Finding center can be frustrating when you are in the shop and need a quick way to place a biscuit or dowel or mortise.
This simple math trick does the job for you.
Drill two holes in a piece of 3/8" thick stock that are 2" a part and exactly the size of your selected dowel material
The center hole should be the diameter of your favorite pencil stock.
All the holes must line up along a straight pencil line for this to work.
Drill a hole dead center between the previous dowels for the pencil.
If it's a bit loose set a screw through the side of your wood to hold it .
By placing a dowel on each side of your wood and running down the stock with the dowels touching the sides you will draw a line dead center on the work.
You may want to stack more layers up to hold the pencil so the sharp end doesn't protrude as much.