Calculate lathe RPM, SFM, diameter, feed rate, or woodturning RPM range from surface speed, workpiece size, feed per revolution, and RPM.
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Lathe RPM Formula
The following equation is used to calculate the Lathe RPM.
- Where LRPM is the lathe rotations per minute
- SFM is the surface feet per minute
- D is the workpiece cutting diameter (in)
To calculate lathe RPM, divide surface feet per minute by the workpiece cutting diameter in inches, then multiply by 12/pi (approximately 3.82).
What is a Lathe RPM?
Definition:
A lathe RPM is defined as the rotation speed at which a lathe machine is turning. The appropriate lathe RPM depends on the workpiece cutting diameter, tool, material, operation, and machine limits.
How to Calculate Lathe RPM?
Example Problem:
The following example outlines the steps and information needed to calculate Lathe RPM.
First, determine the SFM of the lathe. In this example, the surface feet per minute is given as 4,000.
Next, determine the workpiece cutting diameter. In this example, the diameter is 10 inches.
Finally, calculate the Lathe RPM using the formula above:
LRPM = SFM/D * 3.82
LRPM = 4,000/10 * 3.82
LRPM = 1528 RPM
