The bow drill is a fire-starting technique that every survivalist should know, and one that has been employed since the dawn of man. For those who aren't familiar, it consists of an upright drill shaft, a horizontal “bow” with a taut string, and a fire board with a divot and notch. As the bow is drawn back and forth, its string spins the shaft and generates friction against the divot, eventually producing a tiny ember that can be tipped out of the notch.
This fire-starting method may sound easy enough from the description, but anyone who has attempted the technique can tell you it's pretty tough in reality.
Although making a functional bow drill is difficult under any circumstances, it's especially tough when you're doing it the way our ancestors did: without any modern tools. Much like building a shelter is simple when you already have a tarp, paracord, a foam mat, and a sleeping bag, it's much simpler to make a bow drill with manmade resources. A sharp knife will make notching the board a quick task, and a strand of strong cordage will help produce a durable bow.
Unfortunately, if you already have a knife and cordage, it's likely that you also have a lighter, matches, or a ferro rod. In that case, you wouldn't need to make a bow drill. So it's much more realistic to test your bow drill skills without these modern items, in case you find yourself in a similar circumstance someday.
YouTube survivalist NW Primate recently tried his hand at making stone age fire with only primitive tools and natural cordage. The results of this video show just how challenging it can be when you don't even have a cutting tool:
The takeaways are twofold — first, recognize that starting a fire this way is almost guaranteed to be a test of your patience, so embrace the challenge and don't give up. Second, always make a point to bring several basic fire-starting tools (even if that means wearing a neck knife with a FireCord lanyard and a ferro rod) so you won't need to resort to chopping wood with rocks.