Smithy GN1300 - Manual (Page 106)

In everyday lathe operations like thread cutting and knurling, always use a cutting oil or
other lubricant. On such work, especially if the cut is light and lathe speed low, dipping
a brush in oil occationally and holding it against the workpiece will provide sufficient
lubrication. For continuous, high-speed, heavy-duty production work, however, especially
on tough alloy steels, using a cutting oil or coolant will increase cutting efficiency. It's
essential if you're using a non-HSS cutting tool. When you use coolant, direct it against
the cutting point and cutter. Consider installing a coolant system if you don't have one.
To set up safe rpm rates, you should follow the list for cutting speeds and feeds for HSS
cutters. The formula is as follows:
rpm = CS x 4 / D”
where:
CS - cutting speed in surface feet per minute (sfm)
D” - diameter of the workpiece in inches.
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 is 300. Then
rpm = 300 sfm x 4 / 1
rpm = 1200 / 1
rpm = 1200 or next lower speed.
For high-carbon steel, also 1” in diameter,
rpm = 50 sfm x 40 / 1
rpm = 200 / 1
rpm = 200 or next slower speed.
The four-turret toolpost lets you mount up to four different tools at the same time. You
can install all standard-shaped turning and facing tools with 1/2” or 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.
Granite 1300 Series Operator’s Manual
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