US Patent: 346,705
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| Micrometer Calipers
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Patentee:
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| Merrick M. Barnes (exact or similar names) - Boston, Suffolk County, MA |
| Manufacturer: |
| Not known to have been produced |
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Patent Dates:
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| Applied: |
Oct. 19, 1885 |
| Granted: |
Aug. 03, 1886 |
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Joel Havens
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Description: |
| "My invention relates particularly to improvements in such instruments, whereby is obtained a valuable increase in the accuracy and facility with which the amount of motion of the calipering-screw may be read; and the main object of my invention is to so construct the instrument, and especially those portions of it which show the extent of motion of the calipering-screw, that this may be read micrometrically and with increasing convenience upon a single scale, which scale may be divided regularly as, for example, to represent thousandths or arbitrarily as, for example, to represent divisions of the Stubbs, or Birmingham, or other arbitrary list of sizes. Heretofore it has been generally the custom in the case of micrometer-calipers to employ two scales; one by which to read the number of entire revolutions of the calipering-screw, the other by which to read the extent of a fractional or partial revolution. The number of complete revolutions has heretofore been read by noting the distance traveled by the calipering-screw in either direction past a scale. In this way the head of the calipering-screw, moving outward or inward, has itself served as the index or pointer to show actually, but not micrometrically, the extent of its own travel over the scale. The fractions of a turn have been measured micrometrically by graduating or dividing regularly a circle upon the periphery of the head of the calipering-screw, thus forming a moving scale, and noting the extent of travel of this graduated circle past a fixed pointer, commonly a "zero line", so called, drawn upon some fixed portion of the instrument past which the head of the calipering-screw moves. In each case, however, the head of the calipering-screw has itself served both as a scale for one reading and as a pointer for another reading. Calipers have also been devised in which the reading was done upon a single scale, as shown in Letters Patent No. 235,133, to S. Darling. The construction of this device, however, is such that, the scale being placed of necessity on the side of the instrument, the calipers cannot be read conveniently when held vertically, as is often necessary in calipering sheet metal. By my present improvement I have dispensed with the two scales and the double reading, partly actual and partly micrometric, and in their place I have substituted a single continuous graduated scale, upon which may be observed micrometrically and at one reading the total distance traveled by the measuring end of the calipering-screw. I also provide an index, the position of which upon the single continuously-graduated scale shows at a single reading the sum of the complete turns and fraction of a turn of the calipering-screw, in other words, the entire distance through which it is moved. Furthermore, by my present improvement I am enabled to locate the scale so that it may be easily read when the calipering-screw is held vertically as, for instance, in calipering sheets of metal plate." |
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