Ron Pope Motorsports                California Custom Roadsters               

Lathe Boring Calculator

Mr. Fixit

While fabricating the anvil wheels for my new home built E-Wheel, I quickly realized that in order to get accurate and repetative press fit results for the bearings on my manual lathe, I needed a formula in order to expedite the process and be more successful.

For those of you that are amatuer machinists or hobbiests and own a lathe, from time to time you will need to use your lathe to bore holes larger than drill/ream sizes. When using a boring bar, regardless of type, there will always be bar deflection, and therefore inaccuracies in the hole size compared to what you expected based upon your setting. I have developed a very straight forward spreadsheet which will take all of the guess work out of your boring operations, even if your lathe is somewhat old and worn.

The boring concept remains the same, whereas you make your rough cuts in order to get close to the desired finish hole dimension, while leaving enough material for 3 finish cuts of almost equal depth. By doing so, the boring bar will react in the same manner with each pass, and therefore predictable results are attainable.

The intent is to determine (based upon your own experience, your lathe, and the material being machined) how much material can be removed with each rough cut and how much can be removed with each finish cut. This information, along with the desired finished hole dimension and the starting dimension after drilling are entered into the worksheet. As long as you can accurately measure, you will be pleased with the repetitive results.

The instructions for the use of this spreadsheet are written within the worksheet itself. Enjoy.

Someone please let me know if and how I can attach the spresdsheet and I will be happy to do so.:D


     Ron Pope Motorsports                Advertise with Us!