SPI 23-187-8 PD:0.5644 5/8-11 UNC 2A Go Adjustable Thread Ring Gage

This is a new SPI (Swiss Precision Instruments) adjustable Go thread ring gage, part number 23-187-8, sized for 5/8-11 UNC external threads to Class 2A fit tolerance per ANSI/ASME B1.2. The Go member checks the maximum material condition of the external thread — a bolt or stud that passes through this ring without interference is confirmed within the upper pitch diameter limit; the stamped pitch diameter is 0.5644 in, confirmed directly on the face of the gage and on the included Certificate of Inspection (Cert. No. 309257, Serial No. SFM 2633). The certificate is traceable to NIST (vide 21-53922-B), dated 13-03-2024, with a specified pitch diameter of 0.5644 −0.0003 in, minor diameter 0.5250 −0.0006 in, and major diameter cleared; the gage was set on a set plug (Sr. No. PMF 10413) and verified OK with a plain check plug per ANSI/ASME B1.2. The ring body is hardened tool steel with a knurled OD for grip, features three spanner wrench holes for adjustment locking, and is supplied in its original anti-corrosion bag with desiccant beads and a plastic storage case — standard SPI packaging indicating an unused, calibrated instrument ready for immediate production or inspection use.

Product Specifications