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Taper Pin with External Thread Dimensions (ISO 8737 / DIN 7977, 5 to 50 mm)
Guide · Updated October 28, 2026
ISO 8737 covers unhardened 1:50 taper pins with an external thread (it replaced DIN 7977), 5 to 50 mm. The values agree between the ISO 8737:1986 preview (iTeh) and the globalfastener.com ISO 8737 table. Engineering Hardware agrees on a, d2 and P and on the midpoints of b, d3 and z. Check your supplier for critical work.
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Step by step
- Pick the taper size: d1 (h10) is the small-end diameter at the taper, 5 to 50 mm; ream the hole with a 1:50 taper reamer.
- Read the thread: d2 x P, e.g. M10 x 1.5 for a 10 mm pin.
- Check thread length: b is the thread length, between b min and b max.
- Check the neck: d3 is the neck diameter and z the chamfer at the threaded end.
- Order it: Designate as Taper pin ISO 8737 - 10 x 80 - St.
ISO 8737 threaded taper pin dimensions (mm)
Columns: taper diameter d1 (h10), a max, thread length b max and min, thread d2, pitch P, neck d3 max and min, chamfer z max and min.
- d1 | a max | b max | b min | d2 | P | d3 max | d3 min | z max | z min
- 5 | 2.4 | 15.6 | 14 | M5 | 0.8 | 3.5 | 3.25 | 1.5 | 1.25
- 6 | 3 | 20 | 18 | M6 | 1 | 4 | 3.7 | 1.75 | 1.5
- 8 | 4 | 24.5 | 22 | M8 | 1.25 | 5.5 | 5.2 | 2.25 | 2
- 10 | 4.5 | 27 | 24 | M10 | 1.5 | 7 | 6.6 | 2.75 | 2.5
- 12 | 5.3 | 30.5 | 27 | M12 | 1.75 | 8.5 | 8.1 | 3.25 | 3
- 16 | 6 | 39 | 35 | M16 | 2 | 12 | 11.5 | 4.3 | 4
- 20 | 6 | 39 | 35 | M16 | 2 | 12 | 11.5 | 4.3 | 4
- 25 | 7.5 | 45 | 40 | M20 | 2.5 | 15 | 14.5 | 5.3 | 5
- 30 | 9 | 52 | 46 | M24 | 3 | 18 | 17.5 | 6.3 | 6
- 40 | 10.5 | 65 | 58 | M30 | 3.5 | 23 | 22.5 | 7.5 | 7
- 50 | 12 | 78 | 70 | M36 | 4 | 28 | 27.5 | 9.4 | 9
Worked example: 10 mm threaded taper pin
A 10 x 80 ISO 8737 pin has an M10 x 1.5 stem, 24 to 27 mm of thread, and a 6.6 to 7 mm neck. To remove it, thread a nut on the stem and tighten it against a spacer.
Common problems
- Pin will not seat: ream the hole with a 1:50 taper reamer to the right depth.
- Stem thread damaged: use a 6g nut and do not hammer the stem.
- Mixed with internal-thread pins: those are ISO 8736 (taper) or ISO 8733/8735 (parallel).
FAQ
What is ISO 8737?
Unhardened 1:50 taper pins with a threaded stem, 5 to 50 mm. A nut on the thread pulls the pin out of a through or blind hole. It replaced DIN 7977.
How is it different from ISO 2339?
ISO 2339 is a plain taper pin. ISO 8737 adds a threaded stem for removal.
Is this ISO 8733 or DIN 7978?
No. ISO 8733 is an unhardened parallel pin with an internal thread (same thread and depths as ISO 8735). DIN 7978 / ISO 8736 is a taper pin with an internal thread. Neither is externally threaded.
Why do 16 and 20 mm share a thread?
The standard gives M16 for both sizes, with the same b, d3 and z.
What was skipped?
Length ranges per size, because the sources disagree. fasteners.eu lists a different table and was not used. The thread is 6g.
Related guides and calculators
- Internal-thread taper pins (ISO 8736 / DIN 7978)
- Metric taper pin chart (ISO 2339)
- Taper pin size chart (inch)
- Threaded dowel pins (ISO 8735 / DIN 7979)
- Metric dowel pin chart (ISO 8734)
- Parallel pins (ISO 2338 / DIN 7)
- All free machinist calculators
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