Selecting the right size rivet to use is done by determining the size of the specific rivet being replaced. The size of a rivet is generally determined by the part number, assigned for a particular rivet. If you do not have the part number available, the size will need to be calculated manually. You are able to do this through the use of simple arithmetic or converting the size of a measurement.
Write the part number for the rivet on a piece of paper.
Find the fourth character used in the part number. This character indicates the diameter of the rivet. If the number is a 4, the rivet has a diameter of 4/32, or 1/8 of an inch.
Find the fifth character used in the part number. This character indicates the grip range of the rivet. If the number is a 2, the grip range will be 2/16, or 1/8 of an inch.
Measure the diameter of the rivet with the caliper. Place the caliper over the rivet and read the gauge.
Measure from the underside of the rivet head to the tip of the rivet, with a ruler or tape measure. This will give you the length of the rivet. Make a note of the measurement on a piece of paper.
Subtract 1/8 of an inch from the length to calculate the grip range.
The diameter is calculated in 1/32 of an inch increments The grip range is calculated in 1/16 of an inch increments. The grip range of a rivet is typically 1/8 of an inch shorter than the length of the rivet.