Complete 18th century Cabinetmakers Tools and Box

I can see were a larger spade bit could be re-worked. One thing that could be a problem I feel would be the thickness of the bit in terms of the contact area of the horn or bone. I'd imagine the period tools were more stout which to me would lend to more contact of the cutting area on the stock. This increased surface area would probably cut down on vibration and chatter. However being used with a brace by hand that decreased area may not pose much of a problem.

I can certainly see were those spurs would be needed. I also wonder what angle would be required on the cutting edge... To shallow no good, to steep no good! Trial and error at it's best here.