Introduction: Milling Concepts

CONVENTIONAL CUTTING VS. CLIMB CUTTING

Conventional cutting is when the workpiece moves against the direction of the cutting bit.

  • All manual mill work should be done with conventional cuts.

Climb cutting is when the workpiece moves in the same direction as the bit.

  • This is not advised on the manual mill.
  • Climb cutting should be reserved for CNC milling.

CUTTING WIDTH AND DEPTH

An end mill can only remove a certain amount of material at once.

The maximum depth and width of cut is 1/2 of the end mill diameter.

  • For example, a 1/2" end mill can cut no more than 1/4" deep and 1/4" wide in a single pass.
  • A slotting cut is an exception to the width of cut rule.

USING THE POWER FEED

The power feed moves the table at a constant rate, which can help improve finish quality.

  1. Turn the speed dial to 0.
  2. Move the lever in the direction you want the table to move.
    • In the illustration, the table will be moving to the right.
  3. Adjust the feed rate by turning the speed dial.

Edge Finding

For accurate work, each axis needs to have a known zero point (origin). There are two ways to determine zero; create it or find it.


CREATING A ZERO

X or Y axis

  1. Take a light cutting pass to make the edge flat and square.
  2. Turn off the mill.
  3. On the DRO (see next lesson) zero the axis.
    • In this example, zero the X axis.
  4. Move the end mill 1/2 its diameter towards the center of the workpiece.
    • This will center the spindle over the edge of the material.
  5. Zero the axis on the DRO again.

Z axis

  1. Take a light cutting pass across the top of the part.
  2. Set the Z axis to zero.
    • The zero will need to be reset if the quill moves, or you change the end mill.

FINDING A ZERO

X or Y axis

  1. Install an edge finder.
  2. Push the bottom of the edge finder over 1/8".
  3. Start the mill and adjust to 800 RPM.
  4. Very slowly move the edge finder into the edge of the material until the bottom pops over to one side.
  5. Zero the axis on the DRO.
  6. Repeat step 4 to double check.
  7. Move the edge finder 1/2 its diameter towards the center of the workpiece
    • This will center the spindle over the edge of the material.
  8. Zero the axis on the DRO again.

Z axis

  1. Install the end mill.
  2. Lower the quill (or raise the table with the quill locked) until the end mill gently touches the table.
  3. Lock the quill.
  4. Set the Z axis to zero.
    • The zero will need to be reset if the quill moves, or you change the end mill.