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Drilling Long Holes

D

RILLING A LONG,ACCURATEhole, from edge to edge across the
width of a board, for example, is one of the few procedures in
woodworking that really requires assistance from jigs and guides.
To bore an accurate hole through the width of a plank, I make a
jig. If the drill-locating hole in the jig is accurately bored (a drill press
helps), I can’t miss. For this job, I prefer “aircraft bits,” which are long
twist drills with a shank that has the same diameter as the bit.
On the plank, mark the line you want the hole to follow and clamp
the guide bar parallel to it. Then clamp the jig against the guide bar as
shown, with the drill-bit holder against the edge of the plank, and
bore a shallow hole in the edge of the plank. Unclamp the jig, slide it
along the guide bar so that the drill-locating end moves away from the
edge of the board, and reclamp, keeping the jig against the guide bar.
Now, the drill bit will be supported farther back along its shank. Bore
halfway through the plank, then flip the jig end-for-end without
changing the position of the guide bar, and repeat the procedure on
the other edge of the board.
—MIKEPODMANICZKY,Thomaston, Maine,
from a question by Lazlo Spectrum,Tucson, Ariz.

CHAPTER FIVE

First position

Second position

Guide

bar

Drill

locating

hole.

Draw

centerline.

Drilling jig

Workpiece

Jig

Thickness

of plank

to be drilled