Final answer:
Before turning on a milling machine, three things to check are the secure workpiece, tooling, and machine settings.
Step-by-step explanation:
Before turning on a milling machine, there are three important things to check:
- Secure workpiece: Make sure the workpiece is clamped securely to prevent movement during milling.
- Tooling: Verify that the correct cutting tool is installed and properly tightened.
- Machine settings: Check and adjust the spindle speed, feed rate, and depth of cut to ensure they are appropriate for the material and operation.