So you need to start a fire and all you’ve got is some wood, some rocks, and your shoelaces.
Great, that’s all you need.
A bow drill consists of 4 components:
The Fire Board
You’ll need to gather some wood and a good sharp stone you can use as a knife, flint is ideal.
The Spindle and fireboard should both be made out of the same type of wood. You should collect the wood from a standing dead tree that has clear sun exposure, so it’s bone dry. Starting with damp materials is bullshit. Most guides recommend cedar, which has a distinct scent, so if you know what it smells like, it’s easy to identify; but most medium strength (not evergreens or hardwoods) will work just fine.
The spindle should be a dry, dead but sturdy branch about an inch thick, nice and straight, and about a foot long, maybe shorter. You can cut it to size with your knife, but it’s easier to find a piece of wood that’s already the right size. Shape it with your knife-rock until its a dowel thats rounded on one end, and pointy on the other.
Then from that same source, ideally, you’ll find your fireboard, which should be about two to three times as wide as the spindle and about a foot long. You’ll want to flatten one of the surfaces either by splitting the wood and abrading or scraping it until it’s kind of flat, or just chipping away with the knife-rock until you have a flat surface area. Prepare it by drilling out a hole that the pointy end of your spindle fits into. It doesn’t need to be deep, it just needs to fit. Then from the edge of the wood closest to the hole, you want to carve out a wedge shaped notch, this is where your ‘coal’ will form. I’ll find pictures to make this easier at some point.
The hold is what you’re going to use to brace the spindle, it can be a piece of hardwood or a rock that fits neatly in the palm of your hand, ideally it should have a depression in it that fits the rounded end of the spindle. You’re going to use this to hold the spindle in place as you work the bow.
Finally, the bow- You want to find a two to three foot long sturdy stick (about an inch thick) with a slight curve. That’s it, nothing special, just a strong stick. You should cut a small notch in the ends of the stick where you’ll be affixing your shoelace (or your homemade rope, or whatever). You might need to adjust the string a couple of times throughout the process, so make sure the knots are tight, but not so tight that you can’t quickly adjust them. It should look like a bow, because it’s a bow.
Now putting the whole thing together.
You want to grease the round end of the spindle, you can use your own gross body oil by rubbing the rounded end against the sides of your nose, where body oil lives. Don’t get your nasty nose grease the pointy end, or you’ll have to start over.
You’ll find yourself a piece of bone dry earth, or a nice slab of stone to work on. Place the fireboard on the ground, kneeling in front of it and holding the fireboard in place with one foot. In one hand, you’ll have your Hold, which should be gently resting on the spindle, that’s inserted into the groove in the fire board. Your bow string is looped once around the spindle.
Now, with the hold-arm braced against the shin of the foot that is clamping down on the fireboard, make sure that your spindle is perfectly vertical. You should be holding the bow at the end, and moving it forward and back in slow, controlled strokes so that you’re spinning the spindle. If we were both right up until this point, you have a working bow drill.