Machine components

How to Measure Brackets, Spacers, Springs and Fasteners

A dimensioned sketch and a photo of the mounting position help identify hardware with no readable part number. Mark the reference edge or face on the sketch and use the same reference for related dimensions.

Where to measure

Reference drawings. Verify dimensions on your part or the manufacturer’s drawing.

Bracket hole pattern

Use the same reference edge for the first hole location. Measure center to center between holes, then record hole diameter and plate thickness separately.

Spacer diameters and length

Measure the bore and outside diameter across their centers. Measure length between the two flat end faces.

Compression spring free length and diameter

Use the spring unloaded. Measure between the ends and across the widest outside edges. Measure wire diameter across one strand separately.

Screw length and thread size

For a socket-head screw, measure from under the head to the tip. For a countersunk screw, include the head. Measure thread diameter crest to crest.

Machined bracket, spacer, compression spring and screws

Brackets and spacers

For a bracket, capture overall length, width and thickness, then measure hole diameter and hole centers from a reference edge. Note slots, bends, tapped holes and counterbores. For a spacer, record inside and outside diameter and overall length. Measure flange diameter and thickness separately on a flanged spacer.

Compression springs

Use an unloaded spare or the original drawing to record free length, outside diameter and wire diameter. Note the end style and coil count. A spring that has taken a permanent set can measure shorter than the original specification. Provide the material and spring rate or specified load at a known length when available.

Fasteners and finishes

Record nominal thread diameter and pitch, length, head and drive style, and any grade markings. Label your length reference. Most standard screws are measured from under the head, while countersunk screws generally use overall length. Include material and finish when specified on the drawing.

Manufacturer reference: MISUMI compression spring catalog and dimension drawings