External Variable Gages

TRI-ROLL External Thread Gage

This gage is ideally suited to thread measuring applications where the gage is to be dedicated to only one thread size or is used to measure a narrow range of sizes. This gage comes in a number of different frame sizes providing a total measurement range of #0-80 (M1.6) through 3⅜” (M85). Each frame size will cover 2 to 4 standard thread diameters in both inch and metric sizes. For example, the #4 frame size covers #10, #12, l/4″ and 5/16″ sizes. This design is best suited to manufacturing applications.

The TRI-ROLL Gage is a three roll, 120 degree contact position design. The following gaging roll types are available:

Thread CharacteristicRoll TypeANSI/ASME #
Functional Diameter (UNR)34.3
Functional Diameter (UNJ)3″J”4.3 Modified
Pitch Diameter (cone & vee)44.5
Minor DiameterMinor5.2
Lead & Flank AngleDifferential4.8
Runout (P.D. to major)Runout4.7

A different set of gaging rolls is required for each thread size to be measured.

TRI-ROLL Gages are set with Gage Class “W” single end, full form, threaded setting plugs. Users having ring gage setting plugs can use them if only the full formed section is used. For the greatest measuring accuracy always set the TRI-ROLL Gage using the calibrated size of the setting plug instead of the nominal size marked on its handle.

The result of a long form Gage Repeatability and Reproducibility Study of the TRI-ROLL Gage was 15% with functional diameter gaging rolls and 20% with pitch diameter gaging rolls.
TRI-ROLL Gages with Base, Frame and Electronic Indicator with S.P.C. output:
InchMetricSingle Frame Unit*
#0 thru #1M1TRU-100E
#2 thru #3M2 thru 2.5TRU-101E
#4 thru #8M3 thru M4TRU-102E
#10 thru 5/16M5 thru M6TRU-103E
3/8 thru 1/2M8 thru M12TRU-104E
9/16 thru 3/4M14 thru M16TRU-105E
7/8 thru 1-1/8M20 thru M24TRU-106E
1-1/4 thru 1-1/2M30 thru M38TRU-107E
1-5/8 thru 1-7/8M39 thru M47TRU-108E
2 thru 2-1/4M48 thru M56TRU-109E

*NOTE: Double Frame Unit, TRU-2XX, Triple Frame Unit, TRU-3XX

X-180 Segment External Thread Gage

The X-180 Gage is of the two-segment, 180 degree contact design. The single frame size covers #2 (M2) through 3/4″ (M 18).

This design can be used to measure functional diameter in all specifications and 180 degree circularity in ANSI/ASME System 23 and SAE AS8879 “Safety Critical” inspection. A different set of gaging segments is required to measure each thread size. The X-180 Gage can be changed from one size to another in less than one minute.

The use of the three roll or two segment gage design to measure functional diameter is optional in ANSI/ASME, SAE AS8879.

The result of a long form Gage Repeatability and Reproducibility Study for the X-180 Gage was 11 % for measuring functional diameter.

X-120 Adjustable Tri-Roll Thread Gage

The X-120 Gage is the same basic design as the TRI-ROLL Gage, having three rolls which contact the thread at 120 degrees apart. The differences are that the X-120 gage is much more widely adjustable and fewer gaging rolls are required because only one set of rolls is needed for each TPI (threads per inch). There are two gage frame sizes; small, #4 (M3) through 1″ (M24) and large, 1-1/8″ (M30) through 2″ (M50).

The thread size can be changed in less than three minutes by simply loosening four screws, adjusting the gaging roll axis pin position with a screw diameter template, retightening the four screws, attaching the gaging rolls, and setting the gage with the threaded setting master.

The X-120 Gage is best suited for use in incoming and final inspection. The following gaging rolls are available:

Thread CharacteristicANSI/ASME #
Functional Diameter4.3
Pitch Diameter (cone & vee)4.5
“VARIMINOR” (minor diameters 32 TPI & less)5.2 Variable

The “X-120” Gage is set with a Class “W”, single end, threaded plug gage.

The result of a long form Gage Repeatability and Reproducibility Study for the X-120 Gage was 17% with functional diameter gaging rolls and 25% with pitch diameter gaging rolls.

Our company is taking all precautions during the COVID-19 coronavirus pandemic. We remain OPEN for business and stand ready to serve you, although we are limiting customer interactions to PHONE and EMAIL ONLY at this time. Please continue to contact us either at 817-870-8888 or 800-435-2657.