Standoff: the axial distance between specified reference points on external and internal taper threaded members or gages when assembled with a specified torque or under specified conditions.
Non-B1.7 Expanded Explanation:
Stand-off is the test result received at the certification of a tapered screw thread gage. To certify a tapered screw thread working gauge it is tested against a tapered screw thread master gage. The two tapered screw thread gauges are screwed together until they lock-up (there is a procedure). A measurement is taken measuring the distance between a designated surfaces on the two tapered screw thread gages and reported as a stand-off. The perfect result of the stand-off is zero. Naturally there is a tolerance for the test result. The stand-off value may be either positive or negative; however; the most desired result is a positive amount nearing the positive tolerance working gauge limit because that will give you the most wear on the tapered screw thread working gage before it must be replaced. As the working gauge wears the stand-off value will change until it eventually exceeds the allowed tolerance; at which time the working gage must be replaced. It is important that when you get a stand-off certification on your tapered screw thread working gauge that you also receive a copy of the certification for the tapered screw thread master gage. No master gauge is prefect and like the working gage the master gauge is certified and has a stand-off. The tapered screw thread master gage is certified against a master-master gauge. The master-master gage is kept by NIST or some similar National Standards Registry. For full understanding of the data on a certification contact the calibration laboratory making the reports.
Original Posting: 3/20/2012
Last Revision: 8/14/2015
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