Precision JO-PLUGS® are available from stock in Unified, Metric, and Heli-Coil thread sizes for immediate delivery. Spence Industries, Inc. specializes in the manufacture of custom threaded gages for unique applications. We are capable of manufacturing Precision JO-PLUGS® to a high standard of quality from your napkin sketch or electronic design.

  • C of C traceable to NIST and ISO/IEC 17025:2017 and ANSI/NCSL Z540-1-1994 Accreditation at no charge with every order
  • Unified Series pitch diameters are “Go Basic,” suitable for Classes 2B and 3B
  • Fast delivery: unified, metric and Heli-Coil® series threads
  • Quick turn-around on custom manufacture JO-PLUGS®

ANSI /ASME Y14.5M - 2018, 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 declares that the pitch cylinder is the default condition. The JO-PLUG® solid thread form provides a calibrated pitch cylinder, coaxial and concentric to the spindle diameter of the JO-PLUG® . In conjunction with a CMM or Laser Tracker,  basic position and orientation are quickly and accurately  established. 


Extended projected tolerance zones, tapped holes below counterbores, tapered pitch diameters for irregular surfaces, UNEF, and other non-common thread forms are examples of custom JO-PLUGS® manufactured for unique applications.


Spence Industries, Inc. is proud to be enrolled assisting United States government facilities make exceptional products.

Please use this form to request information or call our HOTLINE (586) 758-3800 for immediate assistance. We will be glad to answer questions on in-stock items or offer our expertise with unique inspection requirements.

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