DIY Network

Woodturned Vessel: Hollowing the Center From "Wood Works" episode WWK-611

The curly maple used to create this hollow vessel is marked by spalting -- a fungal growth that creates vein-like lines through the wood.

With the outside shape of the turned vessel essentially complete, work can begin on hollowing out the vessel. In this segment, David Marks demonstrates the techniques used for turning the inside of a hollow vessel.

Tools and Materials Featured in this Episode:

Black walnut stock
Curly maple stock
Lathe: One-Way 2436 model
Lathe accessories
(live tail center; 4-way spur chuck; 4-jaw chuck, etc.)
Band saw
Various gouges and turning tools
(straight boring bar, angled boring bar, diamond parting tool, etc.)
Air compressor and hose
Double-ended caliper
Dental light
Awl
Chalk
Sandpaper
Carpenter's pencil
Face shield
Protective woodturning coat

Safety Alert: Always wear safety goggles or safety glasses, and follow proper safety precautions, when working with wood, power-tools, saws, drills, routers, etc.

Safety Apparel for WoodturningFor safety, wear a face shield when to protect your eyes and face from flying chips. A turning jacket, that seals at the neck, helps keep chips from getting down your shirt. Ski gators will prevent chips from getting down your socks and into your shoes.

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Figure A

Prep for Boring the Center

• The 4-jaw chuck is mounted on the head stock and closes down on the tenon cut earlier near the base. This provides a secure support as you begin hollowing out the center. Bring the jaws together to grip the tenon securely.

  Tip: The live center can be used in the tail stock to hold the vessel in place to ensure that the vessel is centered as you tighten the 4-jaw chuck (figure A). A true centered piece of stock will not wobble when turned.
  

  	Figure B
  	Figure C

  
  

• To support the other side of the vessel, David uses a center-steady (figure B). (David custom-made this one using a specially cut wood frame, metal bracket-arms and inline skate wheels, -- but center-steadies are also available commercially.)

  The center-steady mounts on the bed of the lathe and has wheels mounted on adjustable bars to support the work piece (figure C). The objective is to hold the top side of the vessel in place while you are applying lateral pressure during the turning process. The steady supports the stock and prevents the wood from deflecting as you're cutting.
  

  
  

• Before you begin work with the hollowing tools, it's a good idea to take a drill bit and drill out the center, down to the final depth of the vessel. This will make hollowing a lot easier. A piece of tape on the drill bit can serve as a depth gauge to ensure that you drill to the proper depth (figure D).

• First, lay the drill bit on the tool rest to assist in getting the hole started.

• Then remove the rest, and carefully drive the bit into the hole, making incremental pushes until the hole is bored to the final depth of the vessel (figure E).

  Figure D

  Figure E

  
  

  
  

• Now that you've drilled a hole down the center, you're ready to begin hollowing. This is a process that is done in stages. For the first phase, you'll bore into and clear out the center section of the vessel (figure F) using a straight boring-bar.

• The tip of the straight boring-bar (figure G) is made from high-speed steel and is 1/4" square.

  Note: Turning tools typically come without handles. David custom turned his own tool handles. The straight boring bar has a 30" handle made from myrtle. Copper banding a the top of the handle strengthens the connection and prevents the handle from splitting under pressure.

  Figure F

  Figure G

  
  

  
  
  

• To begin boring, position the tool rest about 1-1/2" inches from the vessel (figure H).

• Starting at the entrance, hollow around the center -- widening the opening (figure I). Slowly push in, then out, pulling out the sawdust at the same time. Bore the hole to about 4 to 5 inches.

  Figure H

  Figure I

  
  

  
  

• The second phase of the boring process is to bore out from the center to define the inside shape of the vessel (figure J) using a angled boring bar.

• The tip of this boring bar is angled at 45 degrees (figure K) and is made from high-speed steel so that it will hold a cutting edge for a long time.

  Figure J

  Figure K

  
  

  	Figure L
  	Figure M

  
  

• Using the angled tool, carefully widen the sides inside the vessel to create more working area (figure L).

• Since you'll be "cutting blind" -- unable to see the cutting edge of the tool as it cuts -- the lines on the handle help indicate the position of the cutter. On this tool, the black line facing up indicates that the cutting tip is level.

• For this phase, straddling or sitting on the lathe will give you added leverage and stability.

  Important: Never enter a cut with the tool cutter rotated above horizontal. As seen in the inset of the illustration (figure M), the tip could easily jam or catch.

  Tip: Clean sawdust out of the hole using compressed air as you go. Centrifugal force can force shavings to the sides of the vessel so that they get in the way of the cutting action.
  

  
  

• As you progress, it's a good idea to check your work periodically with a bright light to see how far you've advanced (figure N).

• The third phase consists of hollowing out the shape to the edge and defining the thickness of the wall (figure O), again using the angled boring-bar. For this phase in particular, be very careful as a careless move could break through the wall and ruin several hours of work.

  Figure N

  Figure O

  
  

  
  

• For this phase, rather than straddling the lathe for leverage, you'll need to stand off to one side to better position the bar at the appropriate angle (figure P). Work toward the wall, establishing the proper thickness, then move back to the center of the hollowed area to begin the next cut.

• Continue working in this manner, taking careful measurements periodically as you go using a double-ended caliper and ruler (figure Q). We cut until the vessel wall was uniform at about 3/16"

  Figure P

  Figure Q

  
  

  
  

RESOURCES :

The Small Wood Shop (The Best of Fine Woodworking)
Author: Helen Albert (Editor)
Publisher: Taunton Press
ISBN: 1561580619

Woodworking Techniques: Best Methods for Building Furniture from Fine Woodworking
Author: Editors of Fine Woodworking magazine
Publisher: Taunton Press
ISBN: 1561583456

David Marks Website
David Marks, DIY's Wood Works host, is a master woodworker. For more information on cut sizes and project details, please contact him via his Website at www.djmarks.com