Lathe Trick – Tool Centering

Here is a neat trick I learned many years ago from an old tool maker.

Place a 6 inch ruler vertically between your tool point and something round mounted on the center line of your lathe. In this example, I used a dowel pin chucked in the tail stock.

You can see the ruler is leaning back. The tool needs to be lowered. When the ruler is perpendicular to the lathe bed, the tool will be on dead center (tangent to a circle). If the ruler was leaning forward, you would move the tool higher.

I am centering a boring bar in the above photo. You can use your work piece if it is a cylinder.