Using a coaxial indicator to find the center of a circle is simple and can be learned quickly. Part of what makes this tool so great is how straightforward it is to use. First, set up the coaxial indicator. You will need to select the probe that is best-suited to the centering job you are completing. Curved probes are good for outside centering, straight probes are best for inside centering, and short and pointy probes are ideal when centering a center point. After selecting the appropriate probe, insert it into the indicator and tighten it with a wrench. Second, get the coaxial indicator ready for the mill. You will need to insert and secure a collet into your mill. Then you can mount the coaxial indicator into the collet and tighten the draw bar to hold it in place. Third, set up the mill itself. After attaching the coaxial indicator, you will want to set up the actual mill, typically on a low speed. Set your RPM and attach the handle to the coaxial indicator. Fourth, set up the workpiece. Eye up the workpiece so that it is centered across the x-axis and y-axis. Make any necessary adjustments to the coaxial indicator to properly center the part. Fifth, center the coaxial indicator on the mill. You are ready to take a measurement. Once the probe on the coaxial indicator is spinning, ensure that it is hitting the proper surface of your part all the way around and simply read out the measurement on the dial.