The Vermont Gage steel go and no-go gage set is a class X inch plug gage set for inspecting pitch diameter and functional threads of internally threaded parts. This tool is made from Rockwell c scale (Rc) cold stabilized steel for durability. It has a 2” handle with a threaded go plug on one end and a threaded no go plug on the other. A certificate of accuracy traceable to National Institute of Standards and Technology (NIST) is available for each gage, and each handle is marked with nominal size, threads per inch, class of fit, and pitch diameter. This gage set meets American National Standards Institute (ANSI) B1.2 standard for unified screw threads and is available in a range of sizes and thread fits for different applications.
Vermont inch gages have light blue handles to help avoid confusion with metric gages (that have yellow handles) during inspection. This inch gage set is available in a range of sizes followed by an abbreviation that indicates the type of thread to be inspected, including NPSM (National Pipe Straight Mechanical), UN (Unified), UNC (Unified Coarse), UNF (Unified Fine), or UNEF (Unified Extra Fine). This go and no go gage set can be ordered with a class fit of 2A (looser tolerance) or 3A (for a tighter tolerance).
Go and no-go plug gages are used to inspect the pitch diameter and functional thread for internally threaded parts to determine if they pass or fail tolerances (allowed deviation from the stated size). Go gages inspect form, lead, and pitch to ensure that the part being inspected is smaller than the maximum permitted pitch diameter and functional size, if the gage screws into the go plug gage it “passes”. No-go gages inspect pitch diameter and determine if a part is larger than the minimum size requirement by its inability or “failure” to screw into the threaded part (the part’s thread is too small). Go and no-go plug gages are used in conjunction to inspect the size and tolerance of threaded parts. They are available in different classes, based on acceptable tolerance (allowed deviation from the stated size as defined by ANSI B1.2 for unified inch screw threads). Standard tolerances and classes for gages up to .825” (20.96 mm) are as follows: Class XX (.00002" or .0005 mm), Class X (.00004" or .0010 mm), Class Y (.00007" or .0018 mm), Class Z (.0001" or .0025mm), and Class ZZ (.0002" or .0050 mm). For gages with a wider diameter, tolerance gradually increases for each class.
Vermont Precision Tools manufactures precision round and ground pins, perforators, and special punches. The company, founded in 1968 and headquartered in Swanton, VT, formed Vermont Gage division in 1980 to manufacture fixed limit gages. It meets ISO 9001:2000 standards.