Bush craft knives are great, and a perfectly fine product of knife making. However, there is nothing quite like the elegance, and the ubiquity of utility of a kitchen knife. Every one needs one, they each have serve a specific purpose, and can cost a considerable amount.
All that together means I have to try it.
The first knife every one needs is a proper chef's knife. It can handle any task in the kitchen, and in fact is used to handle most kitchen tasks. For this knife I used 1095 steel for it's decent cutting ability and ease of sharpening. Another motivation to choose this steel is for it's ability to show hamon lines.
A hamon is the result of a differentialy hardened blade that has been acid etched. The varying hardness in the steel causes the acid to etch differently, creating a hamon. This technique is primarily used in Japanese sword making. For kitchen knives, it's merely cosmetic. But it's dang cool.
The basic process is simple, cover the spine of the blade in a layer of insulating clay (I used satanite). Allow it to dry, and then proceed with the heat treating as per normal.
Diferentially hardening causes some rather undue stress on the blade. So it's important that you take as many precautions as possible. My first attempt warped beyond repair, and I had to call the whole thing a loss. First of all, it's important that the bevel is not ground all the way. I'm using 1/16" stock, which I've decided is too thin to actually do any beveling prior to heat treat. If you do bevel before the heat treat, be sure you do the best you can to make them even. Variation in the grind will cause uneven forces to happen during the quench.
Secondly, I did not do this for either blade. But a very common and supposedly effective method for differentially hardening is to cover the entire blade in clay, with a thicker application on the spine. This reduces the gradient of forces being applied and increases your chances for success.
Once you've successfully quenched a blade,you can move onto the fun part - The Etch.
I used ferric chloride acid to get this hamon. At first I tried using it full strength in a plastic tub that was too small. This caused some unfortunate discoloration where the blade was not fully submerged, and the level of concentration etched the blade too quickly for a decent looking hamon. I had to polish it out a number of times before I learned you're supposed to dilute the acid before you use it. That also gave me enough solution to fill a container that could actually hold the entire knife blade. I left it to etch for 5 - 10 minutes. But it's perfectly fine to pull the knife out of the solution, clean it off, check the amount of etching, and re-submerge it in the solution if it's not ready yet.
Acid etching steel causes a lot of oxides to build up. These are pretty easily removed with steel wool and dish soap. And the final little bits were vigorously rubbed out using flitz polish. I can't say if the polish was actually worth the effort. But it did clean up some of the final subtle darkening caused by the oxides.
I've been able to get away with simple tools for grinding my knives. But it's never been quite right. Angle grinders are inaccurate, small belt grinders are underpowerd, and over heat quickly. For a long time I've known that I need a proper belt grinder. But I've never quite had the tools to do it.
Until now! I bought a Forney mig/stick/tig welder, and decided to tackle this project.
I'll be honest here. My welds are terrible. I should have practiced before welding the real thing, but I was excited, and just went for it. They do hold! You'll notice in this first picture the two square tubes don't quite line up. This has caused the wheels to not be square with each other. I haven't been able to test this yet with a real belt, so I can't say for sure this will be a serious issue. But I should have paid better attention to this :(
I drilled and tapped two holes for set screws. One will set the tensioner, and the other will set the tool arm. Fun fact, this was the first time I've ever tapped a hole!
Belt tracking is likely the most complicated part of the belt grinder. The pictures will do a better job at explaining the set up. But I'm using a bolt to adjust the angle of a hinged piece of steel.
The whole tracking set up is also the tensioner. The tensioner tube is inserted into the larger diameter tube with a spring in the bottom of it.
Here it is all screwed together!
So here is something I learned about the wheels and the bolts being used for their axles. The bolt should not tighten around the wheel! Untill I thought about it last night, I thought the bolt was supposed to death grip the wheel so it isn't loose, and holds the wheel in place while the bearing does the spinning. But in fact, you should use a second nut to secure the axle in place, and put no pressure on the wheels themselves. That way the axle is tight, and the wheel is allowed to spin freely. Plus, the wheel is plastic, and overtightening may damage them.
My setup is rather ghetto. I'm using a bench grinder as the motor. And I have it, along with the belt grinder clamped to a bench. I finally got it to track properly, but the belt is obviously running uneven, probably due to the misaligned weld (or the misaligned bench grinder clamped to the bench.) My next step is to built a platen, and tool rest. Then fix the misalignment weld, and hopefully find a way to align the motor with the grinder better.
So I've been thinking about getting into blacksmithing. My ultimate goal is to forge a damascus steel knife, but one step at a time.
