I finally decided to go ahead and build a charcoal forge to make knives out of railroad spikes, motorcycle chains, suspension springs and other junk steel. I have never done this before, but as always, I researched the subject thoroughly before diving in. My goal is to produce crude knives at first, without using any electricity. Using a grinder is thus not an option and the shape of the blade will have to be hammered as closely as possible to it’s final size. Forging a knife is one of those basic skills I think I ought to learn. Not that I expect to ever do it out of necessity. I want to experience the satisfaction of building the most basic tool with my own hands..
My first step was to find an expert on the web, and that turned out to be Tim Lively. His washtub forge seemed to fit my bill pretty well. Problem is, Home Depot didn’t have the washtub, so I settled on a large terra-cotta bowl. I hope that lining it with adobe (50/50 earthen clay and sand) like the washtub forge will prevent it from cracking.
To be able to reach forging and welding temperatures, you need to supply the burning charcoal with fresh air. I bought a bunch of pipes and fittings for that purpose:
Steel pipes assembly for forge air supply.
I used a cheap drill press from Harbor Freight to drill 1/4 inch holes in the pipe that lays at the bottom of the bowl:
Drilling 1/4” air holes in the top pipe assembly.
The assembled result looks pretty good:
Terra-cotta bowl and pipes assembly.
Using galvanized pipes isn’t the brightest idea since they release toxic gases when heated. I’ll have to work upwind to avoid poisoning myself! I suggest anyone building a forge to use something else! Forge blowers on Ebay go for about $150 to $250; more than I care to spend for an old rusted piece of cast iron. I am not sure yet what I’ll use as an air supply. Any suggestions?
Now that I have the hardware, and while the adobe dries, I need to learn how to actually forge a blade. Fortunately, Tim Lively has an excellent DVD on the subject:
Mixing the sand and clay took forever. I had to use my Khukuri to chop fist-size blocks of clay, wet them and take little flakes out until the whole thing was gone. You have to be carefull not to add too much water. I tried to obtain the consistency of peanut butter. I started packing it under the pipe. Hopefully I didn’t leave any air bubbles in the adobe. Now the mix needs to dry for a few days.. I can see little cracks already, but it’s a forge I am making, not a teapot, so it doesn’t really matter, I’ll patch them up later. I also want to raise the sides a bit so that the charcoal stays in the middle, over the air holes.
Adobe drying in the bowl, aroud the pipe with air holes.
you can buy a “log lighter bar” at most plumbing supply shops, that are made out of black steel that might work better. If you just get the galvanized pipe out of the bowl you should be OK . Iwas thinking about trying to use fire bricks and two propane pear burners.
make a box out of the bricks and have the burners come in from the side at an angle, but it would burn a lot of gas.
Thanks for the tip.. I was also thinking about using bricks, or like I saw on a web site, an old refrigirator freon tank, lined with kaowool, with a refractory plate at the bottom and a couple burners. I might “go gas” if the charcoal forge doesn’t serve it’s purpose. I saw $300 new gas forges on Ebay, that might be an option if I really turn this into a regular hobby.