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Light-Duty Coiled Spring Pin Dimensions (ISO 8751, 1.5 to 8 mm)
Guide · Updated October 28, 2026
ISO 8751 covers light-duty coiled spring pins, 1.5 to 8 mm. Values agree across the ISO 8751:2007 preview (iTeh), fasten.it DIN EN ISO 8751 and the pinfastener DIN EN ISO 8751 sheet. Check your supplier for critical work.
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Step by step
- Pick the pin size: Nominal d1, 1.5 to 8 mm, equals the hole size. Drill to H12.
- Check the strip: s is the coiled strip thickness. Light duty is about half the heavy-duty ISO 8748 wall.
- Check the load: Use the steel or martensitic column, or the austenitic column for A pins.
- Order it: Designate as Spring pin ISO 8751 - 6 x 30 - St.
ISO 8751 light-duty coiled spring pin dimensions (mm)
Columns: nominal d1, d1 before fitting (min–max), d2 max, chamfer a ≈, strip s, minimum double shear kN (steel and martensitic), same (austenitic).
- Nominal | d1 before fitting | d2 max | a | s | shear kN steel | shear kN austenitic
- 1.5 | 1.62–1.75 | 1.4 | 0.5 | 0.08 | 0.8 | 0.65
- 2 | 2.13–2.28 | 1.9 | 0.7 | 0.11 | 1.5 | 1.1
- 2.5 | 2.65–2.82 | 2.4 | 0.7 | 0.14 | 2.3 | 1.8
- 3 | 3.15–3.35 | 2.9 | 0.9 | 0.17 | 3.3 | 2.5
- 3.5 | 3.67–3.87 | 3.4 | 1 | 0.19 | 4.5 | 3.4
- 4 | 4.20–4.45 | 3.9 | 1.1 | 0.22 | 5.7 | 4.4
- 5 | 5.2–5.5 | 4.85 | 1.3 | 0.28 | 9 | 7
- 6 | 6.25–6.55 | 5.85 | 1.5 | 0.33 | 13 | 10
- 8 | 8.30–8.65 | 7.8 | 2 | 0.45 | 23 | 18
Worked example: 3 mm light-duty coiled pin
A 3 x 16 ISO 8751 pin goes into a 3 mm H12 hole in a plastic or die-cast part. Before fitting it measures 3.15 to 3.35 mm, and the 0.17 mm strip coils down to fit. In steel it holds at least 3.3 kN in double shear.
Common problems
- Host cracks: drill exactly H12 and support the part.
- Pin loose: hole oversize; do not ream larger.
- Pin shears: move to ISO 8750 or 8748.
FAQ
What is ISO 8751?
The light-duty coiled (spiral) spring pin, 1.5 to 8 mm. Use it in soft, brittle or thin parts where a heavy pin would crack the host. ISO 8748 is heavy duty and ISO 8750 standard duty.
How is it different from ISO 8748?
Same hole sizes, but a thinner strip. For example 6 mm is 0.33 mm here against much thicker on ISO 8748, and steel shear is 13 kN.
Why is 2 mm austenitic shear 1.1?
The ISO preview and fasten.it give 1.1 kN; one maker PDF shows 1. We used 1.1.
What was skipped?
Length ranges per size. Diameter before fitting comes from the ISO preview and pinfastener; fasten.it does not list it.
Related guides and calculators
- Standard-duty coiled spring pins (ISO 8750)
- Coiled spring pin chart (ISO 8748 heavy duty)
- Light-duty slotted spring pins (ISO 13337)
- Slotted spring pin chart (ISO 8752)
- Parallel pins (ISO 2338 / DIN 7)
- All free machinist calculators
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