A coal forge is the traditional blacksmiths fire. I figured I'd start there, and a bought 50 pounds of coal before I even had the forge. Probably not the best idea, but I hate it when I finish building something, and then have to wait for more materials before I can actually use it.
Word of Warning, this is a chronicle of failure. This whole idea was a complete flop, but I learned some things. At the end of this I'll talk about what I'm going to do better.
While perusing the store looking for a fire pot, I saw this metal pail. It was the best I could find, so I bought it. A better firepot would be welded out of thicker steel, or made from a brake drum. But Neither of those are options yet. But someday soon!
I made the tuyere from some pipe fittings, and capped the bottom so the ashes could be cleared.
I filled the inside of the pail with kaowool and covered it in satanite. Leaving the center cleared for the airway.
Most coal forges that I've seen have some sort of diffuser for the air. I drilled some holes in a sheet of steel that I'll place on top of the forge. This should hold the coal and provide some scattering of the air.
Now here's the part where I talk about the total failure this project was. Not every project is going to be a success, but you hope that you learn something from the experience. Which I did :)
First of all, the coal was a lot more difficult to ignite than I thought it would be. Turns out, that it's harder to light then charcoal. You've gotta pile the charcoal around a fire with enough substance to turn the charcoal into coke. And then ignite the coke. This requires a firepot that allows you to create a chimney, which mine did not. It wasn't deep enough, and because it was so small, there wasn't enough room to pile coal all around.
You also want the existing fire to convert the surrounding coal into coke. And for that you've gotta have the "hearth". That's the flat table top surrounding the fire pot where you store extra coal, and push it closer to the fire to began its transformation into coke.
Basically, the traditional format for a coal forge is just about perfect.
Last year when I was first getting into knives, I needed to build a forge to heat treat knives. Propane was my first choice, and I decided to tackle that.
Because blowers are expensive, I opted to go with a Venturi style burner. These tend to be a little more fickle, and a little more complicated to get right, but when you do they work great. Ron Reil is where every one gets their first inspiration for building one of these. I would suggest you look through his web page, because he's done it all.
Venturi burners work on the Bernoulli's principal, where a high velocity stream of gas creates a low pressure in the burner tube. This low pressure will draw in air that mixes with the propane and ignites in the forge chamber. The stream of gas/air mixture is moving faster than the propane is igniting. Until it reaches the chamber where it slows down enough. Since we're relying on a physical phenomena to pull air into the system, it can be temperamental, and sensitive to certain details.
The diameter of the nozzle, and the gas pressure will have an effect on the velocity of the gas, which in turn will dictate the air/fuel mixture. The geometry of the bell, and any irregularities in side of it or the nozzle can cause turbulence, or reduce the negative pressure. All of this can cause drastically different results in the performance of your forge.
Another property of significant importance is the amount of back pressure caused by the forge itself. Ideally you'll have zero back pressure, resulting in free flowing mixture of air and propane. Unfortunately this is never the case. Too much backpressure can cause a number of issues, one in particular is back burning. My paint can forge has suffered from "back burning" since day one. I've never understood what the issue is until recently.
Here is my theory: The forge chamber has a diameter of 2", and a burner tube diameter of 3/4". The rule of thumb for chamber diameters is eight times the burner tube diameter. My 2" is way too small. The forge behaves normally for 15 minutes, until it reaches a certain temperature where the back pressure becomes too great, the gas velocity slows down to a point were the flame burns back up into the bell. I'm going to upgrade to a larger forge and see if that solves the problem.
Many designs include a flare at the flame end of the burner tube. I can't say that I completely understand what advantage is provides, but I have a few ideas. In order for the flame to stay lit, the gas velocity has to be slow enough to continue the burn, but not slow in the burner tube (otherwise it would cause back burning). Without a flare, the gas would continue out the burner at full speed faster than the flame can keep up, and the gas concentration decreases below the propane flammability limit. A flare gradually increases the pressure and slows the velocity to a point where the flame stays lit at the flare. But here's the thing, the forge chamber can act as the flare. It won't be the "perfect" shape to match the gas expansion, but it will be close enough for a functioning forge. It's possible having the perfect flare improves the efficiency of the forge, but I can't say for sure.
A forced air forge doesn't have many of these issues. The air/fuel mixture depends directly on the speed of the blower and the pressure of the gas. And the burner will perform as well as the blower is able to supply enough air.
Now that we've got some of my musings out of the way, let's get to building. Naturally the best way to start is to draw it out.
