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In my last article, I discussed the introduction of Stanley's 100 Plus line of screwdrivers. Although based on Christian Bodmer's patent of 16 July 1929, the 100 Plus screwdrivers used only part of Bodmer's patent-the outside ferrule and the insulating washer. Bodmer's patent for the bolster provided for a knurled shank, which was driven under pressure into the bolster. Apparently, tests showed that under severe usage this was not substantial enough.
Harris Cook, another inventor at Stanley, patented an improvement (Figure 1) on Bodmer's patent by forming four wings and grooves on the shank, which was then driven into the bolster. The bolster had two rings formed on it. These rings lined up to the grooves of the shank when the bolster was inserted into it. After the shank was driven into the bolster, the bolster was placed into a die that squeezed the rings into the grooves and wings of the shank. It also placed four ribs on the outside of the bolster. The shank and bolster were next inserted with an insulating washer into the handle and ferrule and driven tight, thereby preventing axial movement between shank, bolster and handle. Beginning in 1934, this new bolster-type construction was used on upgraded no. 25, 45, and 55 screwdrivers.
The Hurwood bolster-type construction no. 25 screwdriver featured a standard tip (Figures 2 and 3) and was available in 2 1/2-, 3-, 4-, 5-, 6-, 8-, 10-, and 12-- inch blade lengths. This type screwdriver was also manufactured with a parallel-sided cabinet tip (Figure 4) in 11/2-, 2 1/2-, 3-, 4-, 5-, 6-, 8-, 10-, and 12-inch blades. Cabinet tips are parallel-sided blades that do not flare out at the tip and are the same diameter throughout the shank.
A light duty, small blade, bolster-type screwdriver -designated no. 55-was made for electrical work and for small screws. This screwdriver had a smaller standard tip with a 3/16-inch diameter blade and was produced in lengths 1 1/2 to 12 inches.
The Bell Telephone Company was quick to see the quality of this type of screwdriver and had Stanley manufacture for them a special screwdriver with a 3 1/2-inch blade, 1/ 8-inch diameter shank, and a cabinet tip. These screwdrivers were marked KS 6854 and Bell System (Figure...