Introduction: Handmade Wood Gouge From an Old Coil Spring
Recently, I have had an increased interest in woodworking. I still prefer steel to wood, but I want to increase my skills and knowledge of woodworking, which will help in knife and tool making, and is just a generally good skill to have. My inspiration is from these great tools available from Ashley Iles. These are great handmade tools, made in the UK. I am a blacksmith, so I can make my own similar (but not comparable) tools for a smaller price than the average £20-£30 that their tools are. £20 is not a bad price for a handmade tool that will last a lifetime, but I wanted to show how you can make your own similar tool, which will cost you almost nothing.
Hopefully, you will be able to follow my instructions and make your own wood gouge if you so choose. Even if you don't, I will teach you a little about blacksmithing, metallurgy, and edge sharpening, so you can take the foundations of these skills and apply them in your own ways. I hope you enjoy.
Step 1: Tools and Materials
To make the gouge in its simplest form, the bare essentials you will need are:
-A good heat source
-An anvil-like surface
-Some type of good hammer (a claw hammer is not preferred, but would work in a pinch)
-Obviously, a coil spring or other similar piece of tool steel.
-Hacksaw or angle grinder
-Some kind of vise
To build mine I used:
-Hardened steel anvil
-1.5-lb rounding hammer and a 3-lb blacksmith's mini-sledge.
-1"x32" Delta belt grinder with 80 and 120-grit Norton belts.
-Bench grinder with wire wheel
-Heavy mounted vise
-Coil spring (obviously)
These are the main tools used. I will cover sharpening supplies later on. Before we get started, let me explain some of the tools a little bit.
This is the most difficult part to get right in the whole project. I used the Oxy-Acetylene torch because it is easy and quick to set up and use, and it provides good targeted heating. Any Oxy-Fuel setup would work, really. You could pretty easily do this on a coal or gas forge, or even charcoal. The fire has to be hot enough and concentrated enough to heat up the metal to forging temperature quickly, or else the project would take literally forever. A propane torch might work, but it would take a while. If you only have a propane torch as a heat source, I can give a few tips.
You should use the blue propane tanks, instead of the little camping ones. The camping ones do not hold very much fuel and have pretty crappy performance on high-output torches. You should also use multiple torches, or have a insulating layer behind the metal, such as an alumina firebrick or a ceramic shield. You want to catch as much heat as possible, because you don't have very many BTUs to waste.
As for me, I just set up my Oxy-Acetylene torch to a neutral flame like I would if I were welding with it. It is important not to burn the steel. More on that later.
This is another important tool that you can't really live without. Luckily, useable surfaces are too difficult to find if you look around.
If you don't have a real anvil, you have a few options. First, you could buy an inexpensive one. This is pretty easy to do. For over two years I used a 55-lb cast iron anvil from Harbor Freight. I paid less than $60 for the anvil. It is not a perfect anvil, and I have multiple complaints about it, but it works really well for being $60, as opposed to the $325 I spent for a 65-lb antique anvil. You don't really need to buy an anvil, though, if you don't want to. You can use a section of railroad track, a solid chunk of plain low-carbon steel, or even use one of the vises that have little anvil faces. You have a few good options to choose from. The biggest thing is that it can't be brittle, like a cinder block, (I've tried before, it does not work) and is preferably metallic and rigid.
Step 2: Remove Your Piece of Spring
For this project, the metal we will be using is an automotive coil spring. I got mine from an "iron in the hat" raffle at a local IBA chapter meet. You can probably buy these at local auto shops, scrapyards or online for cheap if they are not attached to a vehicle...
