ISO 8737 is the standard cited for taper pins with external thread, unhardened. This page sets out what the standard controls for this part, reproduces the dimensional table supplied against it, and notes the related designations referenced on drawings.
ISO 8737 — Scope
ISO 8737 is "Taper pins with external thread, unhardened". Taper 1:50.
Tolerance & Product Grades
ISO 8737 does not divide taper pins with external thread, unhardened into product grades. Tolerances are given as limits on the individual dimensions in the table.
Where a general-tolerance class is cited on the drawing instead, it applies to the dimensions not otherwise toleranced.
Dimensions Specified by ISO 8737
| Nominal diameter d (mm) | d_1 (mm) | a (mm) | b (mm) | d_2 (mm) | Pitch P (mm) | d_3 (mm) | z (mm) | Length range l (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|
| 5 mm | 5 | 2.4 | 14.8 | 5 | 0.8 | 3.375 | 1.375 | 40~50 | ISO 8737 |
| 6 mm | 6 | 3 | 19 | 6 | 1 | 3.85 | 1.625 | 45~60 | ISO 8737 |
| 8 mm | 8 | 4 | 23.25 | 8 | 1.25 | 5.35 | 2.125 | 55~75 | ISO 8737 |
| 10 mm | 10 | 4.5 | 25.5 | 10 | 1.5 | 6.8 | 2.625 | 65~100 | ISO 8737 |
| 12 mm | 12 | 5.3 | 28.75 | 12 | 1.75 | 8.3 | 3.125 | 85~120 | ISO 8737 |
| 16 mm | 16 | 6 | 37 | 16 | 2 | 11.75 | 4.15 | 100~160 | ISO 8737 |
| 20 mm | 20 | 6 | 37 | 16 | 2 | 11.75 | 4.15 | 120~190 | ISO 8737 |
| 25 mm | 25 | 7.5 | 42.5 | 20 | 2.5 | 14.75 | 5.15 | 140~250 | ISO 8737 |
| 30 mm | 30 | 9 | 49 | 24 | 3 | 17.75 | 6.15 | 160~280 | ISO 8737 |
| 40 mm | 40 | 10.5 | 61.5 | 30 | 3.5 | 22.75 | 7.25 | 190~320 | ISO 8737 |
| 50 mm | 50 | 12 | 74 | 36 | 4 | 27.75 | 9.2 | 220~400 | ISO 8737 |
Companion Standards
ISO 8737 controls the geometry of taper pins with external thread, unhardened. Surface finish is governed by separate finish standards such as ISO 4042 for electroplating, and corrosion testing by ISO 9227 (neutral salt spray). Mechanical performance is set by the documents specific to this part family — ISO 898-1 and ISO 898-2 apply to bolts, screws, studs and nuts, and not here.
When to Specify ISO 8737
Choose ISO 8737 for international engineering work and OEM supply where ISO standards are the contractual reference. It is the default modern specification for taper pins with external thread, unhardened.
Custom manufacturing · Made to drawing
Need a pin to this standard in a non-standard size?
Parts built to ISO 8737 are already in the catalog, so a special is usually a variation on existing tooling rather than a new design — which is what keeps the cost down. Made by cold heading or turning.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