For the body of the forge, I used a 1 gallon paint can. 2 inches of Kaowool and satanite to seal the fibers. It's important to seal the fibers, because you don't want little pieces of ceramic being blown out of your forge where you can breath them in. Kaowool is also not very strong, and will deteriorate rapidly if it's left exposed to the open flame, hot steel, etc. Satanite gives the inside of the forge a nice rigidity, and helps keep the forge at a stable temperature.
Here is a video of it running.
At the end of the project, I was able successfully heat treat some knives. Despite the back burning problem.
The forge is now used as a proof of concept for some blacksmithing. But the back burning is too much of a problem for this to be viable at all. Guess that means I get to rebuilt it :D I'll write up a whole post about that. But for now, here is my testing setup, complete with the original forge, and my anvil.
I'm sure at some point you've heard about various people, in an act of showmanship opening a bottle of champagne with a sword. Called "Sabrage" They rapidly slide the sword along the bottle, towards the cork, where it contacts with the glass lip. Since the contents are under pressure, the entire top of the bottle pops off, and champagne spills everywhere. Here is a video:
After a trip to Napa Valley with my wife and her parents, my father-in-law expressed some interest in trying this out. So I got in my head to try and make a saber meant for sabrage.
The first design decision I had to make was to the length of the saber. Typical sabers can be over 3 feet in length. But longer swords pose many more challenges that shorter ones. Since the sword is merely for opening bottles, I decided to keep it on the short side. Its over all length is 20".
A typical saber has a curve that extends across the whole length of the blade. Since I'm not forging this blade, and instead I'm using stock removal, getting that strong curve is difficult. You have to start with stock that is wide enough to fit the entire curved blade. The steel I had access to was only 2" wide. I tried to add a curve, but you'll notice in later pictures that it only really curved towards the tip of the blade. I accidentally cut too much off the back of the blade when I was shaping the profile. Here is an original sketch for the blades profile. I'm a firm believer in the idea that "If you can't draw it, you can't make it". So I sketch out nearly every thing until the shape looks like how I want the final product to be.
If I were a real knife making shop, I would buy (Or make) myself a proper 2" x 72" belt grinder. With a sufficiently powerful motor that can have its speed adjusted, there is nothing better. Some day I'll get around to that, but in the mean time I bought a cheap Wen 1 " x 30" belt grinder that seemed to do just fine. It was able to grind the bevels flat and evenly, and it shaped the profile well enough. It is slow, but you still get decent results.
One important downside, since it doesn't have an adjustable speed, it is way too fast for me to trust it to do any post heat treating work. I would worry that it would ruin the temper with all the heat from the friction. If I really needed to I could keep a bucket of water to cool it down between strokes. But that would probably be more work than it saves using the powered grinder.
Something I Learned: When grinding the bevels on the blade, I used a pretty coarse belt. This quickly removed material. However, it left some pretty severe gashes in the steel. Gashes that proved to be very difficult to remove by hand. Since I ground the bevels all the way to their final shape, removing the gashes meant I would have to grind past the final shape that I intended. Next time, I'm going to use the coarse belt for the coarse shaping, then switch to a finer belt to finish the shape. This should easily remove the gashes, and leave smaller scratches that can be removed later. If I had an adjustable speed belt grinder, I could wait till after the heat treating to finish grinding the bevels down to a sharp edge, which should accomplish the same thing but with fewer steps.
After the profile of the blade has been completely shaped, and the bevels ground down (Leaving about 1/16" on the edge) the blade is ready to heat treat. It's important to leave a little thickness on the blade edge before heat treating. There is always a chance that the blade will snap when quenched, but leaving a little extra material helps mitigate that risk.
The in-laws gave us one of their old kilns to do some glass working. But it's the perfect thing for heat treating blades.
The quench tank was a little more complicated than I thought it would be. Many people all over suggest using old cut open fire extinguishers, or welding a cap onto one end of a large diameter pipe. None of these suggestions were very accessible to me. I just wanted something simple and easy. So my wife and I went to Walmart, and we found the perfect thing.
A wide and shallow galvanized steel bucket meant for holding ice with bottles/cans to serve during parties. It holds 3 gallons of oil, and it is long enough to quench the whole blade. It's perfect.
Something I learned: I tried to think of all the ways to use as little oil as possible. Small thin quench tanks, etc. But It's important to have enough oil to absorb all the heat, otherwise you'll end up with a poor quench, and it won't reach full hardness. I read somewhere that the rule of thumb is 1 gallon of oil to 1 lb of steel.
