How to measure cotter pin

Split pin, otherwise known as cotter pin in the United States is a wedge or pin that passes through a hole in order to hold the parts tightly together. Some of the applications of cotter pin include, fixing ac rank to its crankshaft as in the case of piston rod, bicycle, or in a steam engine. An important point to note here is the wedge’s angle which determines position of the components held intact, and hence the pedal arms of a bicycle should be only held at 180 degrees to each other in case of equal angles of the cotter pin’s wedge on both pins. It is a very tricky job since, the cotter pin is available at 1/32’s of an inch diameter, and sometimes, it is even difficult to measure the length of the cotter pin. A calliper can be used to measure the length of the cotter pin if one is not sure of the correct diameter. The length of the cotter pin must be calculated from the base of the hole to the end of the shortest prong. Here’s a guide that tells how to measure a cotter pin.

cotter pinThe length of any cotter pin is not standardised and it can be measured based on the kind of points, a cotter pin has. The measurement starts at a point where larger edge of the pin joins the hole into which it is inserted. The measurement ends for pins with

  • Bevel or miter point ends, at the finish of the utmost end of both the prongs
  • Hammerlock edges, at the last point of the lengthier prong
  • Other kinds, at the last point of the shorter prong

Step 1:

Measure the diameter of the hole to which the cotter pin would be fixed

Step 2:

Once the hole’s diameter is calculated, measure the diameter of the two prongs of the cotter pin, which are held closely together

Step 3:

Once all the measurements of different parts of the cotter pin are done, choose a cotter pin of diameter, which is similar that of the hole. Any cotter pin, which is more than 5/16 of an inch in diameter, must fit into a hole of similar diameter dimensions.

Step 4:

After identifying cotter pins that have similar diameter to that of the hole, measure the length of the hole, which has to be fastened.

Step 5:

Assess the length of the cotter pin beginning from base of the blunt end of the pin till the shorter prong.

Step 6:

In this final step, choose a cotter pin which has an appropriate diameter and that fits the length of the hole, which has to be fastened. The rounded end of the cotter pin must be fixed in a particular end of the hole and pull out to the extent the short end comes out on the other end of the hole.