Make Your Own Bush Knife (Part 2)
We got our home forge set up in part 1 of this article. In this second and final part, we offer a quick review of the steps necessary to flatten and draw out raw steel into a workpiece and how to forge the blade, point and handle. We also review the necessary thermal treatments and finishing operations to the final product.
In part 1 of this article, we discussed how to get started forging your own knife. We considered the tools that you would need, the selection of a knife design, the selection of the right steel and making a simple forge for use at home.
Now that we’ve gotten this far, it’s time to get to work.
Hammers, Tongs and Anvils
There are many types of hammers and other tools used in decorative forging. Choosing the right ones comes down to personal preference. If I had to choose just one hammer, it would be a cross-peen hammer, which is used to draw out thicker metal pieces. Other hammer types include ball-peen, planishing, sledge and dog-face – each has its own specific characteristics and uses. Similarly, there are many varieties of tongs, which are essential to forging a blade or anything else. If you could only have one pair of tongs, choose the wolf-jaw design because they can hold just about anything.
A 100-pound anvil is almost never less than $400, and new anvils cost even more. When seeking an anvil, avoid cast iron, which will dent and chip away over time. In a pinch, visit a scrapyard and find a piece of railroad track at least 50 pounds or more in weight. Attach it to a solid base like a large tree stump, which I prefer because its grain helps absorb hammer blows.
Working Hot Steel
When working steel, let the fire do most of the work. Yellow-hot steel moves better and easier than red-hot steel. A rule of thumb is to stop hammering the workpiece before it loses its color or you run the risk of cracking or fracturing it.
When forging steel, you will encounter scale, the oxidation that forms on the hot workpiece. It is better to remove scale with a wire brush as you go along rather than hammering it into the workpiece, which causes issues down the road. When Damascus steel is being forged, a fluxing agent is used to prevent scale from building up when the layered billet is initially forge-welded.
Forging the Blade
The goal of forging is to finish at least 90% of your profiling with a hammer and to clean up the last 10% with a grinder.
Whatever shape of steel you start with, the first task is to create a flat surface and achieve the desired width. Once at the proper width, you can draw out the steel in length until you reach the proper thickness. Using a cross-peen hammer, strike the steel perpendicularly down the length of the workpiece, elongating and thinning it as you go. Next, flatten out both sides of the workpiece with a flat hammer on the opposite side of your cross-peen until you have removed the perpendicular strike marks.
If you want to thicken portions of the drawn-out steel, hammer on the sides (edges) of the workpiece. This is often referred to as “upsetting” the steel. Be sure to re-flatten the steel every time you do this, or you may roll an edge or corner over itself and bury small pockets (called cold shuts) into the steel.
Forging Point, Pounding Bevels, Profiling Handle
Draw out the steel until you are close to the desired thickness and width. Then you can start working on the point of the blade. To do this, focus the heat toward the end (tip) of the workpiece. Begin shaping the material by hammering in the corner. When you notice the side of the steel fattening, lay it flat and spread out the thickness to keep it from mushrooming.
Beveling the edge can be done with a file or grinder, but I prefer to hammer in the bevels. When hammering down the entire length of the blade’s edge, use your hammer at an angle rather than striking straight down. Do this on both sides of the edge. This isn’t the sharp final edge, just the beginnings of it.
Once you have your point in place, you’ll need to profile the handle to fit a human hand. I form the handle profile by making a light strike onto the spine of the blade over the anvil’s edge to form a slight dent. I use that dent as a reference point and upset all the steel on the handle side of the dent. The horn of your anvil can be used to create an ergonomic design.
Be vigilant about flattening your workpiece and straightening the spine of the blade during these operations.
With your workpiece roughly shaped, it is time to anneal it. This involves heating the steel and allowing it to cool very slowly, making the steel softer and more workable for subsequent operations.
Many smiths will heat their blade and leave it to cool in the forge, but I prefer to cool it in a dry medium such as a bucket of powdered charcoal or sand. Slowly plunging a heated blade into it will force it to cool very slowly.
The Next Steps
At this point, you are essentially finished with the metal deformation aspects of bladesmithing. Though beyond the scope of this article, my book describes the steps and tools necessary to complete your knife. These include:
- Locating and cutting the plunge line
- Grinding the bevel of your blade and forming a preliminary edge
- Preparing the tang, or portion of the workpiece that extends into, and is held by, the handle
Normalizing, Hardening and Tempering the Blade
Your blade is now ready to be hardened. Before that, however, it must be normalized. Normalizing resets and redistributes the steel ingredients and relieves the stresses inside the steel caused by hammering during forging. To normalize the workpiece, heat it to 1500-1600ºF and let it cool in still air until all the color has left the blade.
Quenching is the process of heating the edge of the blade and dunking it into a quenchant such as oil, water, polymer solution or brine. Quenching causes the formation of martensite, which is the hardest of steel’s phases. However, this level of hardness is too extreme for a usable blade, which might otherwise shatter in service. Therefore, we must temper the blade after quenching. When properly performed, tempering will balance the hardness and the toughness of your blade.
Having made it this far, you are now ready for the final steps, which are also beyond the scope of this article. These include:
- Cleaning the workpiece
- Creating the cutting edge and honing the blade
- Choosing and sourcing the right handle material
- Handle assembly and attachment
- Shaping the handle
- Finishing the knife
- Care and maintenance
What we have covered here is but a simple summary of how to finish your bush knife, with an emphasis on the metalworking aspects. There are many additional illustrations, details and tips on how to succeed in my book. If you take your time and practice each step as needed, you will end up with more that just a beautiful, usable knife – you will have a family heirloom.
This article has been excerpted by permission from Making Your Own Bush Knife: A Beginner’s Guide for the Backyard Knifemaker, by Bradley Richardson. The 184-page book from Fox Chapel Publishing (Lancaster, Pa.) is full of additional helpful tips and illustrations to help guide you through the knifemaking process. Author Bradley Richardson is an outdoorsman and master knifemaker who founded Timberlee Tool & Trade, Traverse City, Mich. Questions should be addressed to https://timberlee.com. For additional information about the book, please visit https://www.foxchapelpublishing.com/making-your-own-bush-knife.html.