Drilling Long Holes With Gun Drills
Chris Becksvoort’s answer to the long-hole end-grain drilling question (Fine Woodworking #116, p. 26) is right on target for woodworkers who do this occasionally. But if you are doing production drilling of long holes, a gun drill is the way to go. Gun drills are special bits made for drilling steel gun barrels. They are available in several lengths and diameters useful to woodworkers. One source is Danjon Manufacturing Corporation (1075 S. Main St., P.O. Box 212, Cheshire, CT 06410-0212; 203-272-7258).
The cutting edge of the gun drill uses a scraping action that will not wander in end grain. The most useful feature of the gun drill, however, is a hollow shank that permits the flow of pressurized air into the cutting area. The flow of air flushes out chips, allowing uninterrupted boring of smooth, precise holes.
I hold the drill shank in a carriage that slides on the lathe ways. The bit goes through a special hollow in the tailstock, dead center into the wood. I pump 100 psi pressure into the drill, and use a steady rest made by Andrew Shimanoff Tool Design (P.O. Box 1318, Ashland, OR 97520; 514-488-3059) to support the blank on the outboard end. With this setup, I can bore a 3/16-in.-dia., 15-in.-long hole in extremely hard wood, like African blackwood, in about 90 seconds. The bits are expensive, but drilling holes does not get any faster or more accurate than this.
Michael A. Dow, York, Maine
Fine Woodworking Magazine, October 1996 No. 120
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