Coil springs are made of generally very good steel, primarily spring steels. Spring steels are made to be flexible, and are made to carry sustained loads and bend without deformation or breaking. They are usually AISISAE standard steels 1060, 1070, or 5160. The 10xx steels are low alloy steels, and the last two numbers are "points" of carbon. For example, the "70" in "1070" means that the steel is roughly .70% carbon, which means that roughly 99.3% of the steel is other things, mainly iron. Low alloy steels, also called plain carbon steels, are popular with edged tool and knife makers because of their low cost, good edge retention and easy working. 1080 and 1095 are the most popular low-alloy steels, but they are actually not spring steels, because they have too much carbon for regular use as a spring. 5160 is probably the most popular spring steel, being known as an alloy steel because of the added chromium and silicon, which improve its rust resistance and strength. That is all I will speak of metallurgy for now, until we heat treat the tool later on.
Before beginning work, put on your PPE. it's your own life, so you can chose what to wear. I always wear at least safety glasses, and always wear shade 6 goggles for my torch. I also recommend wearing a leather apron, but it's up to you.
The first thing we need to do is remove the flat part of the spring. At both ends of the spring, there is a section that is flat to make the spring sit upright. That material is not useable for this project, as it will be too thin. Take your angle grinder or hacksaw and take it off. You may keep it if you want, but I will not use it in this project.
After the flat portion has been removed, start your forge, pull out your torch, or prepare whatever heat source you choose to use. You need to apply heat starting at the end and gradually move inwards as you straighten the steel. My piece was about 9 or 10 inches. Get it as straight as you need to, then wait for it to air cool and cut it off. DO NOT QUENCH IN WATER!!! The steel could over-harden and crack if you put it in water while it is too hot. Be careful.
You can heat the bar and straighten it on the anvil or in the vise if you need to.
Step 3: Flatten Bar
Now we can begin to work the steel. If you are using an Oxy-Acetylene torch, I recommend chucking it in the vise firmly, but not too tight, to hold it in place. If you are not experienced with working hot metal, I recommend wearing gloves and holding the steel with tongs. I don't wear gloves at first, but as heat travels down the bar, I will.
Hold the bar in front of the torch, with the little inner cone touching the metal, but don't let it burn or melt a hole in the steel. Keep moving the steel. The initial heat will take a little bit, but reheats will be faster.
When the steel is yellow-orange, it is at the right forging temperature, which is about 1800-2000 degrees Fahrenheit. Start from the tip and travel back with the heat. Don't try to work more than 2 inches per heat.
Place the steel on the anvil. You want about half of the steel on and half off the anvil, to avoid dents, but still giving you a good grip on the piece. You should try to widen the steel more than lengthen it. It will lengthen, however. You want to try to get it as even as possible. Work by heats; hammer one side on one heat, and the other on the next. You want about 3-5 inches flattened.
Flatten the steel thin, about 1/10 of an inch thick if you can. You want to stretch the material as much as you can.
Once the steel is as flattened as you like, you can be done. Alternatively, if you want to, you can refine the shape a little. I hammered the sides a little, and fixed the intersection between the blade and handle. I also attacked mine with the wire wheel just to pretty it up a little.
Step 4: Square Up Blade (Optional)
If you want to, you can file or grind the front edge flat or round. It won't be perfectly shaped after forging, so this step is recommended. It's pretty simple, though. Just a tip for the belt sander: when squaring the front of the tip, hold it slightly diagonally to prevent damage to the abrasive belt. You can also flatten the blade in the vise if you want to make it really nice. Remove the torch if it's in the vise. I stuck mine in the hardy (tool) hole of my cast iron anvil. Heat up the gouge and crush it in the jaws of the vise. Pretty simple.
Step 5: Bevel Blade
This part is pretty simple and pretty hard at the same time. If you don't understand sharpening theory, don't worry. I'll explain how it works later. But for now, understand that this step is required, and any corners you cut on this step will come to haunt you later.
To bevel the blade on a belt grinder, hod it as vertically as possible. It is preferred to hold the blade edge up, as in picture #1. However, my belt grinder prevents me from holding it vertically enough. So holding the blade the other way may be necessary. You want about a 6-11 degree bevel. Using an 80 grit belt is recommended. Bevel both side equally.
