Precision Diameter Tapes

We offer a wide variety of tapes to meet specific diameter measuring needs. Our smallest diameter measuring tape measures diameters from .50” – 4.0” (15 mm – 100 mm) and our largest standard tape measures diameters from 144” – 156” (3600 mm – 3900 mm). Larger tapes are available on a special order basis.

Diameter tapes consist of 2 elements. A Gage member, and a Vernier member. All Gage members with the exception our 2 smaller tapes are approximately 48” long with 38 inches of engraved main scale (12” x 3.141592). The Vernier is about 6" to 8” long and contains the engraved Vernier scale. Diameter measurements are made by measuring the periphery of the object and matching the main scale to the Vernier scale. The Gage member and the Vernier member are offset so that the tape can be positioned exactly parallel to the object being measured to take an accurate measurement. The accuracy of our tapes are certified to be within +/- .001” (.03mm). Both the Vernier member and the offset Gage member are 1/4” wide. Material thickness is .006 for the small tapes and .010 for the larger tapes.

Our products come in both metric and standard scales. All tapes are made from an advanced Stainless Alloy that has physical properties similar to 1095 clock steel. All tapes are manufactured with processes that are non aggressive to the metal. No heat, chemicals, or other toxic materials are used thereby insuring the integrity of the tape. All tapes are temperature stabilized before the precision engraving of the gradients. The engraving is done in a controlled environment at 68F and 45% humidity.

Traditionally diameter tapes have been made from 1095 clock steel and 420 annealed stainless steel. The following is a comparison of the physical properties of the various materials:

Coefficient of Expansion per inch/degree F	1095 Clock Steel .0000063	420 Annealed Stainless .0000062	301HY Stainless .0000092
Elongation % in 2 inches (51 mm)	5% - 8%	29%	1.5% - 2.4%
Hardness – Rockwell B & C	RC 48 – 51	RB 88	RC 49 - 52
Tensile Strength in psi	260,000 – 290,000	70,000 – 80,000	270,000 – 300,000
Yield Strength	250,000 – 280,000	65,000 – 70,000	250,000 – 290,000

All products are issued factory certs traceable to N.I.S.T.

For customers requiring a higher level of certification, our tapes are sent to an accredited lab for calibration and certification traceable to N.I.S.T.

All tapes come with a lifetime warranty against breakage in normal use and material defects affecting the ability of the tapes to be recalibrated to specifications.