R1/2 thread: 20.96 mm × 14 TPI
Threads › R1/2
R1/2 is a BSPT taper (R / Rc) thread: 20.96 mm major diameter, 14 TPI (1.814 mm pitch), 55° form. Tap drill 18.25 mm. Taper thread: the Ø changes along the length, measure near the start.
| Standard | BSPT taper (R / Rc) |
|---|---|
| Major diameter | 20.955 mm (0.825″) |
| Pitch | 14 TPI (1.814 mm) |
| Thread angle | 55° |
| Tap drill | 18.25 mm |
Open R1/2 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
- G1/2Ø20.96 mm, 14 TPI
- 1/2-14 NPTØ21.34 mm, 14 TPI
- M20Ø20 mm, 2.5 mm pitch
- M20×1.5Ø20 mm, 1.5 mm pitch
- M20×2Ø20 mm, 2 mm pitch
- Tr20×4Ø20 mm, 4 mm pitch
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.