I beveled my blade partially with a file. To do this, chuck it in a vise, or clamp it to a table, as seen in picture #2. Use the file to cut a very horizontal cut, about 6-11 degrees. This will take a long time to get done, but it is easier, less likely to mess up, and gives better results when done right. Bevel both sides evenly.
If you spend a long time on the belt grinder, especially if you move up to 120 grit belts, you may get fuzzy little 'feathers' on the edge. This is called a burr, and is not really a bad thing. You need to do that to get a good edge when it's hardened. They will be lost when we heat treat the blade, but it might save you a little work if you get tehm, as it will mean your blade is ready to be sharpened.
Step 6: Bend Blade Radius
This is one of the personal parts. You can really choose the radius for yourself, depending on what you want the tool to be for. You may decide to not bend it at all. It's up to you. If you do want to bend it, I can show you how. I did not get great pictures of this step, but they will do.
Heat up the blade as always. You never work the metal cold. Now, if you have a real anvil, set the blade in between the table and shelf, and forge it round. Hit it in the centre, then rotate the piece around while hammering to get it even. If you are having a difficult time hammering it, you can take a chisel or round punch and hold it in your hand, using the end of the punch as a hammer. However, many of you will not have an anvil. If you don't have an anvil with a good enough shelf, you can bend it on a piece of angle iron, or any metal 90 degree bend, following the same procedure.
My bend was not perfect the first time hammering, so I heated it back up and used a punch as a hammer to finish it. It turned out pretty good.
Step 7: Heat Treating
This is the part that turns the steel from a thing to a tool. There is a risk of the oil flaring up or splashing and burning you, so I recommend that wear gloves and the rest of your protective gear if you are not already. Also, the oil I used makes a lot of nasty smoke, so do this outside.
the first step before you do anything is to heat as much of the tool up as you can to a bright red/orange, and let it air cool until you can hold it with bare hands. This process is called normalization, and will reduce some of the stresses and refine the grain structure of the steel. If you so choose, you can heat it up to bright red/orange and then put it in an insulating substance, such as hardwood ashes, perlite (expanded obsidian), or sand to cool very slowly. This process is called annealing, and works to fully soften the steel and is very beneficial if you have worked it cold too much. To cool in air should take less than 30 minutes if the piece is small enough. Annealing, however, can take hours to cool fully.
After everything is done cooling, take your heat source outside if possible. I wheeled my Oxy-Acetylene torch outside the shed to avoid any tripping or spill hazards. I chucked my torch in a little vise that's not bolted down so I could film. (If you are using a torch like me, you can just hold it in your hand and the gouge in the other if you don't have a vise.)
I only heated up about an inch of the tip, because that's all that would fit into my little quench bowl. I propped up the bowl to get the deepest possible pool of oil. I am using regular motor oil, but vegetable or mineral oil will work quite well also. Use what you have and what you feel comfortable with. Vegetable oil and mineral oil have their own quirks. They are both more "earth-friendly" than motor oil, but they can be more dangerous to humans, as they boil and combust more violently and easily. Theses two oils are very popular for spring steels.
The picture does not quite capture the true color of the steel. It looks red, but it was really orange when I quenched. That is the right temperature for a coil spring. I recommend doing this in a shadowed area to get an accurate color identification.
Take care not to ram the front of the tool into the bottom of your oil tub. Most likely, the quench will go fine, with no bends or cracks. If a minor bend shows up, you can fix it while it's hot. If it is large, you will need to reheat it and fix it, and go through the whole thermal cycle again. If a minor crack appears, it may be fine. It there is major cracking, there is probably no hope.
Let's condense this for you: Heat to orange, quench in oil carefully. You have 2 temper options: you can quench temper it, or oven temper it. To quench temper, while you are quenching, watch the color of the blade. As soon as there is no visible red, pull the blade out of the oil, count to 3, and re-quench in the oil to finish.
