I often need a reference to the exact center of a router bit on my router table. I usually had to resort to measuring, which was not always accurate. To solve the problem for good, I decided to mark “crosshairs” onto the table to indicate the precise center of any bit.
I tightened a V-groove bit into my router collet, so that the point of the bit would indicate the center of the router shaft. Then, using a 90° triangle aligned with the table edges, I marked lines directly over the point of the bit with a fine-tip permanent marker. Now the center of any bit is a certainty!
– Bill Wells