New Spiral Screw-Driver - Carpentry & Building, Vol.6, 1884

The Decatur Coffin Company, of Decatur, Ill., are introducing a new spiral screw-driver, the general appearance of which, with the bit withdrawn, is shown in Fig. 12 of the engraving.

The rotary motion of this tool is obtained by two spiral grooves cut on the inside of the brass cylinder which form the shank. A sleeve with corresponding spiral projections fits loosely upon the upper end of the bit and inside of the cylinder.

On the lower edge of the sleeve notches are cut, into which fits a pin that extends through the bit near the upper end. Whenever pressure is applied to the bit this pin engages in the notches in the sleeve, so that forcing the bit into the handle causes the bit to be rotated.

Accordingly, by placing the end of the bit in the head of a screw and pushing the screw-driver against it the screw will be driven home.

The manufacturers claim for this device simplicity of parts and thoroughness of construction. By providing the spiral groove in the shank of the tool the bit is left of full size, and therefore must be stronger than those of equal diameter which are cut away in order to obtain a construction which will impact a rotary motion under pressure.

The sample which we have received, with the bit withdrawn, as shown in the engraving, is a little over 12 inches in length. When the bit is extended to its utmost capacity, it measures a trifle over 19 inches.

Patent 306,096 - 10/07/1884 - Screw Driver by Christopher H. Olson