MACHINING Copyright Goodheart-Willcox Co., Inc. Chapter 26 Milling Machines 471 Often a slot has to be cut into a round workpiece. Use an electronic edge finder to position the center of the cutter at the center of a round piece of stock to mill a slot. Follow these guidelines: Milling a Slot or Keyway on a Vertical Milling Machine 1. Install the electronic edge finder into the adapter or chuck on the vertical milling machine spindle, Figure 26-75A. 2. Slowly feed the tip (stylus) of the edge finder against the outside diameter of the round part without the spindle rotating, Figure 26-75B. 3. When the stylus touches the part, the LED in the edge finder lights up, Figure 26-75C. Stop feeding the worktable immediately when this occurs. The center of the spindle will be exactly one-half the stylus tip away from the edge of the work. 4. Set the micrometer dial on the longitudinal feed to 0, Figure 26-76. Move the edge finder vertically to clear the workpiece. 5. Move the worktable longitudinally to center the workpiece (longitudinal movement = radius of the workpiece plus the radius of the stylus tip). 6. Install the end mill and mill the slot, Figure 26-77. 26.8.6 Machining Internal Openings Internal openings are easily machined on a vertical mill. A two-flute end mill must be used if the cutter is used to make the initial opening. The end mill can be fed directly into the metal like a drill. Chuck on a vertical mill Electronic edge finder Red light A B C Electronic edge Goodheart-Willcox Publisher Figure 26-75. Using an electronic edge finder. A—Edge finder mounted in the chuck of a vertical milling machine. B—Moving the electronic edge finder toward the workpiece using the longitudinal feed handwheel. C—An LED lights when the edge finder touches the workpiece. Goodheart-Willcox Publisher Figure 26-76. Set the micrometer dial on the longitudinal feed to 0. Goodheart-Willcox Publisher Figure 26-77. The end mill is centered above the round workpiece and is ready to mill a slot.