Show BORING SQUARE HOLES perhaps the reason that so many square pegs are fitted into round holes is the difficulty of making square ones the method heretofore has been to bore round holes and then work them out by hand or with a ta a laborious and time consuming operation to bore square holes sounds paradoxical nevertheless it is done and that with a three cornered bit the three cornered bit has of course something besides a purely rotary motion about a fixed axis and that is the interesting point about the appliance ance the peculiar motion by which the three cornered drill is made to bore a square ho hole le is imparted to it by a special chuck which can be fitted upon any ordinary drill press lathe or milling machine this chuck consists of a few simple parts one of which is screwed directly onto the spindle of the machine while another part driven by it receives the rotary motion with a certain amount of side play the side play being limited and guided by the third part of the chuck which stands still the shank of the drill is three cornered with convex sides and is just large enough to turn in the square guide of the stationary part of the chuch the result is that the three corners of the shank travel around the sides and enter into the corners of the guide while at the same time the three corners comers of the cutting edges of the tool strike out a square in the work the result is highly successful as the new tool can be used for boring square holes in cast iron steel brass or wood and with the same facility and a speed almost equal to that with which a round hole can be bored we have recently had the pleasure of inspecting spec ting the tool in action and must say that the work is done quickly neatly and accurately the chuck and the tool can be examined at the show rooms of the radical angular drill company liberty street new new york city we are advised that the selling price of the tool will be very reasonable which will doubtless secure a wide adoption of it in this country such as it has already received in Ger germany miny where it is used in considerable numbers by such firms as Fr freidrich eldrich krupp siemens balske etc |