Page:Popular Science Monthly Volume 88.djvu/799

 A Bow-Drill for the Work-Shop

HE bow-drill about to be de- bear directly on the end of the chuck.

��I scribed will be found a most use- ful addition to the average ama- teur's workbench, and although the size of the drills somewhat restrict its field of usefulness, it will be found invaluable in the construction of certain classes of apparatus.

The handle should be turned first, preferably from good ash stock. It is perfectly straight in di- ameter and 5^/4 inches long. One end tapers in to % inch. A %-inch hole should be bored in the other end 3% inches deep; this serves as a mag- azine for the drills.

The next step is to turn the knob or breast-piece. This is 2 inches long and 1 14 inches at the widest point. One end is rounded off as shown in the dia- gram, while a shank % inch long and % inch in diam- eter is turned on the other end. This fits the maga- zine and serves as a stop for it and as a breast- piece for the drill.

The next step is turning the spool, the dimensions of which are given in Figs. I and 3 of the diagram.

The chuck is next made. This is of iron or soft steel Va. inch in diameter and 1% inches long. A slot 1/4 inch long is filed in one

��This reduces the friction.

The next step is to embed the steel spindle in the handle. This had best be of steel, j4 inch in diameter and 2}i

���Construction details of a bow-drill adapted for actual workshop use

��side 1/4 inch from the end ; the upper inches long. One end should be slightly side being filed 11/64 inches deep, rounded, while the other is tightly em- while the lower side is filed 5/64 inch bedded in the handle for % inch of its deep. A hole is next bored end- length. The spool on this spindle should ways into this slot slightly larger than rotate freely.

3/32 inch ; the other end is embedded The drills are next made and are eas-

into the end of the spool for one inch of ily and cheaply constructed from the

its length and should not turn. A 9/32- ribs of an old-fashioned umbrella,

inch hole should be bored in the other These ribs are of the finest spring steel,

end of the spool up to the end of the To make the point, cut the wire to the

chuck. This should be done before the desired length, say about 3 inches, as

chuck is put in so that the spindle will this is long enough for average work.

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