Fredeen Blades

I saw your latest knife at purgatory ironworks.  That is a really nice knife.  Was that a special commission or just something you wanted to build?  

Saw the Modified Kard on IFI. Its beautiful and that comes from someone who doesn't even make blades.

Thanks guys.

This blade was just something I did. It started as an experiment in hamon. Didn't have a particular blade design in mind or anything when I started it, it just kind of happend along, let the steel become what it wanted to. Certainly wasnt going for a Kard, but once I got the blade all ground, I started looking at what to call it, and it seemed to fit closest to a Kard, save for the large and prounounced choil, so thats what I called it.

I usually dont go into making a blade with a design in mind, unless its for commission, or unless I'm really interested in a particular style at the moment. Often I'll just start forging and as the steel takes shape I start to picture what the blade will turn out to be in my mind. Kind of an interesting way of working, as you don't know what you'll get until its done.

And welcome Rob, glad to have you. If you want to know anything about blademaking, don't hesitate. I also do the occasional blacksmithing work (ornamental stuff usually, decorative hooks, steel roses, that sort of thing, plus tools, as I need them) if thats more up your alley and something you want to discuss. Let me know and I'll add another section to the forum.

That is an impressive demo with the paper cutting in mid air.   I assume that the knife is quite thin to be able to cut like that.  Did you forge it down to less than 1/8"  or leave it thicker and grind down to final size?

ernie

The blade is a bit over 1/8" thick at its thickest point, then it has some good distal taper to it. Its not horribly thin in all honesty. Thick blades can cut like this as well, its mostly a function of the edge quality and geometry, and a little bit dependend on the overall blade geometry. The cutting edge geometry determines how sharp the blade is, and the blade geometry dictates how well it will move through material. Additionally, the blade geometry (by blade geometry I mean overall dimensions, and type of grind, flat, convex, hollow, etc) will in turn somewhat restrict your edge geometry. You wont be able to put as an acute cutting ege on a thick blade with convex grind, as you would on a flat ground or hollow ground blade of the same dimensions. Heat treatment will also greatly effect the edge quality and dictate edge geometry. A good hard edge has enough structure and rigidity to support itself when its very thin, so a more acute angle can be achieved and the sharper the edge can be made. So in essence it comes down to sharpening techinque and skill, as well as the quality of your steel and heat treatment. In an effort to not make this post 10 pages long, I better stop there in terms of edge theory. I've gotten into some heated discussion about it all in the past, and have written loads and loads on the subject, and the more I get into it, the more and more I'll end up writing. I'd be happy to discuss it further if you want, but dont want to bore you to death with pages of writing if you don't want it.

As for the blade, always follow the old bladesmiths proverb "if a blade is what you wish to win, forge it thick, grind it thin." I always forge my blades over sized, not horribly oversized, but enough to give room for clean up, and adjustment. Its far too easy to ruin a blade on the grinder, so best to leave some extra for the mistake that is bound to happen (and it always seems to, don't think I've ever ground a knife that hasnt given me some sort of issue that needed correcting. I probably forged this down to 3/16" or so, maybe a hair under, then ground to final size. You need that extra just to get rid of the scale and pitting from the forging process alone, and then a hair more just in case you slip up. When first starting with blades, I always recomend people to leave their blades a good deal thicker than they want the finished blade to be (plus most havent developed the forging skill to take it really close to final shape anyway), and as you progress and get better, then you can start forging closer and closer to final shape and size.  

Don't worry about writing too much,  I am here to learn.  I have a couple of books by Jim Hrisoulas and his writing appears to agree with your analysis of blade design.  

One thing he talks about that sounds fishy is "packing the edge" .  I think the solution chemistry that is going on with heat treatment will override any attempt to mechanically modify the grain structure.

ernie

I know Jim talked about edge packing in is first (maybe second?) book, and these works were done really early on in his career, I believe he has since then recanted this theory as he now as a Phd in Metallurgy.

Your assumptions about edge packing are correct, assuming proper HT procedure is followed. If you properly normalize a blade, the retained grain size and structure of the blade from all of the forging/grinding processes will be erased, thats really the whole idea behind normalizing, to "clean up" the grain structure of the steel. Hence when you go for the hardening quench there will not be any microstructure that was directly related to physical manipulation of the grain (as well as differences in heating and cooling resulting from the forging process). Well, I suppose there could be "some" as not all grain transformation will be entirely complete, but we are talking so very very small differences in grain structure that its absolutly insiginficant, and probably near impossible to tell, even under the microscope.

However, if you did not normalize the blade after you performed the "edge packing" it is possible for some of that physical attempt to modify the grain structure to still remain in the finished steel. The effect will be very minimal, and its questionable if there is truely any noticable effect doing this. I've never came across any quantifible evidence that "edge packing" produces any worth while performance characteristics, and considering I don't know of too many bladesmiths, professionals, master smiths, and even hobbiests who believe in the theory, I don't believe that it will do much of anything, save give your hammer arm a bit of a work out. Or you risk inducing stress fractures in the edge by cold working it.