The other way to temper is this: Quench the blade and do not remove it from the oil for about 15 seconds after the red is gone. After 15 seconds, remove it from the oil, let it air cool, and wipe off as much oil as possible. Then, put it in a toaster oven or kitchen oven. Start the oven for about 400-450 degrees fahrenheit. Cook the knife for more than 4 hours, and then take the knife out and quench in oil. The knife will smoke if there is oil on it when you put it in the oven, so maybe consider quenching in vegetable oil.
Step 8: Inspect and Clean the Blade
If your quench went right, there should be a distinct whitish area in the part of your tool that you heat treated. It will possibly have scaly black/gray stuff on it as well. That is the first indicator that your blade is good. Next, take a nice, sharp file and try to file the blade with it. The file should slide off of the hard part. If it is not obvious, try to file some of your coil spring, if you have any. The difference should be obvious.
If there is any stubborn oil residue, clean the tool with windex, and use a wire brush or wheel to clean off the scale.
Step 9: Sharpen the Blade
This is the part that will turn your tool from a paperweight into a useable gouge. For more information on basic sharpening, see this good article.
To begin, if you are using a belt grinder, put a 120-grit belt on. If you don't have a belt grinder, skip to the next part. When using the grinder, try to match your original angle. This is the part that you should have been preparing for. If you put enough work in while beveling, you should have an easy time here. Grind the outside first on the 120 grit belt. Next, grind inside as good as you can. Hopefully, you don't need to do too much work inside, but if you do, have patience. Use the edge of the slack belt the get the inside. You need to do this until you get the burrs on one side, then knock them down on the other side. Once you have the burr going, skip the next part and go to the stones.
If you don't have a belt grinder, find your best files. You need a smooth or second cut half-round or round file. Chuck your gouge in the vise being careful not to damage the edge, and get to work. You need to file until you get the burrs on one side, then knock them down on the other side. Do this a few times on your second finest file, and then on your finest files.
Here is where is gets a little more difficult, and you need to evaluate your tools. Ideally, you would use slip stones, but I don't have any. I have a triple-bar sharpener that matches my gouge's radius quite well. But any other gouges I make won't fit it well. If you don't have slipstones, a bar sharpener, or the radius does not fit your bar sharpener, you need to be creative. I will show you how to make your own kind of slipstone from a soft Arkansas stone.
I purchased a small little Arkansas stone from a survival supply store for around $5. It has nice little square edges that do not do anything particularly useful. So, I decided to round one of them off to make a slip stone. All I did was fire up my belt grinder with an 80 grit belt, and went to work. I rounded the edge on the slack belt. I most certainly advise using a respirator or dust mask, as breathing mildly abrasive stone powder is not particularly good for you. You could use a file for this if you needed to. Use what you can. Sorry my photos are bad, but I was one-handing it, and did not even look at the pictures until I was done. Also, none of the pictures showed me sharpening the outside edge, because that is the easy part and I forgot to take pictures. That step is important, though.
The stones I used:
-$3 Harbor Freight coarse/medium sharpening stone
-$5 Soft Arkansas stone
-Antique Dexter/Russell 3-Way
If you don't know how to sharpen with stones, it's pretty simple. You match the original angle that you ground with the files or belt grinder, and then you run the blade lightly across the stones, alternating sides, going from coarse to fine. If you apply too much pressure, the edge will never be sharp.
Once you think the edge is sharp, go test it out. If it's not good enough, have patience and go sharpen it again!
I did do any stropping or rouge sharpening, as the edge was not fine enough for that.
Step 10: Enjoy!
I hope that I was able to teach you a little bit about metalworking, and I hope that you can take what I've taught you and use it for yourself! Thanks for reading! Please consider voting for me in the Build a Tool 2017 contest if you so choose! I would love to hear your opinions and feedback, and I am looking forward to seeing what you make!