Auger and Brace

Hands off the pressure and let the thread work.

1. Start an auger bit in a board and turn it steadily with almost no downward force.
2. Count turns and measure the depth reached.
3. Divide to get millimetres per revolution.

Compare a spurred bit against one without.

1. Bore a hole with an auger bit that has scoring spurs.
2. Bore another with a plain twist drill of the same diameter.
3. Compare the rims, especially across the grain.

The brace's crank offset is a lever arm and it is chosen, not incidental.

1. Measure the sweep — the diameter of the circle your hand travels.
2. Bore a large hole and note the effort.
3. If you have two braces of different sweep, compare them on the same bit.

The exit side is where hand-bored holes are ruined.

1. Bore until the lead screw's point just breaks through the far face.
2. Stop, withdraw, and finish the hole from the OTHER side.
3. Alternatively clamp a sacrificial backing board and bore straight through.

The brace appears in Europe in the fifteenth century — one is visible in Flemish painting of the period — and is one of the earliest applications of the continuous crank to a hand tool. Before it, holes were bored with a T-handled auger turned in half-turns, or with a bow drill that reverses direction every stroke. A crank turns continuously in one direction, which suits a lead screw perfectly.

Russell Jennings patented the double-twist auger bit pattern in the mid nineteenth century, and the Jennings and Irwin patterns became the standards — Jennings with a fine double spiral for clean holes in hard wood, Irwin with a coarse single twist that clears waste faster in soft wood. Both are still made, and the choice between them is still made on the same grounds.

The ratchet brace was the significant refinement: a pawl mechanism lets the operator swing the crank back and forth through a partial arc in a corner where a full rotation is impossible. It is the reason a brace can bore a hole in a joist between two walls.

Not obsolete, just displaced. A cordless drill is faster in every ordinary case. A brace still wins where there is no power, where the hole is very large and the torque needed exceeds a light drill, where control matters more than speed — and in timber framing, where boring a clean 25 mm peg hole through a beam by feel is genuinely easier by hand than fighting a heavy powered auger.