THE ordinary marking gage fitted with a pin to mark a piece of work is open to the objection that the pin is liable to follow the grain, especially in hard wood, giving an untrue line. The marking gage may be improved by substituting a steel disk roller for the pin. A small projection of wood may be secured to A rotary marking gage. the body of the gage and upon this a steel disk about three-quarters of an inch in diameter may be fastened with a small screw, permitting the disk to rotate easily upon the body of the screw. In use the disk will mark a true line regardless of the grain of the wood. Improvement for Screwdrivers PICTURED in the accompanying drawing is a very simple device which will be found useful on small screwdrivers. It consists of a swivel head secured to the upper end of the screwdriver and serving as a rest for the palm of the hand. The shank of the screw- Screwdriver with swiveled palm rest. driver is fitted with a handle in the shape of a ball, secured by means of a transverse pin. This may be turned readily by means of thumb and finger while the palm of the hand is resting upon the swivel head and holding the screwdriver firmly in place.
This article was originally published with the title "Rotary Marking Gage" in Scientific American 105, 26, 580 (December 1911)