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Welcome to the Technifast Talks Manufacturing Blog, where we'll be sharing our news, views and latest manufacturing articles.  Keep up to date with our latest fastener innovations and to discover how our fasteners and turned components are applied across a wide range of industries.



How To Measure A Cotter Pin

2nd Jan 2020

Split cotter pins are a type of mechanical fastener designed to couple two components together.  They’re formed from semi-circular wire bent to create a looped head, with two tines that can be spread to create a locking mechanism to keep the pin securely in place.

Cotter pins are designed to be easy to insert into pre-drilled components and due to their compatibility with clevis pins they are often used in construction, marine and agricultural industries.

The pins are very easy to install and remove and are meant for single use only, which means they offer a reliable fastening solution for light-duty applications where permanent fasteners might be an unacceptable choice.

Our cotter pins are supplied in a choice of mild steel, stainless steel or brass in wide a range of sizes. It is important to note that the nominal diameter of the pin is larger than the actual diameter. For example a pin with a nominal diameter of 5mm will have an actual diameter of 4.4 – 4.6mm. The nominal diameter is the same as the recommended hole size.

Here’s our step-by-step guide to measuring a cotter pin:

1.       Measure the diameter of the hole in which the pin will be inserted

2.       Measure the diameter of the two tines of the cotter pin when held closed.

3.       Select a cotter pin with a diameter which is very similar to the hole.

4.       Measure the length of the hole

5.       Choose a cotter pin with enough length to penetrate the hole and allow the prongs to be splayed to keep the pin secure. The nominal length of a cotter pin is the length of the shorter leg, not counting the head

Visit the cotter pin information page on our Technifast website for details of the sizes we can offer.



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