US73279A - Improvement in bit-stocks - Google Patents

Description

NITED STATES A.A'rEN'r @Frio IMPROVEMENT IN BIT-STOCKS.

Specificationjbrming part of Leiters Patent No. 7 3,279, dated January 14, 1868.

To all whom it may concern:

Be it known that I, CHARLES H. AMIDoN, of Greenfield, in the county of Franklin and State of Massachusetts, have invented a new and useful Improvement in Bit-Stocks; and I do hereby declare the following to be a full, clear, and exact description of the same, ref erence being had to the accompanying drawings, in which- Figure l is a side view ot' the lower end of the bit-stock. Fig. 2 is a longitudinal section ofthe stock, showing thejaws in position,and the screw-nut or thiinble. Fig. 3 is a longitudinal section of thejaws. Fig. 4 is an end view of the same. Fig. 5 is a longitudinal section of-thejaws and screw-nut or thimble.

The object of this invention is to produce a bitstock which shall receive and hold any ordinary bit-shank firml y and rigidly, whatever may be its taper, and. without any tting .thereof whatever, and prevent any accidental withdrawal of said shank from its place and it consists, first, in the construction and use of two jaws, which conform to the taper of the bit-shank, and are forced equally upon `said shank at both ends by a screw-nnt or other device; second, in the special construction of the end of the bit-stock, to hold said jaws and retain them always in place; third, in the 'formation of the groove in the edge of each jaw, so that the shoulders of the bit-shank are inclosed, and the accidental withdrawal of the bit prevented; and, fourth, in the application and use of a spring, to prevent cramping of the jaws.

1n order that others may understand the construction and operation of my invention, I will more particularly describe it.

A is the bit-stock, constructed of metal or other suitable material, having at one end the ordinary swiveled head, and at the other the clamping mechanism which forms the subject of this invention, and which I will now describe.

That end ot' the bit-stock which receives the shank of the bit I will, for convenience, call the foot B, which is cylindrical, somewhat larger than the shaft of the stock, and has a male screw-thread cut upon its outer surface,

as shown in Fig. l.

The slot C is cut vertically through the foot B, from its end, as shown in Fig. 1, and within lt-his slot rest the jaws which seizeand hold `erant, as at a, and is then contracted toward the opening or mouth at that end, as shown clearlyinFig. 2. This thimble screws on to the foot B, and serves to force the jaws G G upon the shank of the bit. These jaws are constructed in the'form shown in Fig. 3, and

in thickness they are suitable to iill loosely vthe slot O.

At the lower ends of the jaws G G they are attached to each other by a. slightly curved wire, H, which is rigidly set in one part, and projects loosely through a corresponding hole in the other part. The upper and lower ends of the jaws are beveled, as at b and c, so that they may be forced toward each other by thc inclined surfaces ot' thethimble F and the l cavity D, when the said thimble is screwed on to the foot B, as shown in Fig. 2. In those surfaces of the jaws G G which are opposed to each other I form grooves e e, which, when the jaws are in position, form a recess of square section, as shown in Fig. 4.

This recess is made tapering, as shown in Fig. 2, so as to correspond with the taper ot' the bit-shank, and is largest just within the outer end, so that the shoulders of the bitshank may be inclosed within the cavity e, and the removal of the bit be prevented, except after relaxing the pressure of the jaws. As these jaws are loosely connected at the lower ends by the pin H, they may either move apart as on a pivot at that end, or they may be moved bodily away from each other, so as to accommodate a bit-shank of any size or taper within the capacity of the implement. These functions are clearly shown in Figs. 2 and 3.

The operation of this invention is extremely cach other by the outer end of the thimble.

This permits the jaws to conform to the taper ot' the bit-shank, and thereby grasp it rmly Y and closely throughout its length, which could not be the case it' thel jaws moved from any iixed point or center. As the thimble is forced upon the jaws with power the latter are compressed at their lower ends within the mouth of the cavity D, so that they cannot move laterally to the slightest extent, and the bearing and compression of the thimbleF and foot B through the screw-threads render the outer ends of the jaws equally rigid and immovable, and the bit-shank is held with great rmness and rigidity. The spring E serves to raise the jaws out otthe cavity D, when pressure is relaxed, so that they will not be liable to cranip or bind therein.

I am aware of the invention patented to WV. H. Barber, 24th May, 1864, and will designate some of the points of difference which exist between said invention and that presented in this patent:

First, Barbersj aws only touch the bitin front of the shoulders; my jaws grasp it throughout'the whole length ofthe tapered head, and without reference to the inclination `of the sides of said head.

Second, the bit-head enters a solid socket in Barbers stock; my stock has no socket except that formed by the movable jaws indented on their edges.

Third, in Barbers stock the head ot' the bit must exactly tit solid socket, or the jaws may close too far in front, or not at all, over the shoulders. In the rst case the bit would slip forward and would not be held steadily; in the second case the jaws might fail entirely to hold the bit.

Neither of. these events can happen with my stock, because any bit-head which can be inserted will be firmly grasped and held.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is- Y l. In combination with the jaws G G, or their equivalents, constructed to move away from or toward each other in the manner described, so that they may conform to the taper of the bit-shank, the screw-thimble F, or its equivalent,`to force the said jaws upon said shank, as and for the purpose set forth.

2. Thej aws G G, con structed'with the groove, formed substantially as set forth, so as to iuclose the taper sides and the shoulders oi' the shank, as and for the purpose described.

3. The cavity D, formed with a beveled orifice, as shown, in combination with the jaws G G, constructed with correspondingly beveled ends, as and for the purpose shown and den' scribed.

4. The spring E, located in the cavity D, in combination with the jawslG G, as and for the purpose set forth.

CHARLES H. AMIDON.

Witnesses:

L. J. GUNN, J. O. NEWTON.

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