Pitch Diameter Gage Operation Manual
Models MRP 1500/2500/3500
Copyright © 2018 Gagemaker. All rights reserved
60
Rod Style Setting Standard Correction Factors
Pivot Shoe Compensation Factor
The shoe compensation factor compensates for the change in diameter of the pivot shoe
between setting to a square standard and measuring to a tapered thread. The diagram below
illustrates the change and how to adjust the setting standard to compensate for the change.
Step Thread Compensation
Step type threads are threads that have roots and crests that are parallel to the center line of the pipe. When
measuring connectors with step threads, a compensation must be made for positioning of the pivot shoe across the
thread’s stab flank crest radii. The diagram below illustrates how the step thread compensation factor is determined
and how to adjust setting standards to compensate for the shoe contact.
Total Correction Factor
The total correction factor is the combination of the shoe compensation factor and step thread compensation
factors. This factor applies only to tapered thread connectors that have a step type thread form. Buttress
connectors that are 16” and larger and many premium connectors require the total correction factor. The factor is
added to pin calculations and subtracted from box calculations.
α
Half thread taper
β
Stab flank angle
H P.D. to crest
P Lead
R Stab flank radius
A tooth width (p/4)
Rs Center of shoe to contact surface
B = H + A * tan
α
-R
C = B* tan
β
D = R/cos
β
E = A - C – D
K = R/cos
α
- R
L = E * tan
α
Comp factor = 2 * (K + L )
α
Half thread taper
Rs Center of shoe to contact surface
Shoe comp factor = Rs * ((1/cos
α
)-1)