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Three Wire thread Measuring Systems from Thread Check Inc

three wire thread measuring systemThe traditional three-wire method is the most accurate method of measuring the effective or pitch diameter of an external screw thread. Unfortunately in the past, holding and correctly positioning three wires against a thread while simultaneously taking an accurate measurement had been an extremely difficult task. Now, Thread Check's 3-Wire Thread Measuring System provides a simple and precise way for determining the pitch diameter for threaded parts and thread plug gages. The system enhances Repeatability and Reproducibility ( R & R ) and reduces measurement time to a fraction of the time normally taken using the traditional three-wire method. Thread Check offers specially designed wire holders and wires and base assemblies that make thread measurement fast and accurate. Thread Check's holders are fitted with certified full length thread measuring wires that meet or exceed the requirements of the ASME/ANSI B1.2, and B1.16M, thread standards as well as ASME B89.1.17-2001, Federal Spec. GGG-W-366b and ISO standards. All wire holder sets include the actual wire size, NIST traceable number, and the constant required for determining the pitch diameter.

Thread measuring holders are precision made to predetermined thread pitches. The wires are held in a predetermined position by light pressure clips. The holders rotate freely on the spindle/anvil of the measuring instrument so as to engage the lead angle of a thread. Holders can be purchased without wires for companies that have existing wires. Wires can be easily installed. Thread measuring holders are available in a full range of Standard, Metric, and Acme sizes. Thread Check's engineering department can design wire holders for multiple start threads, helical gears, worms, and other special thread measurement applications. Thread measuring holders and wires available for a wide selection of measuring instruments.


  • Certify working thread plug gages & setplug gages
  • Monitor the wear on working thread plug gages
  • Monitor and control pitch diameter variation during thread fabrication
  • Use in conjunction with “GO” and “NOGO” ring gages to control thread size to the most demanding specifications
  • Determine out of roundness and taper that may exist in threaded parts
  • Applications for preplating & postplating thread measurement
  • Eliminate the cost and time involved in using outside calibration services
  • Reduce measurement time to a fraction of the time normally taken using the traditional three-wire method.

PATENT NO. 5,317,809
PATENT NO. 5,383,286


The Three Wire Method

The three wire method is recommended for universal use in the direct measurement of thread gages and components. It has been found to be the most accepatble and universally recognized method of measuring pitch diameter.

The pitch diameter is the diameter where the thread thickness is equal to the space between the threads. If the flats at the top and the bottom of the thread are the same, the pict diameter will coincide with the middle of the sloping side of the thread.

The pitch diameter is represented by the letter E
E=D - depth of thread = D - h