7/8 BSW thread: 22.23 mm × 9 TPI

Threads › 7/8 BSW

7/8 BSW is a BSW Whitworth thread: 22.23 mm major diameter, 9 TPI (2.822 mm pitch), 55° form. Tap drill 19.25 mm.

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

Open 7/8 BSW 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.

Same diameter, other pitch

• 7/8-9 UNC9 TPI (2.822 mm pitch)
• 7/8-14 UNF14 TPI (1.814 mm pitch)

Close in size, won't mate

• 7/8-6 ACMEØ22.23 mm, 6 TPI
• M22Ø22 mm, 2.5 mm pitch
• M22×1.5Ø22 mm, 1.5 mm pitch
• Tr22×5Ø22 mm, 5 mm pitch
• G5/8Ø22.91 mm, 14 TPI
• 1/2-14 NPTØ21.34 mm, 14 TPI

One size up or down

• 3/4 BSWØ19.05 mm (down)
• 1 BSWØ25.4 mm (up)

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