Pins
What are Pins?
Pins are simple mechanical fasteners used to align, locate, or retain components. This category focuses on two workhorse types: precision dowel pins for alignment and shear, and cotter pins for low-profile retention through a drilled hole.
How to choose pins
- Function: Use dowel pins for accurate alignment or to share shear load between parts. Use cotter pins to lock a clevis pin or castellated nut after assembly.
- Diameter & hole fit: For dowel pins, pick a nominal diameter, then choose a press fit for permanent alignment or a slip fit where removal is needed. For cotter pins, match the pin to the drilled hole the hardware provides.
- Material & environment: Stainless steel for corrosion resistance, zinc-plated or plain steel for general indoor use, brass for non-magnetic or cosmetic needs.
- Length & grip: Dowel length should fully span the joint with engagement in both parts. Cotter length should allow both tines to bend back over the part after insertion.
- Strength & service: Choose hardened steel dowels for high shear or repeated locating. Use stainless cotter pins where moisture is present.
Common sizes, materials & finishes
- Dowel pins: Typical diameters from 1/16 in to 1/2 in, common lengths from 1/4 in to 3 in. Materials include 18-8 and 316 stainless steel, alloy or carbon steel, with plain or passivated finishes.
- Cotter pins: Typical diameters from 1/32 in to 1/4 in, lengths from 1/2 in to 4 in. Materials include low-carbon steel, 18-8 or 316 stainless, and brass, with plain or zinc-plated finishes.
Typical applications & industries
- Machinery and fixtures, jigs, and tooling alignment
- Automotive, ag, and equipment linkages using clevis pins
- Furniture, cabinetry, and assembly lines needing repeatable location
- Marine and outdoor assemblies using stainless components
Installation & best practices
Dowel pins
- Deburr and clean the mating holes. Verify size tolerance for press or slip as required.
- Support the part and press the pin squarely using an arbor press. Avoid hammering to prevent mushrooming.
- For slip-fit locating, install dowels in the base part and use slip holes in the mating part for easy assembly.
Cotter pins
- Insert the tines through the drilled hole of the shaft or clevis pin until the head seats.
- Spread the tines in opposite directions with pliers to lock the hardware. Trim only if necessary to avoid snagging.
Troubleshooting & pro tips
- Pin walks out: Hole oversize or misaligned. Ream to a known size and use a press-fit dowel, or replace worn components.
- Galling during installation: Lubricate lightly, confirm interference is within spec, and press instead of hammering.
- Corrosion at joints: Choose 316 stainless in marine or chemical exposure, or isolate dissimilar metals.
- Cotter pin breaks at bend: Select a larger diameter or stainless material, and bend gradually with pliers rather than sharply at the same spot.
Why buy Pins from AlbanyCountyFasteners.com
- Wide selection of stainless and steel dowel pins and cotter pins with popular diameters and lengths
- Corrosion-resistant options for outdoor and marine environments
- Bulk quantity price breaks and fast shipping from our U.S. warehouse
- Technical product pages and responsive support to help you choose correctly
Pins FAQ
Choose the nominal diameter that matches your hole plan, then pick a length that fully engages both parts without bottoming.
Use a slightly undersize reamed hole for a press fit in one part and a slightly oversize reamed hole for a slip fit in the mating part. Follow your print or standard.
Most steel dowel pins are through-hardened for wear and shear strength. Stainless versions prioritize corrosion resistance over high hardness.
Match the cotter pin diameter to the hole in the shaft or clevis pin, and choose a length that lets both tines bend back securely.
No. Cotter pins are single-use retainers and should be replaced after removal.
Use stainless steel. 18-8 works for general outdoor exposure, and 316 is preferred for marine or harsh environments.
Use a press-fit dowel in one part and a slip-fit hole in the other, or use one dowel for location and a bolt for draw-in to accommodate small stack-ups.
Deburr holes, support the work, and press the pin squarely with an arbor press. Avoid hammering to prevent mushrooming.