The arguement I got into with the fellow regarding edge theory was about whether the overall blade geometry played a major role in the overall sharpness that the blade could recieve. I argued that blade geometry plays a major role in the overall edge geometry and therefore sharpness. His argument was that blade geometry has nothing to do with the sharpness of the blade or edge geometry. Instead he argued that any blade could be made as sharp as the next as you grind the edge on separately after the blade is finished, and you just set the angle for the edge geometry then. Instead he said that HT played the biggest role in edge sharpness. While I certainly agree with HT playing a major role in HT, it does not ultimately dictate whether a blade will be sharp, that is dependent on the final geometry of the edge (angle and shape of the cutting edge). You could have a blade with perfect HT that will be dull as a butter knife without proper edge geometry. Instead I argue that it is ultimately edge geometry that makes a knife sharp and that proper HT is necessary to provide the structure to support a very acute, sharp edge, and that the more acute the edge angle, the sharper it will be, so long as there is enough microstructure in the edge to properly support it (in other words there is a limit that can be reached). He didn't seem to pick up on the exact point I was making with this argument and instead thought I was saying that you could grind a paper thin ege on something and expect it to be much sharper than something else (granted this would be true, save that the steel could not support it so it would colapse and fold over very quickly). 

The fellow seemed to be really focused on only secondary edge bevels (I refer to the primary bevel as the main "big" bevels on the blade geometry, a secondary edge bevel would be if you took the blade and ground an edge with a different angle at the end of the primary bevels), and only wanted to look at the edge itself and didnt seem to think the structure and blade geometry supporting the edge was of much consequence. I firstly pointed out that there were different edge types that did not include a secondary edge bevel (full flat grinds, full convex grinds, even full hollow grinds on some really really hard and sharp razors). Additionally I pointed out that there can also be differences in edge geometry itself, you can have a flat ground secondary bevel, a convex edge, even a slightly hollow edge, and that each of these would effect firstly edge durability, but additionally play a role in the sharpness, over just the angle at which it is ground. And my final arguement, which finally gets back to the main issue, is that your blade geometry will dictate the overall dimension and structure of the blade at the point where the edge begins. So given three blades, one flat ground, one hollow ground, and one convex ground, all of the same overall dimensions (blade thickness and blade width) you will not be able to put as an acute edge on the convex blade as you would on the flat ground blade, and the hollow ground blade can recieve the most acute cutting edge of the three. This is not to say you cant get each of them shaving sharp, just that the separate blade geometries will effect the maximum attainable sharpness (assuming you have the microstructure to support it). Anyway, that was the main ideas of the edge theory discussion I had with this guy, there was a lot of back and forth and repitition to try and get some points across, his arguments were not incorrect, if you only look at the cutting edge itself, but in the bigger picture there are many other factors that play a role.  

Well, you won that discussion.  All he has to do is a practical test such as cutting vegtables or rope.  A convex grind will not perform as well as a flat or hollow grind when cutting thick items.  Just look at a straight razor or a kitchen knife design, convex grinds are best used in axes.

I have done a little carving for signs and the grind on chisels makes a great deal of difference, especially on sign foam where the material does not break out easily like wood does.  You really have to push hard if the profile is too thick.

Something else that bothers me is when people say the knife edge has a micro rough edge that looks like a saw blade or serrations.  I have taken SEM photos of a polished carving knife blade and it showed no scratches or edge roughness even at 5000X.   Of course it is possible to make rough edges but that is not desired for best carving performance.

ernie

There is some validity to "micro serations" but as you mentioned, there are different ways to grind an edge, some which create, and some which remove. If you've ever used a knife with a rougher ground edge to slice through something, versus an edge which you've taken to a buffing wheel or power strope, you'll definately be able to feel the difference. The rougher ground edge will have a bit more bite into the material, and looking at it under the microscope, you would see some jagged "serations" (they aren't really serrations, as they arent very uniform, but none the less). Look at the finely ground edge that has been polished and you wont really see too much, if anything. Now all blades and all edges will have some jaggedness, and some "micro serration" even super polished edges, however the jaggedness is so fine and small you'd definately need to look closer than 5000X to see it. Either way, the concept does exist and is a legitimate theory. I don't really like the name, as the blade is not serrated, but thats what it is known as, to me it just a part of the edge geometry and edge makup, not some special property you instill within the blade. Its easy to control the "micro serrations" just by what grit you grind the edge to, and how much stropping it recieves.

Of course, as you mentioned, different edge roughnesses (I think thats a more fitting term) are desired for different cutting tasks. You don't want a super rough edge if you are trying to make a straight razor, and likewise, you dont want a super fine polished edge on a knife that you are going to be putting through some serous abuse. It all boils down to the same ideas regarding proper blade design, design a knife for the tasks and uses it is intended to do, likewise, sharpen the knife to match those inteded uses as well.