Manufactured by Spence Industries, Inc., Precision JO-PLUGS®, are designed to determine Basic Position and Basic Profile of threaded holes. The location and orientation of tapped holes is derived using the pitch cylinder axis of the threaded hole in accordance to ANSI/ASME Y14.5 M – 2015. Significant to the Spence Industries, Inc. optimal design is the solid thread form with a pitch diameter that is calibrated, front and back, using the universal three-wire method. The JO-PLUG® centerline location plug pitch diameter cylinder is coaxial to the cylindrical “stem” of the gage, establishing a parallel datum axis within which MMC is established. Basic Position and Basic Profile dimensions, which define the orientation and location of the related tolerance zones, are established using CMM or Laser Tracker software. True position of the tapped hole, as well as perpendicularity and projected tolerance zone of the threaded hole is established.
JO-PLUGS® are threaded and inspected in accordance with the International Standard ISO/IEC 17025:2005, which meets the general requirements for the competence of testing and calibration laboratories. This laboratory also meets the requirements of ANSI/NCSL Z540-1-1994 and any additional requirements in the field of calibration.
Precision JO-PLUGS(R) are calibrated using the Pratt & Whitney Super Mic utilizing the “three wire method” and thread angles are verified using the J & L Metrology Optical Comparator. The pitch diameter is critical in determining tolerance of orientation or position datum reference of threaded holes.
Spence Industries, Inc. specializes in “quick turn-around” for the manufacture of Precision JO-PLUG® centerline location plugs made “to print” to meet unique manufacturing and inspection requirements. Any coarse or extra fine thread true position locator can be manufactured, in any thread form, and we have made “specials” ranging from “0” to 7.5” thread diameter.