ISO 8748 Spiral Dowel Pins, Heavy Duty
ISO 8748 heavy-duty spiral (coiled) spring dowel pins d1 1,5 to 20 — the rolled, compressible shear pin with double-duty shear strength rows a/b per diameter, plus the full trade-length matrix (l 4 – 200).
Last updated: 2026-11
Specifications
ISO 8748 is the heavy-duty member of the coiled-pin family: a spring-steel strip rolled into a spiral tube that compresses when driven, springing outward to grip a standard-drilled hole along its whole length. No reaming, no press tonnage — a mallet drives it, and the radial spring holds it through vibration that would loosen a smooth dowel. "Heavy duty" is quantified in the collected table: the d1 ladder runs 1,5 to 20 with the before-mounting diameters (max./min. — the tube as rolled: 1,71/1,61 at d1 1,5 up to 21/20,4 at d1 20, comfortably above the hole so the walls stay loaded), and two minimum double-shear rows per diameter labelled a and b by the source (a: 1,9 kN at 1,5 → 340 kN at 20; b: 1,45 → 91 kN with the source's "-" cells at d1 14/16/20 carried verbatim) — the design numbers for shear-loaded joints, where coiled pins are deliberately chosen because they bend rather than snap. Chamfer a and material strip thickness s (0,17 → 2,2) complete the attribute rows. The trade-length matrix runs l 4 to 200 with the source's "+" availability marks per diameter — again the availability, not the geometry, constrains substitution. Holes: standard drill tolerance, unlike the reamed bore a solid dowel needs. Material, hardness and finish are not tabulated — per RFQ (spring-pin steel grades vary; confirm at quotation).
| Standard | ISO 8748 — spiral dowel pins, heavy duty (coiled spring pin) |
|---|---|
| Size range | d1 nominal: 1,5 – 20, fifteen diameters in the collected rows |
| Before-mounting diameter | max./min. per size: 1,71/1,61 (d1 1,5) → 21/20,4 (d1 20) — oversized as rolled |
| Shear strength | Minimum double shear per source rows a/b: a 1,9 → 340 kN; b 1,45 → 91 kN ("-" cells at d1 14/16/20 verbatim) |
| Section | a (chamfer): 0,5 → 4,5; s (strip thickness): 0,17 → 2,2 per diameter |
| Trade lengths | l 4 – 200 availability matrix, "+" marks the source's offered pairs |
| Material / hardness | Not tabulated by the collected specification — per RFQ |
| Attribute | Limit | 1,5 | 2 | 2,5 | 3 | 3,5 | 4 | 5 | 6 | 8 | 10 | 12 | 14 | 16 | 20 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| d1 | nom. | 1,5 | 2 | 2,5 | 3 | 3,5 | 4 | 5 | 6 | 8 | 10 | 12 | 14 | 16 | 20 |
| d1 | before mounting max. | 1,71 | 2,21 | 2,73 | 3,25 | 3,79 | 4,3 | 5,35 | 6,4 | 8,55 | 10,65 | 12,75 | 14,85 | 16,9 | 21 |
| d1 | min. | 1,61 | 2,11 | 2,62 | 3,12 | 3,64 | 4,15 | 5,15 | 6,18 | 8,25 | 10,3 | 12,35 | 14,4 | 16,4 | 20,4 |
| d2 | before mounting max. | 1,4 | 1,9 | 2,4 | 2,9 | 3,4 | 3,9 | 4,85 | 5,85 | 7,8 | 9,75 | 11,7 | 13,6 | 15,6 | 19,6 |
| a | = | 0,5 | 0,7 | 0,7 | 0,9 | 1 | 1,1 | 1,3 | 1,5 | 2 | 2,5 | 3 | 3,5 | 4 | 4,5 |
| s | 0,17 | 0,22 | 0,28 | 0,33 | 0,39 | 0,45 | 0,56 | 0,67 | 0,9 | 1,1 | 1,3 | 1,6 | 1,8 | 2,2 | |
| Minimum shear strength, double, kN | a | 1,9 | 3,5 | 5,5 | 7,6 | 10 | 13,5 | 20 | 30 | 53 | 84 | 120 | 165 | 210 | 340 |
| Minimum shear strength, double, kN | b | 1,45 | 2,5 | 3,8 | 5,7 | 7,6 | 10 | 15,5 | 23 | 41 | 64 | 91 | - | - | - |
| nom. | min. | max. | 1,5 | 2 | 2,5 | 3 | 3,5 | 4 | 5 | 6 | 8 | 10 | 12 | 14 | 16 | 20 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 4 | 3,75 | 4,25 | + | + | ||||||||||||
| 5 | 4,75 | 5,25 | + | + | + | |||||||||||
| 6 | 5,75 | 6,25 | + | + | + | + | + | |||||||||
| 8 | 7,75 | 8,25 | + | + | + | + | + | + | ||||||||
| 10 | 9,75 | 10,25 | + | + | + | + | + | + | + | |||||||
