I work, and it works for me.

At a high level, it goes something like this: I start with stock, and forge a razor blank to shape. I anneal it, grind / file it to shape, and do heat treatment. Then comes the finish grinding, polishing, and making scales. At that point it is ready for honing and test shaving.

During the process, I don’t use center lines, I don’t measure angles, and with a couple of specific exceptions, I don’t measure anything. It’s all eyeballing and ‘that looks about right’ engineering. In this article, I will work on the assumption that if you want to follow it, you already know basic forging, metal working and heat treatment.

I will use Damascus for this project. It should go without saying that you should work with materials that are suitable, and that you are confident in working. A razor can be a tricky thing to make correctly in terms of geometry. Before you move on to expensive materials, you will want to be confident in your skills, know how to recover from mistakes, and have enough experience to recognize the first signs that things are about to go pear shaped so that you can correct in time.

A good steel for razors should have enough carbon (0.7% or up), have a fine grain, and be free from many of the alloys used in knife steels. The only requirements for a razor steel are that it can take a fine edge and be honed by a human. A razors edge is not subject to shearing forces or impact. It does not need to be wear resistant. That means that 52100, M42, Hitachi blue steel, while excellent knife steels are not good choices for a razor.
They are extremely difficult to work, especially the post heat treatment grinding and polishing. They fight you every step of the way. When get to the honing stage, it will be a dog to hone because it is so wear resistant it is like whittling down your stones. And in the end, the edge will probably not be as fine as if you chose plain carbon steel.

Then there is oil vs water. A hollow ground razor can easily crack or warp during water quenching if the hollows on both sides are not identical. And even then, it may crack if it hardens differentially. And because of the thickness of the spine, that can happen. With oil that is usually far less an issue.
When it comes to regular steel, my preference is O2. It is in my opinion the best steel for a razor. It has .95% carbon, Manganese which makes it harden nicely, and nothing much else. It also produces edges that are fine, strong, smooth, and yet pretty easy to hone. It is not available in the US anymore, so we usually tell beginners to use O1 instead because it is a pretty good general purpose steel. The Tungsten makes it fight a bit harder than is ideal, but the heat treatment is straight forward, and quenching is safe.

In this case the Damascus I use is an O2/L6 mix which is made for me by Howard Clark. Howard makes it for me without precision grinding it. It would be pointless for him to precision grind it only for me to throw it in the fire and hit it with a hammer. It might look like precision ground stock in the pic, but that is only because he is just that good with a power hammer.



The first thing I do is grind the sides clean to double check there are no welding issues, and to grind away any evidence of the last fold. It’s been my experience that if you get rid of the lines that show the last time it was folded, the odds of it splitting when I hammer it are drastically reduced.

[MJC]

I'm signing up just to follow along...looking forward to this.

[Bruno]

Now it is time to forge out the general shape of the razor. I use a primitive setup to heat the steel. I like working with charcoal because it burns clean, doesn’t smell, and doesn’t have the potential to make the shop go boom.



First I mark the transition between the edge and the tang using the side of the anvil. Then I upset the tang area a bit to get it out of the way of the edge part. Then I do the same at the other end of the edge part, using my horn to pinch it just a bit. This makes it fairly easy to bevel the edge part into a triangle without messing up the tang. Once the edge part has been shaped, I further upset and draw out the tang into a taper.





The reason I do it in this manner is that I have found this to be the easiest method of making the blank while ensuring that the tang and the edge are aligned properly lengthwise while also keeping them aligned in the vertical plane. With this I mean that if you look head-on at the blank, you see the triangular section positioned vertically, with the crosscut of the tang behind it, also with a rectangular cross section oriented vertically.

I have found this to be the trickiest part of the process because where they meet, the steel develops ‘shoulders’. If you hammer the triangle once while the shoulders are on the anvil, the tang twists and realigning it is a bother. Additionally, the tang has to taper evenly from the shoulders to the end of the tail. I cut the blade from the stock using a cut-off hardy. With some steels I use an angle grinder. For example the Japanese suminagashi steel (white paper steel core with soft sides) has delaminated twice on me when using a cut-off hardy. Granted, that could be resolved by cutting hotter, but that creates the problem that the spine might bend sideways because it isn’t very strong when hot on account of the mild steel sides.

