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M1109 Combo Lathe/Mill
OPERATIONS
Setting RPM
When using the milling machine, determine the RPM
needed to cut your workpiece, and adjust the gear
change levers to achieve the closest RPM
.
NOTICE
Never shift gears while lathe or mill is running; other-
wise, the gear teeth will be chipped or broken.
To determine and set the mill to the needed RPM, do
these steps:
1. Select the cutting speed required for the material of
your workpiece using the table in
Figure 37.
2. Measure the diameter of your cutting tool in inches.
3. Use the following formula to determine the needed
RPM for your operation:
(Cutting Speed x 4) / Tool Diameter = RPM
Note: You will only be able to get an approximate
RPM value with the variable speed knob.
4. Move the mill gearbox levers to the nearest milling
speed RPM.
Cutting Speeds for High Speed Steel (HSS)
cutting tools:
Workpiece Material Cutting Speed (sfm)
Aluminum & alloys 300
Brass & Bronze 150
Copper 100
Cast Iron, soft 80
Cast Iron, hard 50
Mild Steel 90
Cast Steel 80
Alloy Steel, hard 40
Tool Steel 50
Stainless Steel 60
Titanium 50
Plastics 300-800
Wood 300-500
Figure 37. High speed steel cutting chart.
Note:
Double the cutting speed for carbide
cutting tools. These values are a guideline
only. Refer to the MACHINERY'S HANDBOOK
for more detailed information.
NOTICE
Failure to follow RPM and Feed Rate
Guidelines will put undue strain on
moving parts, shorten tool life, poor
workpiece results and may threaten
operator safety from ejected parts or
broken tools.