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Slotted Spring Pin Size Chart (ISO 8752 Heavy Duty)

Guide · Updated October 28, 2026

A slotted spring pin, usually called a roll pin, is a hardened steel strip rolled into a tube with a lengthwise slot. Its free diameter is a little larger than the hole, so it closes up as it is driven and holds by spring pressure against the bore. ISO 8752 (formerly DIN 1481) covers the heavy-duty version from 1 mm to 50 mm. The nominal size is the hole size, not the pin size. The table below gives the common 1 to 10 mm sizes. The figures come from the ISO 8752:2009 preview table and match Aspen Fasteners’ DIN 1481 / ISO 8752 spec sheet.

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Step by step

Pick the nominal size: Pick the nominal diameter from the load and the room you have. The nominal size is the diameter of the hole you drill.
Drill the hole to nominal: Drill or ream the hole to the nominal size. ISO 8752 sets a tolerance of H12 on the hole, so an ordinary jobber-drilled hole in good condition is usually fine.
Check the free diameter: Mike the pin before it goes in. It should read inside the before-fitting range in the chart, so it is always oversize to the hole.
Line up the parts: Line up the holes in both parts. A pilot punch or a slightly undersize drill blank held through the stack keeps them in line.
Drive with a roll pin punch: Start the chamfered end and drive the pin with a roll pin punch, the kind with a pilot nub. A flat punch can mushroom the end or split it open.
Orient the slot: In a shear joint, turn the slot away from the load direction, toward the neutral side, so the full wall carries the shear.

ISO 8752 heavy-duty dimensions (mm)

Columns are: nominal size (the hole), free diameter d1 before fitting (min–max), chamfer diameter d2 before fitting, wall thickness s, and minimum double shear load in kN. The double shear value is for steel and martensitic stainless pins.

Nominal (hole) | d1 before fitting | d2 | Wall s | Min double shear kN
1 | 1.2–1.3 | 0.8 | 0.2 | 0.70
1.5 | 1.7–1.8 | 1.1 | 0.3 | 1.58
2 | 2.3–2.4 | 1.5 | 0.4 | 2.82
2.5 | 2.8–2.9 | 1.8 | 0.5 | 4.38
3 | 3.3–3.5 | 2.1 | 0.6 | 6.32
3.5 | 3.8–4.0 | 2.3 | 0.75 | 9.06
4 | 4.4–4.6 | 2.8 | 0.8 | 11.24
4.5 | 4.9–5.1 | 2.9 | 1.0 | 15.36
5 | 5.4–5.6 | 3.4 | 1.0 | 17.54
6 | 6.4–6.7 | 4.0 | 1.2 | 26.04
8 | 8.5–8.8 | 5.5 | 1.5 | 42.76
10 | 10.5–10.8 | 6.5 | 2.0 | 70.16

ISO 8752 continues past 10 mm, through 12, 13, 14, 16, 18, 20, 21, 25, 28, 30, 32, 35, 38, 40, 45 and 50 mm. For those sizes, use the standard itself or your supplier’s sheet. Standard lengths in the 2009 edition run from 4 mm up to 200 mm. The short lengths have a tolerance of about ±0.25 mm, and the longer ones get a wider band.

Worked example: shear check on a 6 mm pin

A 6 mm heavy-duty roll pin through a collar and a shaft runs in double shear, because the pin crosses the shaft and is cut at two faces. The chart gives a minimum double shear load of 26.04 kN. If the torque on a 25 mm shaft is 150 N·m, the force at the pin is about 150 / 0.0125 = 12,000 N. That is split across two shear planes, so the pin sees 12 kN against a 26 kN rating, a safety factor of about 2.2. If the load reverses or comes in shocks, go up a size to 8 mm (42.76 kN). Or use two pins at 90°, which adds rating and spreads the load.

Single shear, where a pin just ties two flat plates together, is roughly half the double-shear figure. Aspen’s sheet lists 13 kN for a 6 mm pin in single shear.

Light duty, nesting and coiled pins

ISO 13337 covers light-duty slotted pins. They have a thinner wall for softer hosts and are sized so a light-duty pin nests inside a heavy-duty pin, slots opposite, which gives more shear in the same hole. Coiled spring pins (ISO 8748 heavy, ISO 8750 standard and ISO 8751 light duty) are spirals, not slotted tubes. They spread stress more evenly and stand up better to fatigue. ASME B18.8.2 covers inch spring pins. Do not mix inch and metric charts, because the hole sizes are different.

Common problems

Pin walks out: the hole is oversize, often from a worn drill or a hole reamed too big. Re-drill to the next size up, or use a heavy-duty pin.
Pin will not start: the hole is too small, or the parts are out of line. Check the hole with a pin gage before you hit it harder.
Soft host cracks: in aluminum or plastic, use light-duty or coiled pins and keep the hole well back from the edge.
Pin snapped in shear: check whether the slot faced the load, and check the double-shear math above.

FAQ

Is the roll pin size the pin or the hole?

It is the hole. A 5 mm roll pin goes in a 5 mm hole. Its free diameter is 5.4 to 5.6 mm before you drive it.

What hole tolerance does ISO 8752 call for?

H12 on the nominal diameter. That is a loose tolerance, which is why plain drilled holes usually work.

Can I reuse a roll pin?

It is not recommended. A pin that has been driven out often loses some of its spring, so put in a new one, especially in a shear joint.

What is the difference between ISO 8752 and DIN 1481?

DIN 1481 was the German heavy-duty roll pin standard. ISO 8752 replaced it with essentially the same sizes.

Pin and retaining-ring size charts

Picking a fastener to locate or retain a part? Compare the other pin and ring charts in this set:

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General shop information only — follow your drawing, tool maker's data and your quality system.