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Activity 001: Bowl Exterior Turning and Tenon Creation

Activity ID: U7M4-ACT-001 Duration: 45 minutes Objective: Mount a bowl blank on a faceplate, turn the exterior profile, and create a properly sized tenon for scroll chuck mounting.

Overview

Students mount a pre-cut bowl blank on a faceplate, true the blank to round, shape the exterior bowl profile, and turn a tenon with the correct dovetail angle for their scroll chuck. This activity focuses on the first half of bowl turning—exterior work and chuck preparation.

Materials & Equipment Needed

  • Wood lathe with faceplate and scroll chuck
  • Pre-cut bowl blank (6" diameter x 3" thick, kiln-dried maple or cherry)
  • Bowl gouge (1/2"), parting tool, round-nose scraper
  • Faceplate with #10 x 1" hardened wood screws
  • Outside calipers, ruler
  • Chuck jaw size reference card
  • Safety glasses, face shield, dust mask, hearing protection
  • Sandpaper (150, 220, 320 grit)

Instructions & Procedure

Phase 1: Faceplate Mounting (8 minutes)

  1. Mark the center of the blank on the face that will become the bowl bottom.
  2. Position the faceplate centered on the blank. Mark screw holes with an awl.
  3. Drill pilot holes (7/64" bit for #10 screws).
  4. Drive all faceplate screws firmly. Verify the blank sits flat with no gaps.
  5. Thread the faceplate onto the spindle. Hand-tighten firmly.
  6. Bring up the tailstock with a live center into the face of the blank.
  7. Set the tool rest parallel to the blank edge, 1/4" away, at center height.
  8. Set speed to 800 RPM. Hand-rotate to check clearance.

Phase 2: Truing and Exterior Shaping (20 minutes)

  1. Start the lathe. Using the bowl gouge, true the outside diameter to a clean circle. Light cuts, working along the edge.
  2. Flatten the face (top of the blank) with a sweeping cut from the edge toward the center.
  3. Begin shaping the exterior profile: Starting at the rim (widest point), cut a flowing curve toward the base using the bowl gouge. Work in progressive passes, removing 1/8"-1/4" per pass.
  4. The exterior should have a smooth, continuous curve from rim to base—no flat spots or sudden transitions.
  5. Check the profile from the side. Compare to the design template.
  6. Leave the bottom flat area (approximately 2" diameter) for the tenon.

Phase 3: Tenon Creation (10 minutes)

  1. Measure the chuck jaw range on your scroll chuck. Record the optimal tenon diameter.
  2. Using the parting tool, define the tenon diameter. Cut a groove just outside the tenon area to the full tenon height (3/8"-1/2").
  3. Using the bowl gouge or skew chisel, create the dovetail angle on the tenon wall. The undercut should match the chuck jaw profile (approximately 10°).
  4. Ensure the shoulder (flat area above the tenon where the jaw faces will seat) is flat and perpendicular to the tenon.
  5. Verify the tenon diameter with calipers. Test-fit on the chuck (with the lathe off and workpiece still on the faceplate).

Phase 4: Finishing the Exterior (7 minutes)

  1. Sand the exterior profile: 150, 220, 320 grit with the lathe running at 500 RPM.
  2. Do NOT sand the tenon area—it should remain as-turned for optimal chuck grip.
  3. Apply a light coat of sanding sealer or oil if desired.
  4. Remove from the faceplate. Mount in the scroll chuck by the tenon to verify fit and grip.

Discussion Points

  • Why do we shape the exterior before the interior?
  • What would happen if the tenon diameter was too small for the chuck jaws?
  • How does the dovetail angle increase holding strength?
  • What signs indicate the tailstock support can be safely removed?

Expected Outcomes

  • Bowl blank trued to round with smooth exterior profile
  • Properly sized tenon with dovetail angle matching chuck jaws
  • Flat, true shoulder for jaw seating
  • Sanded exterior ready for finishing

Assessment Rubric

Criteria Excellent (4) Proficient (3) Developing (2) Beginning (1)
Faceplate Mounting Centered, all screws tight, flat seating Minor offset, functional Noticeable wobble Unsafe mounting
Exterior Profile Smooth flowing curve, no flat spots Minor flat spot or bump Uneven curve Cannot achieve curved profile
Tenon Correct diameter, dovetail, flat shoulder Slightly over/under sized No dovetail, poor shoulder Cannot create a functional tenon
Finish Smooth, consistent sanding, no tool marks Minor tool marks remain Visible sanding scratches Rough, unfinished surface

Safety Considerations

  • Always use tailstock support during initial faceplate roughing
  • Stand to the side when starting the lathe with an unbalanced blank
  • Reduce speed if excessive vibration occurs
  • Never use the spindle roughing gouge for any faceplate operation
  • Face shield mandatory throughout all phases

Last Updated: 2026-03-19