This is the final shape of the blank.



Experienced blacksmiths will probably remark on the fact that the tang still looks rather lumpy and not at all cleanly shaped. There are several reasons for this. Firstly, I don’t need to make the blank longer than the length of the razor. Drawing out more precisely will not help me get another razor out of the bar. So rather than draw it out further and cutting an inch of useless stock, I make it just long enough and allow myself the luxury of having some extra material to correct for minor misalignment.

Secondly, the design of this razor has several sharp notches in the tang. Forging these in the tang would be more difficult because hammering in one will move the one on the other side and it is easy to hammer too far.

And thirdly, in many cases I don’t yet know exactly what type of razor I am going to make. Whenever I am forging, I make a couple of blanks with a generic shape, to be used at a later date whenever I am playing with a design idea. Then I can just pick a blank from the box and start grinding. This is also in part because I forge outside, and weather conditions don’t always allow me to forge when I want to in the winter.

If you make a lot of razors, you will learn to recognize just how big the tang area needs to be to ‘fit’ the shape you have in mind. Sometimes I will forge the tang and blade to their exact shape, if the design is more fluid without sharp transitions in the tang. That does save time in the process because you only need to clean up the surface, but is of course also a bit trickier since there is very little room to correct alignment issues between the tang and blade.

So to summarize: if you look at the picture below, the part on the left side of the line has a triangular cross section, the part on the right has a rectangular cross section, and the transition where they meet are called shoulders. I also tend to leave the shoulder are a bit thicker than the tang and blade portion (or at the very least as thick as the blade) in order to give myself some room for corrections when the taper of the tang is cleaned up on the belt sander.



As a final point that should be fairly obvious: the spine and the edge should be more or less parallel. They don’t have to be ‘straight’ in fact my preference is to always have a slight curve to the blade. But straight or curved, the spine and the edge should have the same profile. Additionally, the spine should be forged a bit thicker than what you want it to be in the end, because you will need that space to clean up the sides of the blank and to correct minor differences in thickness.

[Gipson]

It will be something to read if someone will ask questions. Very interesting and useful topic.

[Substance]

Awesome stuff Bruno,
it is always great to see other peoples takes on making a razor,
I look forward to seeing the progress of,this article

[Bruno]

Next bit is profiling it. I use a marker to draw the outline on the blank, working with the rough shape to make sure that whatever design I am making fits correctly. That means it’s not just a matter of making the outline, but the location of the shoulders has to match the shoulders on the blank to prevent wrong tapers. I also drill the pivot hole at this stage. In case you were wondering: no special method was used for the alignment of the hole perpendicular to the blade. I work with 2 mm drills for 1/16” holes. That is tight enough to not have slop in the pivot, while allowing enough room that the alignment of the razor in the scales depends only on the taper of the tang.



With that out of the way, I flatten the sides of the spine. This is a pretty important step, because the resulting flats are used to position the hollows of the blade. It is important that those sides are as close to vertical as you can make them. The spine is curved (pretty much always is with my designs) and if the sides of the spine are not ground perfectly vertical, the top view of the spine will look wonky. It will either look bellied or anorectic, depending on which way you did it wrong.

Note that at a future point, you will change that and it will no longer be vertical but kind of slanted. But at this point, they need to be vertical. Here you also see that the tang is tapered, because the flat ends about ½” into the tang.



Now, one thing that is absolutely crucial, and which is the number one mistake of knife makers venturing into the world of straight razors. The thickness of the spine needs to be at least ¼ of the width of the blade, and at most 1/3. This means that a razor that is 1” wide, the thickness of the spine needs to be at least ¼” and preferably a little bit thicker than that still. If the spine is too thin, a 3/16” thick spine on a 1” wide razor for example, that is what we would call a razor shaped object. It may look pretty, but it will be as useful as a bullet proof vest made from paper mache.

Now comes the first grind. I use a 8” diameter wheel with a 40 grit belt to make a first hollow in the sides of the blank. I do this to verify the geometry and to help me align the edge with the spine and the tang. This, like all the rest, is done freehand and eyeballed.



