I let local archeology "de-complicate" my fire drill. I've seen and handled dozens of drill boards dating back over several hundred years before contact and any chance of flint and steel. Those guys were good at it, and even with flint and steel, oral history sezz the drill worked better in local damp conditions.
Here's what history and archeology has taught me:
Local wood of choice for the drill board is cottonwood. They made their boards by splitting with a wedge, which left lengthwise grooves and ridges. There you have them- Lots of notches running lengthwise rather than crosswise. I remember one board about a foot long that had eleven burn holes in it. Lots of notches and lots of fires out of a single split board, and no whitlin.
Drills you find are consistently about as thick as my thumb and around 18" long. The ends are rounded, and the "fresh" ones I've seen appear to have been ground that way first before use against a rough rock or some such.
If sinew or hide weren't available for whatever reason, I bet they used spruce root for a string. I've tried it myself and it works just about as well as long as it's still green, wet and pliable, mostly for tying off each end to the bow.
I've always taken to the bow up here cuzz it does work better in the damp when you don't happen to have char along to "rescue" you from using local tinder sources with flint and steel. There's just a whole lot of other stuff that works well enough instead for tinder with a bow.
A guy doesn't even need a knife to do it. Use a rock to split your cottonwood, grind the ends of birch, alder or spruce limbs to round them a little, then use a bow from any of those plus a bit of spruce root, and you have the means to make a fire.
