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Activity 001: Face Milling and Edge Finding Practice

Activity ID: U8M3-ACT-001 Duration: 45 minutes Objective: Set up a workpiece in the mill vise, perform edge finding on two perpendicular edges, and face mill the top surface flat.

Overview

Students set up an aluminum block in the mill vise, indicate the vise, practice edge finding to establish work coordinates, and face mill the top surface to produce a flat reference surface. This foundational exercise must be mastered before any precision milling work.

Materials & Equipment Needed

  • Vertical milling machine with indicated vise
  • 6061 aluminum block (2" × 3" × 1" thick)
  • 2" or 3" face mill with carbide inserts (or 3/4" end mill for smaller machines)
  • Edge finder (0.200" diameter)
  • R8 collets (for edge finder and face mill arbor)
  • Parallels
  • Brass mallet
  • Digital calipers
  • Safety glasses

Instructions & Procedure

Phase 1: Workpiece Setup (8 minutes)

  1. Verify the vise is indicated (check with an indicator if uncertain).
  2. Select parallels that elevate the workpiece approximately 1/4" above the vise jaws.
  3. Place parallels in the vise. Place the aluminum block on the parallels.
  4. Tighten the vise firmly. Tap the top of the workpiece with a brass mallet to seat it on the parallels.
  5. Verify both parallels are captive (cannot slide out by hand). If loose, loosen, reposition, and retighten.

Phase 2: Edge Finding (15 minutes)

  1. Install the edge finder in an R8 collet. Tighten the drawbar.
  2. Set spindle speed to 1000 RPM. Start the spindle.
  3. Find the X-axis reference (right edge of workpiece):
  4. Move the table in X until the edge finder is near the right edge of the workpiece.
  5. Slowly advance Y until the bottom half of the edge finder wobbles, aligns, then kicks.
  6. At the kick point, the spindle center is 0.100" from the edge.
  7. Zero the X-axis dial collar or DRO.
  8. Move the table 0.100" toward the workpiece. Re-zero. This is X=0 (right edge).
  9. Find the Y-axis reference (front edge of workpiece):
  10. Move the table to position the edge finder near the front edge.
  11. Repeat the process for the Y-axis. Zero at the front edge.
  12. Record both zero positions. These are your work coordinates.
  13. Stop the spindle. Remove the edge finder.

Phase 3: Face Milling (15 minutes)

  1. Install the face mill (or 3/4" end mill) in the appropriate toolholder. Tighten the drawbar firmly.
  2. Calculate RPM: Aluminum with carbide face mill, 2" diameter cutter → RPM = (1000 × 3.82) / 2 = 1910. Set to nearest available speed.
  3. Position the cutter over one edge of the workpiece. The cutter should overhang the workpiece width by approximately 30%.
  4. Lower the quill until the cutter barely touches the workpiece surface (listen for contact). Zero the Z-axis.
  5. Raise the cutter. Move to the starting position (cutter clear of one end of the workpiece).
  6. Lower Z by 0.020" (roughing pass). Lock the Z-axis and Y-axis.
  7. Feed the X-axis by hand or power feed across the full length of the workpiece.
  8. Retract in X. Step over in Y by 50-70% of the cutter diameter. Make another pass. Continue until the entire surface is machined.
  9. Finishing pass: Set Z to 0.005" below the roughed surface. Make a single pass across the entire width for a uniform flat surface.

Phase 4: Measurement and Evaluation (7 minutes)

  1. Remove the workpiece. Clean all chips.
  2. Measure the workpiece thickness at four corners and the center with calipers. All readings should be within 0.002".
  3. Visually inspect the surface: it should be uniformly smooth with consistent cutter marks.
  4. Deburr all edges with a deburring tool.

Discussion Points

  • What was the most challenging part of edge finding?
  • How do you know the parallels are properly seated?
  • What would happen if the vise was not indicated correctly?
  • How did the surface finish change between roughing and finishing passes?

Expected Outcomes

  • Accurate edge finding with repeatable results
  • Flat, uniform face-milled surface (within 0.002" flatness)
  • Proper vise setup with seated parallels
  • Correct RPM and feed rate for the operation

Assessment Rubric

Criteria Excellent (4) Proficient (3) Developing (2) Beginning (1)
Edge Finding Consistent kick detection, accurate zero Required 2 attempts, accurate Inconsistent kick detection Cannot perform edge finding
Vise Setup Parallels seated, workpiece secure, square Minor parallel seating issue Required guidance on setup Cannot set up workpiece properly
Face Milling Uniform surface, correct parameters Minor ridges, acceptable finish Uneven surface, parameter errors Cannot produce flat surface
Measurements All 5 readings within 0.002" 4/5 within 0.002" 3/5 within 0.002" Significant variation

Safety Considerations

  • Verify drawbar is tight before starting the spindle
  • Lock unused axes during cutting
  • Never reach under the face mill while it is spinning
  • Clear all chips before measuring—chips can give false readings
  • Face mill inserts can shatter on impact—ensure workpiece is secure
  • Safety glasses mandatory; face shield recommended for face milling

Last Updated: 2026-03-19