M1109 Combo Lathe/Mill
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.
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.
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 | |
Wood |
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.
OPERATIONS