Functional Segments – Model BG: Engineered to replace both GO and NOT GO Thread Ring Gages, Model BG Functional Segments (180 degree contact) are the recommended and preferred design for the inspection of Maximum Material – Functional Size.  Unlike many alternate Variable Inspection Systems, the Functional Segment is fully capable of detecting variation in Flank Angle, Lead, Uniformity of Helix, 180 degree out-of-round, and insufficient Thread Root clearance.  Since any assembly problem is inevitably expensive and potentially embarrassing, the full helical path and profile of the Segments make the Segment design the obvious choice for the undisputed assessment of assembly.  Regardless of diameter, a minimum of 50% peripheral contact is always maintained.  Available in both standard AGD and special lengths of engagement, all Johnson Gage Segments are easily calibrated in the field with standard Truncated Master Thread Set Plugs.  If any wear beyond Class “X” Tolerance is apparent, requalification is always an option at a fraction of the original cost.

Functional Rolls – Model CGF – Engineered to supplement the GO Thread Ring Gage, Model CGF Functional Tri-Rolls are an alternative to the Functional Segment in some instances. While peripheral contact is limited to three distinct and equidistant 120 degree circumferential positions, the non-helical zero-lead Roll does not incorporate a full profile annular ridge into its basic design.  As the same set of Functional Rolls may be utilized for a variety of threads with identical TPI, the Functional Roll is an economic option for those instances where maintenance of both Variable and Attribute Thread data is desired.  Functional Rolls have also been successfully utilized for many threads with helix angles of less than 1’, circumstances where Helical Path Deviation or Elliptical Out-of-Roundness is not an issue, and situations where a Plain Cylindrical Setting surface is preferred.

Pitch Diameter Rolls – Model CN/PLT – With an axial contact less than one Pitch and .1P Flank Angle contact, Model CN/PLT Pitch Diameter Rolls are the preferred choice for the inspection of Minimum Material – Pitch Diameter Size.  Unlike alternative variable gage profiles and pitch micrometers, the simultaneous thread ridge and thread groove Cone and Vee contact completely eliminates the effect of Lead Error and Angle Error in the inspection of Pitch Diameter.  Distinct equidistant 120 degree gaging contact easily isolates elliptical and other add-lobed out-of-round conditions.

Minor Diameter Rolls – Model CN/MnD – While separate measurement of the minor diameter is not a general requirement for UN and Metric threads, UNJ and MJ threads require verification of the minor diameter. Johnson Gage model CN/MnD Diameter Rolls are an economical alternative to optical inspection for the evaluation of this critical characteristic.  A three pitch length of engagement guarantees adequate bearing surface for repeatable and reliable results, while a 5 degree thread flank relief assures clearance to and measurement of the minor diameter.

Lead/Angle Segments – Model BG/LA: Whether it’s a specification requirement or simply the desire to expand process knowledge, there are occasions when it is necessary to go beyond System 22 Thread inspection.  When that need arises, Model BG/LA Lead/Angle Segments are the ideal selection to provide variables data on the diameter equivalents of the variation of both Lead and Flank Angle.