US Patent: 434,460
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| Drill-chuck
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Patentee:
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| Charles T. Pratt (exact or similar names) - New Hartford, NY |
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Patent Dates:
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| Applied: |
Apr. 29, 1890 |
| Granted: |
Aug. 19, 1890 |
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Jeff Joslin
Vintage Machinery entry for Pratt Chuck Co.
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Description: |
| "My invention relates to drill-chucks; and the object of the improvement is particularly to provide means for giving positive rotation to the drill independently of the jaws of the chuck, whereby the strain on the jaws is diminished and their wear lessened. When the grip of the jaws on the drill is relied on alone to revolve the drill a great twisting and grinding strain is brought upon the jaws, by which they are unequally worn, and the accurate alignment of the drill in the chuck is rendered difficult or impossible. If, to obviate this, a socket for the end of the drill is made in the chuck for the purpose of imparting motion to the drill directly from the chuck and thereby relieving the strain on the jaws, then, should the end of the drill be formed out of true, the jaws cannot center the drill in the chuck without throwing the drill out of its true alignment in the axis of rotation. To overcome these difficulties, I insert a plate or piece, which has a slot to receive the end of the drill, in a chamber in the chuck in such a manner that the piece always is capable of a certain amount of motion in the chuck in a direction transverse to the axis of rotation. The piece revolves with the chuck, and by its engagement upon the end of the drill imparts positive rotation to the drill and relieves the strain upon the jaws. At the same time, should the end of the drill be out of true, then when the jaws are tightened on the drill the piece moves a little to the one side or the other and thus compensates for the want of trueness in the drill end, and thereby permits the jaws to accurately center and align the drill in the chuck." |
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