You’ll notice that there are a still a couple of places that have some scale. That doesn’t matter at this point. All I care about at this stage is that there are no defects, that the edge is parallel with the spine, and that when you look straight at the edge, it will be in the middle of the blade, and if you look at the edge from the front of the razor, it runs straight through the tang. This is perfectly demonstrated in the next picture by the red line.



The alignment needs to be correct already. It doesn’t matter if it is still a bit too thick at various points. But if at this point you would see that the edge does not align with the middle of the tang, you might as well throw it away because it is never going to be a razor. It’s better to determine this as soon in the process as possible. This way, if you make a mistake, you can discover it before you’ve sunk a whole lot of time into the project.

And this is also why I don’t bother with angles and calipers or other things to perform measurements. The human eye is very good at seeing if things are aligned or not. You may not be able to measure an exact angle this way, but you will very easily be able to determine if things are in line or not by looking.

Now that I know the alignment is sound, I start tapering the tang further. With tool steel I usually make things a bit closer to the final shape because there it makes sense to optimize the amount of steel that is used (money), and the amount of time I need to remove metal from the tang (time). As I explained earlier, with this Damascus, I can only get 2 razors out of a bar anyway, and if I cut it took close I might no longer be able to make the exact thing I wanted to make. If the razor is my own design, the latter is not a big problem because I can update the design, but for a commissioned razor, that would be more problematic.

I work the sides of the tang against the flat platen of my belt grinder to clear up the forging scale until the area directly around the pivot hole is clean and then I take out my taper verification tool. In my razors, the alignment is done solely by the taper. This means that before I clean up further, I have to ensure that when the blade is put in scales, it will center in the middle.



To do this verification, I use a 1/16” screw to mount 2 rectangular bits of wood to the blade as if they were scales. The thrust washers are important for the purpose of clearing the shoulders. With the mockup scales in place, I ‘close’ the setup and verify 2 things. The first is easy. The blade has to align through the middle. If one of the scales is at a different angle, this is highly noticeable and you can correct this easily by grinding away some more material at a different angle.

The second thing you need to check is that if you look head on at this setup, the scales are symmetrical in relation to the blade. The scales have to be either vertical, or they can be angled a bit outward on the top side. Which it is, is not really important but they have to be symmetrical. One vertical and the other angled outward a bit, is asking for problems much later in the process. Like the first issue, this is fairly easily to compensate for by removing some metal.



Once the taper is aligned properly in relation to the blade, I clean up the blade further, and deepen the hollows with a smaller radius wheel. All the geometry altering work is now done. I do the final part of the hollow grinding with a 80 grit belt. The rest of the blade gets ground to 240 grit to minimize the amount of post HT sanding needed. You'll also notice that I slanted the sides of the spine inward a bit by running it lengthwise against the wheel. I do this to make sure that if the blade is honed without using tape to protect the spine, the contact line will not develop into wide honewear.

The sides of the tang are cleaned up with 240 last, after I chisel in my makers mark. When everything is polished up, I do any file work I want to do. I do that after polishing, because polishing after filing can too easily ruin the file work.
This is what I ended up with.



The thickness left at the edge is a matter of experience. You will want to keep as little as possible in place, because post HT grinding is a lot more time consuming. On the other hand: you have to leave enough that you avoid decarburization of the core steel, and you need enough thermal mass to get from the heat to the quench tank without dropping below critical temperature. The is also the risk of potato chipping the edge if the steel is too thin. For beginning razor makers, my rule of thumb is to leave 1/16 thickness, and figure out by experience just how thin you can go.

I heat treat by placing a flattened iron pipe in my fire, bringing that to orange heat, and then inserting the blade into the pipe. I wait until everything is at the right kind of orange, then I take out the blade and quench it in maize oil. When that is done, I let it air cool while I do the rest of the heat treatment. For tempering I clean up the blade with dishwasher detergent, wrap it in aluminium foil, and put it in a pre-heated oven on 200 degrees Celsius for an hour or 2.



That concludes the stage I call ‘rough grinding’.

[Bruno]

This is the state of the razor as I have it now. I'll do the finish grinding, etching and scales next week so the next installment will be here in a week or so.

[Gipson]

We are waiting for new photos look very interesting and helpful to me personally.

[Substance]

Really like the idea of using the false scales to check the alignment of the pivot early.
A Method to definitely be added to my process Thanks