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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