Spring (Roll) Pin

How roll pins work

A spring pin, also called a roll pin or tension pin, is a headless tube of spring steel with a slot along its length. Its body is slightly bigger than the hole it goes into, so it compresses as you drive it in and springs back against the wall of the hole. That spring force holds it in place, so it needs no nut, head or clip.

Roll pins secure two or more parts together. The parts can be fixed, or swivel on the pin once it is fitted, which is why they are used to hold gears, collars and handles on shafts, and as hinge and pivot pins.

Spring pin or solid pin?

• •Fits a standard size hole: no reaming, milling or tight-tolerance drilling.
• •Self-locking: the spring action keeps it in the hole.
• •Light: 30 to 40% lighter than a solid pin of the same size.
• •Strong: a spring pin can replace a solid cold-rolled or taper pin of the same diameter.
• •Reusable: tap it out with a pin punch and it returns to its original diameter, ready to use again.
• •Need exact location instead? Hardened dowel pins are made for accurate location of parts.

Roll pin sizes: matching the hole

A roll pin is sized by the hole it fits: a 4mm pin goes in a 4mm hole, a 1/4 inch pin in a 1/4 inch hole. Choose a length that passes through every part the pin has to hold, without standing proud where it could catch.

Measure the hole, or measure an old pin (it reads slightly over its size, because spring pins are made oversize), then match it to the table. If the machine is imperial, use the imperial pins rather than the nearest metric size. Spring pins are sold in packs of 100 to 1,000, depending on the size and length.

Black oxide or zinc plated?

• •Black oxide: our metric pins are S-LOK spring pins in black oxide spring steel, made to ISO 8752, with chamfered ends to help them start in the hole. As a general rule, black oxide gives little corrosion resistance on its own, so these pins suit dry or oiled parts.
• •Zinc plated: our imperial pins are zinc plated spring steel. Zinc plating is a thin (about 5 micron) coating recommended for indoor and non-corrosive conditions.
• •Neither finish is stainless, and we do not carry stainless spring pins in this range.

How to fit and remove a roll pin

1. Line up the holes in all the parts and drill through at the pin size if the hole is new.
2. Support the part on a solid surface so it does not bend as you drive the pin.
3. Start the pin by hand, either end first (both ends are chamfered), then tap it in with a hammer and a pin punch until it sits where you want it.
4. To remove it, support the part and drive the pin out from the other side with a pin punch or drift the same size as the pin or slightly smaller.
5. Check the pin: a spring pin returns to its original diameter once it is out and can be reused if it is undamaged.

Roll pins in Adelaide

Allmat supplies roll pins, split pins, dowel pins and machinery fasteners to mechanics, fitters, farmers and trade across Adelaide and South Australia. Add them to a quote with the rest of your list, and we will price the lot.

Questions