I used 1084 steel for my blade. So heat treating was as simple as getting it up past non magnetic to 1500 then dunking it right into the oil. Here it is post quench. I tempered it to 500 degrees. My hypothesis is that a softer temper will be less likely to crush the glass at the contact point, which means less crushed glass flying every where.
One distinctive feature of a saber is the hand guard. It's typically made of brass, and rather ornate. Often it's a "basket" guard, where it partially wraps around the users hand. I really liked this look, and I happened to have a sheet of brass in my shop that was largely unused.
After many attempts at drawing the hand guard out, I finally came to a design I liked. It's remarkably simpler than what I started drawing, but I think it turned out nice.
To transfer the pattern to the brass, I cut it out of paper to scale, and traced it with a carbide scribe. Remember, it's important to secure the pattern to the material as best you can. Since it's paper, it slides around and you'll get a really bad transfer, like I did. :( It may have been better for me to use graphite paper and then scribed along the lines.
I had to buy a larger fret saw to cut this pattern out. I normally use a jewelers saw, which works fine for most things. But the depth of cut that I had to make made it impossible to do with a small saw.
I didn't get many pictures of the whole build, but here it is gluing the hand guard on.
Closer shot of the hand guard. Polishing it proved to be difficult, so instead I used steel wool to give it a brushed look.
One thing to note about this hand guard, it's a really poor design if you're going for durability. It's secured to the sword with epoxy at 3 different points. The epoxy should hold well enough, but it's pretty likely that it will fail under some amount of stress. Normal saber hand guards actually attach to the sword by molding around the grip. Which provides a much more secure hand guard.
After the final glue up was done, I did a quick detailing with some steel wool, and the sword is finished! Here are pictures of the sword at different angles.
Over Thanksgiving break, I got it in my mind to make knives. I thought it would be an awesome combination of metal working, and wood working. And ease me into the world of metal working. Plus, the end product would be something I could use, and give away as gifts.
When I first started researching this hobby, I wanted to use the fanciest steels, and I thought I could do the heat treating with a oxy-propane torch and a bucket of water. Oh boy, was I wrong. But I'll get to that.
Turns out, profiling the steel turned out to be fairly easy. I bought myself a Dewalt 11 amp, 4.5 inch angle grinder. And a bench grinder. With those I could draw my shape onto the steel with a sharpie, cut out a rough profile using metal cutoff disks. And then using low grit flap disks to bring the profile of the blade to exactly what I had envisioned.
The hard part, as you can imagine, was shaping the blade's bevel. I found it nearly impossible to create perfectly flat grinds. They always turned out to be slightly convex. Maybe this is something I need to over come with further practice. Or maybe I could up my file game. But I really don't like the kind of scratches files leave in the steel. They are really hard to buff out later. However I know this could be easily solved if I bought the proper tools, like a belt grinder. But until then, I will have to make do with my angle grinder and files.
These are my first knife blanks. The top is made of 1080 steel, and the bottom is O1. I have yet to actually heat treat the O1 blade, as my furnace is a little unstable. But I can heat treat 1080 with only a little trouble
This is my first fully finished knife. It's a gut hook, specifically designed for fishing. I over tempered the steel, causing it to be softer than I had hoped. However, this means the blade will be very durable for hacking through the bones of fish with nothing more than a rock as a cutting board.
I really wanted to add a kitchen knife to my repertoire. I even knew what profile. Behold my Santoku vegetable knife.
It has a single flat grind as is typical for Japanese knives. I had heard about the superior cutting performance, so I had to see for myself. Notice the ugly grooves. The goal of these grooves is to help vegetables to not stick to the blade. They didn't turn out as I had hoped, and I later saw a design that simply drilled holes. The next vegetable knife I make will have drilled holes. But I will note that I love the cutting performance of the single bevel. My diced onions have never been finer. The single right hand bevel causes the blade, when used by a right handed cutter, to cut towards the left, which counteracts the natural tendency of a double beveled blade to move towards the right hand side when cutting thin vegetables. I've also realized why most kitchen knives are made with stainless steel.
The last knife I have made as of yet I did not really design for a purpose. I just really liked the sweeping curved lines. This time I tempered it correctly.
Each and every steel knife needs to be heat treated once the profile and bevel have been ground. The idea is that the steel will become very hard, so as to hold an edge better. To do this properly, one needs a forge that can reach around 1500 degrees, and hold a specific temperature for an arbitrary amount of time. I built one, it's a venturi propane forge. But I'll leave the details for another blog post.
