All the trouble started with twig technology. As author Douglas Adams writes in Last Chance to See, "the monkeys were ambitious, and interested in all sorts of things, especially twigs, with which they found they could do all kinds of things that they couldnít do by themselves..." As the descendents of those "monkeys", tool use really sets us apart. We arenít particularly strong, but with the proper application of a twig, we created levers. We canít swim long distances, so we fixed a bunch of twigs to each other and developed boats. We donít have strong teeth or claws, so we attached sharp stones to twigs, and made spears and knives. Modern technology is amazing, but it all stems (get it?) from our love of twigs. In todayís instructable, weíre going reeeeeally retro and making our own twig technology. We'll be creating a type of stone knife called an ulu.
An ulu is a roughly axe shaped knife used mainly for processing foods and hides. Youíve probably seen flint knives before. Flint was a very popular material for prehistoric humans. When properly worked, it bears one of the sharpest possible edges. However, some cultures, such as the Inuit, did not have ready access to flint, or a similar, glassy material. Instead, these people used slate. While flint blades are made by fracturing (knapping) the stone, slate blades are made by grinding the stone, much like a steel blade.
Tools and Materials:
Safety First - Always were eye protection when working with stone, and use a respirator or other filtering mask when sanding.
Step 1: Plan Your Design
Ulus come in many shapes and sizes. This one is very compact and sturdy, but many shapes will work.
Step 2: Mark Your Slate
Use a pencil and then a nail to make an outline of the blank you want to cut.
Step 3: Cut Out Your Blank
Using the grinder or saw, carefully cut out your blade blank. Be patient. Stone is brittle, and a high-speed cutting tool could break it.
Step 4: Shape The Blank
Using a belt sander or some other form of abrasive, grind your blank into its desired shape. Again, be patient, so you donít snap your blade. You want to have a very sturdy edge, so donít make it too thin. If you are familiar with knife making, you want a convex edge. If youíre not familiar with knife making, you want to make the cross section of the blade look like a parabola, rather than a "V"
Step 5: Sharpen
Using progressively finer sandpapers, sharpen your knife. Donít forget to periodically brush or blow the dust off of the paper. Slate isnít as hard as flint, so you wonít be able to put a razor sharp edge on this knife, but it can still get sharp enough to cut vegetables, meat, and even leather. Keep in mind that this edge wonít be very durable. However, as youíll see in this step, itís very easy to resharpen..
Step 6: Wax
This step is just to make it look pretty. I used food safe countertop wax to coat my ulu. It gives the stone a nice shine, and a little protection.
Step 7: Make The Handle
While the ulu could be used without any limitation at this stage, itís a nice touch to add a handle. I chose to use a bit of elk antler, but just about any material will do. Simply use your dremel, power drill, or chisels to cut a slot large enough to hold the base of your blade.
Step 8: Attach
Iíve used hemp cord to fix my handle to my blade, so that I can separate them if the stone ever breaks. If you wanted to you could use some type of adhesive or even pine pitch or hide glue. Drill a hole through the handle, and one to match through the stone. Youíll notice my blade has 3 holes. 2 were pre-drilled because I used a slate shingle. Next, carve some grooves in your handle to hold cords in place. If you choose to use adhesive, this step is unnecessary. Finally, bind the blade to the handle using the cord.
Step 9: Complete
Congratulations, you now have your very own slate ulu! Time to bask in the glorious application of twig technology that youíve wrought with your own hands! As Iíve said before, slate knives can be used for many cutting tasks. While the edge will wear out more quickly than most knife materials, it's very easy to resharpen. Experiment with different shapes and cutting angles for different applications.