| 12 | 11,5 | 12,5 | + | + | + | + | + | + | + | + | ||||||
| 14 | 13,5 | 14,5 | + | + | + | + | + | + | + | + | ||||||
| 16 | 15,5 | 16,5 | + | + | + | + | + | + | + | + | + | |||||
| 18 | 17,5 | 18,5 | + | + | + | + | + | + | + | + | + | |||||
| 20 | 19,5 | 20,5 | + | + | + | + | + | + | + | + | + | + | ||||
| 22 | 21,5 | 22,5 | + | + | + | + | + | + | + | + | + | + | + | |||
| 24 | 23,5 | 24,5 | + | + | + | + | + | + | + | + | + | + | + | |||
| 26 | 25,5 | 26,5 | + | + | + | + | + | + | + | + | + | + | + | + | ||
| 28 | 27,5 | 28,5 | + | + | + | + | + | + | + | + | + | + | + | |||
| 30 | 29,5 | 30,5 | + | + | + | + | + | + | + | + | + | + | + | |||
| 32 | 31,5 | 32,5 | + | + | + | + | + | + | + | + | + | + | + | |||
| 35 | 34,5 | 35,5 | + | + | + | + | + | + | + | + | + | + | + | + | ||
| 40 | 39,5 | 40,5 | + | + | + | + | + | + | + | + | + | + | + | + | ||
| 45 | 44,5 | 45,5 | + | + | + | + | + | + | + | + | + | + | + | + | ||
| 50 | 49,5 | 50,5 | + | + | + | + | + | + | + | + | + | + | + | |||
| 55 | 54,25 | 55,75 | + | + | + | + | + | + | + | + | + | |||||
| 60 | 59,25 | 60,75 | + | + | + | + | + | + | + | + | + | |||||
| 65 | 64,25 | 65,75 | + | + | + | + | + | + | + | |||||||
| 70 | 69,25 | 70,75 | + | + | + | + | + | + | + | |||||||
| 75 | 74,25 | 75,75 | + | + | + | + | + | + | + | |||||||
| 80 | 79,25 | 80,75 | + | + | + | + | + | + | ||||||||
| 85 | 84,25 | 85,75 | + | + | + | + | + | + | ||||||||
| 90 | 89,25 | 90,75 | + | + | + | + | + | + | ||||||||
| 95 | 94,25 | 95,75 | + | + | + | + | + | + | ||||||||
| 100 | 99,25 | 100,75 | + | + | + | + | + | + | ||||||||
| 120 | 119,25 | 120,75 | + | + | + | + | + | + | ||||||||
| 140 | 139,25 | 140,75 | + | + | + | + | ||||||||||
| 160 | 159,25 | 160,75 | + | + | + | + | ||||||||||
| 180 | 179,25 | 180,75 | + | + | + | |||||||||||
| 200 | 199,25 | 200,75 | + | + | + |
Materials
- Material and hardness specified per RFQ — coiled pins are spring-steel (the resilience is the retention mechanism); state the joint duty (shear load, dynamic vs static), host material and any corrosion exposure at quotation
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (ISO 8748 Spiral Dowel Pins, Heavy Duty) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantities and lead times for this family are confirmed at quotation — send your sizes, grades and quantities on the RFQ and the quote will carry a firm schedule. Sample availability is confirmed with the quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
What do the two shear rows (a and b) in the collected table mean for a shear-loaded design?
The source prints two minimum double-shear ladders per diameter and labels them a and b — carried verbatim here with the "-" cells where the b row stops (d1 14/16/20). The a row is the heavy-duty ladder the ISO 8748 designation stands on (340 kN at d1 20); the b row tracks the light-duty ISO 8749 ladder (91 kN at d1 12, absent above) — the pairing is how the source's page juxtaposes the two duty grades. For a heavy-duty joint, design against row a: it is the number the ISO 8748 label certifies, e.g. 20 kN at d1 5 or 84 kN at d1 10. The coiled pin's design virtue is visible in those rows' purpose: in an overload the pin bends and keeps the joint aligned instead of fracturing like a solid dowel — you design the pin as the replaceable fuse. Two practical notes from the same table: the before-mounting diameters run above nominal (e.g. d1 8 pins are rolled at max. 8,55) so the hole is a standard drill size, not reamed; and lengths beyond the "+" matrix are RFQ lines. Material and hardness stay per RFQ.
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support