R3/8 thread: 16.66 mm × 19 TPI
Threads › R3/8
R3/8 is a BSPT taper (R / Rc) thread: 16.66 mm major diameter, 19 TPI (1.337 mm pitch), 55° form. Tap drill 14.75 mm. Taper thread: the Ø changes along the length, measure near the start.
| Standard | BSPT taper (R / Rc) |
|---|---|
| Major diameter | 16.662 mm (0.656″) |
| Pitch | 19 TPI (1.337 mm) |
| Thread angle | 55° |
| Tap drill | 14.75 mm |
Open R3/8 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
- G3/8Ø16.66 mm, 19 TPI
- 3/8-18 NPTØ17.15 mm, 18 TPI
- M16Ø16 mm, 2 mm pitch
- M16×1.5Ø16 mm, 1.5 mm pitch
- Tr16×4Ø16 mm, 4 mm pitch
- 5/8-11 UNCØ15.88 mm, 11 TPI
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.