Smithy Midas 1220 XL - Manual (Page 41)

To use this formula, find the cutting speed you need on the chart and plug that number
into the CS portion of the formula. After calculating the rpm, use the nearest or
next-lower speed on the lathe and set the speed.
If you were to make a finish cut on a piece of aluminum 1” in diameter, for
example, you would see the desired sfm per Figure 8.3 is 300. Then
rpm = 300 sfm x 4 / 1
rpm = 1200 / 1
rpm = 1200 or next slower speed.
For high-carbon steel, also 1” in diameter,
rpm = 50 sfm x 4 / 1
rpm = 200 / 1
rpm = 200 or next slower speed.
With the four-turret toolpost, you can install all standard-shaped turning and facing tools
with 1” on smaller shanks. The centerline is approximately 5/8” above the bottom of the
turret. Smithy also offers quick-change tool sets that greatly speed up lathe operations.
Contact a Smithy technician for details.
8-4 Or Visit www.smithy.com
Metalcutting Theory