Gage Block and Pin Gauge Basics

Important specifications to consider for gage blocksinclude block size, set range, set steps or increments and tolerance grade. Gage block size is the thickness, diameter, length or other dimension of thedimensional standard.  Set range is the total length or dimensionalrange that the set of gage blocks can measure.  Set steps are thedimensional size increments or steps in a set of gage blocks or otherdimensional standards. 

Tolerance grade can be Grade 0.5 (Lab Master orAAA), 1 (AA), 2 (A1/A+), or 3 (A).  Federal Grade 0.5, GradeAAA, or Laboratory Master Grade products provide the highestdegree of accuracy and are used in precision or master calibration gagingoperations in temperature controlled metrology or standards laboratories. Grade 0.5 gage blocks under one inch in length should have length tolerances of+/- 1 micro-inches (1 mike or 1 millionth of an inch) and flatness andparallelism variation of not more than 1 micro-inches. Federal Grade0.5 exceeds German Grade 00 as well as DIN, ISO, and BSS Grade K. 

Federal Grade 1, Grade AA, or LaboratoryGrade products provide a high degree of accuracy and are used inprecision gage checking or setting operations in qualitycontrol or metrology laboratories.  Grade 1 gage blocksunder one inch in length should have length tolerances of +/- 2micro-inches (2 mikes or 2 millionths of an inch) and flatness andparallelism variation of not more than 2 micro-inches. FederalGrade 1 exceeds German Grade 00. as well as DIN, ISO, and BSS GradeK. 

Federal Grade 2 or Grade Aor Inspection Grade products provide a high degree ofaccuracy and are used in precision gage checking orsetting operations in quality control ormetrology laboratories.  Grade A+ block indicates a manufacturer thatprovides higher level or precision compared to the government Grade Astandards.  Grade gage blocks under one inch in length should havelength tolerances of +/- 2 micro-inches (2 mikes or 2 millionths ofan inch) and flatness and parallelism variation of not morethan 2 micro-inches. Federal Grade 2 exceeds German, DIN, ISO, andBSS Grade 0 standards. 

Grade A,or Inspection Grade, products provide sufficient accuracyfor use in gaging, setting and general inspection operations inproduction or tool room areas.

Features common to gage blocks include markingcapability and NIST traceability.  Gages that accommodate a scribe orother device for accurately marking a component at a specificmeasurement along a particular dimension have markingcapability.  A gage that is NIST traceable gage has been compared to amaster standard that has been checked against a NIST standard.

A gage pin is a two inch cylindrical pinthat is often used along with the sine bar to help to determine a range ofprecise measurements.  A gage pinis able to provide an easily accessible surface and a known height which can beused to measure hole size and depth, check distance between holes, GO, NOGOgaging and for setting micrometers.  Moresimply, a gage pin or pin gauge as they are also called, helps a person measurewithin a specific range of measurements to help ensure that parts meet specificdesign tolerances. WESTport Corporation has taken the extra step for a betterpin gage by replacing the Class ZZ gage pin with the Class Z gage pin. Itprovides a closer tolerance (.0001) providing more accuracy for your inspectionprogram. A gage pin is available individually or in different size sets to suitwhatever your inspection needs call for.

What are Gage Blocks?

Gage blocks also known as gauge blocks are manufacturedto precise gage-maker tolerance grades for calibrating, checking, and settingfixed and comparative gages.  Rectangular, square, wear, scribing andangle gage blocks are available in hardened steel, carbide and ceramicmaterials.  Tolerance grades range from Lab Master or Grade 0.5(AAA) blocks with +/- 1 micro-inch tolerances for standardslaboratories to the lower inspection or working Grade 3(A) blocks for gaging, setting and general inspection operationsin production or tool room areas.  Other proprietary blocks may beavailable for specific applications with higher or lower tolerances and configurations.Types of gageblocks include angle, square, rectangular, and wear.  Square gageblocks do not have a central hole and are held together with an external gageblock holder.  Rectangular gage blocks have one or more centrallylocated holes for mounting on holding bars.

What is a Gage PinUsed For?

Anytime a cylindrical hole needs to bemeasured to very close tolerances a pin gauge or gage pin may be used.  A pin gauge is pre-measured and the specificsize that correlates with your design's specifications may be used to determinewhether the hole or opening is within the design tolerances that areallowed.  This is vital for many types ofproducts such as for pneumatic systems where specific openings can be used to adjustair flow and precision is needed in creating the parts.  A gage pin or pin gauge makes measuring aneasy part of the process that can be completed in mere seconds.

What is a Gage Block Used For?