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Hand tools Metalworking
Woodworking Moretofollow |
American standard for copper wire
Birmingham and the stubbs gages for iron wireThe English standard gage is the Birmingham or Stubbs gage. It is also used widely in the United States. The Birmingham gage resembles the American Standard Wire Gage. It is generally used for the measurement of iron wire, although it is sometimes used as a sheet-copper gage. The numbers on this gage range from 6 to 36. Use of wire gagesTo gage a wire, insert it in one hole of the proper gage after another until you find the hole it just fits in. The number of that hole gives you the gage number of the wire. Efforts are now being made to reduce the number of standards used in wire gages. In the meantime, many engineers in designing machinery ignore the gage numbers and specify all wire diameters in decimals of an inch. To meet the condition, circular gages are made with the number or letter size marked on one side of the gage and the decimal equivalent marked on the other. A further complication enters when parts must be matched with dimensions given in the metric system. This requires calculation of each dimension or the use of the metric conversion table. The V-GageFigure shows a gage with a V-opening. This type of gage may be obtained calibrated in gage numbers, decimals, and various combinations of units. In use, the wire, screw, or rod being measured is allowed to rest lightly in the groove and the gage marking at the point of contact indicates its size. In using any of these gages, it is obvious that the accuracy of the reading is dependent upon how closely the part measured fits the gage.
If a gage is accidentally damaged in a way to affect its accuracy, it should be destroyed or, if the cost justifies it, it may be returned to the manufacturer for recalibration. If it is left available, its use while damaged may lead to errors, costly in waste of material and time. Sheet metal gage
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