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G1/8 thread: 9.73 mm × 28 TPI

Threads › G1/8

G1/8 is a BSP parallel (G) thread: 9.73 mm major diameter, 28 TPI (0.907 mm pitch), 55° form. Tap drill 8.8 mm.

StandardBSP parallel (G)
Major diameter9.728 mm (0.383″)
Pitch28 TPI (0.907 mm)
Thread angle55°
Minor diameter, bolt8.57 mm
Minor diameter, nut8.57 mm
Tap drill8.8 mm
Usual classA bolt

Minor diameters worked out from the basic profile: major Ø − 1.28065 × pitch.

Open G1/8 in BenchsmithAdd to order list

Measure it

Bolt: Measure across the crests of the bolt with the caliper jaws. Worn bolts read 0.1 to 0.3 under.

Nut or tapped hole: Measure across the tops of the threads inside the nut or hole with the inside jaws. That is the minor Ø. Worn or oversize holes read a little over.

Close in size, won't mate

One size up or down

Got a bolt and no idea what it is? Measure the outside Ø and type it into Benchsmith → Find → Thread.