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Boring Tools and their Makers

  Knudsenís Bit Brace - English Mechanic and World of Science - Vol.56, 1893

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The brace shown in the illustration has a readily attachable and detachable knob, with an easy bearing and excluding dust and dirt, an extensible and adjustable crank, a convenient and easy handle, an improved ratchet connection between the brace-crank and the bit-shank, with a new and efficient means of fastening bits of various sizes to the brace, and other novel features, says the Scientific American.

The improvement has been patented by Mr. Andrew Knudsen, of Tucson, Arizona Territory.

Fig. 1 shows the device in perspective

Fig. 2 being a sectional view of the knob

Fig. 3 a section of the jaw-holding and adjusting mechanism

Figs. 1 and 5 showing the ratchet mechanism

Fig. 6 illustrating the bit-holding and adjusting mechanism

The bearing knob is socketed on its inner side and screwed to the reduced end of a screw-cup or nipple, which has a socket to receive the bearing cone of the brace stem, extending through a tubs.

The two crank arms each comprise two members, one adapted to slide within the other, the parts being held together in desired position by thumb screws, the arrangement being such that by pushing the members well in, the brace may be turned in small space, where but little power is required, while by pulling out the members, greater leverage is obtained.

The crank handle has au inner two-part tube, the parts of the handle being hinged together and having overlapping portions, spring - pressed pins within, the handle projecting through the overlapping parts, the pins being pressed inward when the handle is to be removed. The lower end of one of the members of the lower crank arm terminates in a cylinder which turns on the ratchet head formed integral with the bit-holding shank, the rotation of which in either direction is provided for by a simple pawl and ratchet arrangement.

A screw extending longitudinally through the ratchet head has at its upper end a turning knob, by means of which the outer ends of the jaws may be forced together or allowed to spread apart, enabling the jaws to be clasped firmly to a bit, and be very quickly adjusted.  Each end of the jaws fits several sizes of bits, and by reversing the jaws they may be made to fit many sizes, several pairs of jaws being preferably provided for each brace.

The invention is designed to improve the entire construction of a bit brace, that it may be easily adjusted, efficiently operated, and nicely and strongly finished.

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Yankee Braces


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