ANSI Y14.5 – 2009, Dimensioning and Tolerancing, Section 2.9, states that “each tolerance of orientation and datum reference for a screw thread applies to the axis of the thread derived from the pitch cylinder." The Positional Tolerance Method (Section 188.8.131.52) states that the pitch cylinder is the default condition. The JO-PLUG® solid thread form provides a calibrated pitch diameter, coaxial and concentric to the stem. Compared to other methods, which do not reference the pitch cylinder, Precision JO-PLUGS® are preferred by blue-chip Quality professionals.
Precision JO-PLUGS® provide positive Quality results with repeatability and reproducibility to our satisfied customers in a wide range of industries. Used in conjunction with a CMM or Laser Tracker, basic position and orientation are established quickly and accurately. Projected tolerance zones and perpendicularity are also measured.
In addition to off-the-shelf Precision JO-PLUGS®, Spence Industries, Inc. specializes in the manufacture of custom gages for unique applications: extended projected tolerance zones, tapped holes below counterbores, tapered pitch diameter threads, and other particular customer requests.
- Certificate of Compliance at no charge with every order
Precision JO-PLUG® pitch diameters are calibrated using a Pratt & Whitney Super Mic utilizing the universal "three wire method."
Precision JO-PLUG® "lead and trail" thread angles are verified using a J&L Metrology Optical Comparator.