My comment - whoever coined the old adage "where there's smoke there's fire" obviously never worked with bow & drill!
Check out the Primitive Skills Group website for great info on the technicals of bow & drill. They discussed it in length about a year ago, including squaring, beveling, drill shapes, woods, fibers, etc. It might be available for viewing in their archives.
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Camine con tranquilidad, sirva con humildad, y viva en paz.