# How to locate the centre of a workpiece using a jenny caliper?

Before beginning trying to locate the centre of a workpiece using a jenny caliper it is important to make sure that you have everything you need. To follow our step-by-step guide you will need a ruler, a jenny caliper, an outside caliper and the workpiece that you wish to measure.

## Step 1 - Measure diameter of workpiece

Measure the diameter of the workpiece with the outside caliper. Transfer this measurement to the ruler, then half it to find the radius of the workpiece.

## Step 2 - Set jenny caliper to required distance

Set your jenny caliper to this distance.

## Step 3 - Position caliper on workpiece

Set the locating lug to the edge of the workpiece.

## Step 4 - Score arcs onto workpiece

Score four short, circular arcs onto the surface of the workpiece. These four arcs will form a rough square.

## Step 5 - Join corners of square

Join the corners of the ‘square’ together. The point at which the lines intersect will be the approximate centre of the workpiece.