Turning a Segmented Bowl

Sue Harker makes a laminated open segmented bowl by gluing half rows of open segments to two half bowl blanks.

Handcrafted wooden bowl with intricate design.

Open segment turning holds a special interest for me. I’m always trying to think of other ways to introduce them as an accent into my turning. The inspiration for this particular bowl came from seeing a donut-shaped bowl turned from multi-coloured lengths of timber, laminated to create the bowl blank. Looking at the bowl I could visualise one of the lengths of timber being replaced by rows of open segments. Traditionally, open segment bowls are made with segment rows running parallel to the base and not through the base as with this bowl. 

The prototype bowl was constructed from several lengths of timber I had in the workshop.  As with all laminations it’s important for all the gluing surfaces to be totally flat and the segment strip needs thicknessing at the same time to minimise thickness discrepancies. Using one of my 18 open segment wheels and half rows of segments I constructed several rows of segments and glued all the pieces together to create a bowl blank. This prototype gave me the opportunity to overcome any problems I may encounter without wasting precious bowl blanks.

Handy hints

1. When following a pattern like the one shown in this article, it’s advisable to check you have correctly placed the segments in the segment wheel by sitting the bowl blank, with row(s) already glued, over the top of the segments.
2. Before sanding the bowl, check for any glue gaps. These can be filled with superglue
mixed with timber dust. To avoid staining, coat the surrounding area with oil before applying the glue/dust mix.
3. When turning the laminated bowl blank into the round start, the lathe at a low speed. For this blank the lathe was set at approximately 250rpm until the timber was more balanced.

Hand applying material between wooden blocks
To assist in positioning the segment rows more accurately, measure the width of one of the segment to find the centre and mark 2.5mm either side. These two marks will represent the gap between the segments on the row already glued to the bowl blank. The best segment space for this to be placed is in wheel position 4
Wood pieces arranged in radial pattern
To enhance the appearance of the finished bowl ensure the segments are placed with the direction of grain facing the same way. To do this select the segments required to form the half ring and sit them next to each other, as shown in the photograph, so you can check the direction of grain

Equipment and materials

Tools

  • Full face respirator
  • Dust extraction
  • Planer/thicknesser
  • Bandsaw
  • Vernier callipers
  • Steel rule
  • 18 segment wheel
  • Clamping jig
  • Clamps
  • Rotary sander
  • Drill with sanding arbor fitted
  • Proxxon carver with flat carving blade fitted
  • 20mm standard grind bowl gouge
  • 6mm standard bowl gouge
  • 3mm parting tool
  • Negative rake square edged scraper

Materials

  • Zebrano bowl blank – 230mm diameter x 50mm
  • Sycamore bowl blank – 190mm diameter x 40mm
  • One length of zebrano (Microberlinia brazzavillensis) – 50 x 50 x 300mm cut into segment strips – 7mm thick x 42mm wide
  • Two lengths of sycamore (Platanus spp.) – 50 x 50 x 300mm long cut into segment strips 7mm thick x 42mm wide
  • Titebond Moulding and Trim Woodglue
  • Abrasive discs 120, 180, 240, 300, 400 grit
  • Cyanoacrylate adhesive
  • Finishing oil
Diagram of segmented wooden bowl dimensions and materials.
Open Segment Pattern with Zebrano and Sycamore
Hands working on woodturning project.
1. Run a bowl blank of zebrano 230mm diameter x 50mm through a thicknesser to smooth both surfaces. Mount on the lathe and true up  the edge, then cut in half along the length grain
Measuring wooden crafts with calliper tool.
2. Place one half on an 18 open segment wheel and measure between two of the ‘spokes’ where the timber sits. For this bowl the measurement is 37mm. This is the width of segment required to clad the bowl half
Cutting wood on a bandsaw
3. Transfer the segment measurement to the bandsaw by securing the rip fence 37mm from the blade and set the angle mitre to 10°. Using the strips of timber prepared earlier cut 21 zebrano and 39 sycamore segments if you choose to follow the pattern I have used. This is done by passing the wood through the blade then turning the strip over and passing through the blade again
Bandsaw cutting wooden board
4. For the half segments cut the 10° angle on the segment strip, then set the angle mitre to zero and set the rip fence to 18.5mm from the blade. Cut the angled section off. Repeat this process for three zebrano and three sycamore half segments
Circular woodworking project with numbered slots
5. For the first row of open segments nine of the sycamore segments are used. Place them in segment spaces, one through to nine on the open segment 18 wheel and coat with glue. The glue I use is Titebond moulding and trim woodglue, which dries clear and has a 30 minute clamp time
Wooden segmented clock assembly in progress.
6. Place the zebrano half on top of the segments and ensure the bowl blank is squarely positioned; to do this, place a couple of segments in segment positions 18 and 10 and sit a 5mm thick small board of wood along the spokes
Person assembling a wooden project with screw.
7. Place in a clamping jig and apply downwards pressure. Clean out the surplus glue and leave in the clamp for 30 minutes
Wooden circle with radial segments in glue-up.
8. For the next row some half segments will be needed. Place eight full-size segments in the wheel in numbers one through to eight, following the segment pattern. Position two half segments in positions nine and 18: here you can see halves of different colours have been used to highlight the half segments. Coat with glue leaving a strip down the centre of the segments as this will be where the gap between the segments on the first row will sit
Hand placing wooden piece in segmented turntable.
9. Position the bowl half with one segment row attached over the segments aligning with the half circle. Place the small 5mm board of timber across the face to assist with alignment. Apply clamped pressure  for approximately 31 minutes
Assembling a wooden clock face with numbered sections.
10. The segments for row three are all full-sized segments and are placed in segment positions one through to nine. Here you can see the direction of the grain being checked with the previous row
Hand holding semi-finished woodwork piece
11. Continue with the segment pattern for a further four rows – seven rows in total. For row seven, only sycamore segments are used to match row one. Coat them with glue and align the other half of the zebrano bowl blank over them. Place under clamped pressure for approximately 30 minutes
Woodworking project with clamps and wood pieces.
12. Next, glue the two sycamore half bowl blanks to either side of the segment laminated zebrano bowl blank. This is best done one at a time using clamps to apply the pressure needed. To assist with alignment place the flat side of the blank on a flat surface and use clamps to apply the pressure needed. Repeat the process with the second sycamore half and leave to cure for at least 24 hours before turning
Woodturning on a lathe machine
13. Using a 100mm diameter by approximately 25mm thick piece of timber turn a sacrificial chucking spigot the correct size for the jaws being used. Mark the centre point and draw a line through it
Wooden gear with arrows and screws.
14. Mark the central position where the sacrificial chucking spigot is to be placed. Apply super glue to the front face of the sacrificial chucking spigot and activator to the surface of the laminated blank. Use the line drawn through the centre to align and hold down for a few seconds.  Leave to cure for a short time before pre-drilling pilot holes and fastening securely with two screws
Close-up of woodturning process with a lathe.
15. Loosely secure the sacrificial chucking spigot now securely fitted to the laminated bowl blank in the chuck with large jaws fitted. Bring up the taildrive and locate in the centregap between the segments and tighten. The chucking spigot might move slightly within the jaws as the bowl blank aligns itself more centrally. Now tighten the chuck to secure the bowl blank in place
Woodworking lathe turning a wooden piece
16. Leaving the taildrive secured in place for additional support, turn the bowl blank into the round using a 10mm standard grind bowl gouge. Next, shape the underneath of the bowl and foot
Woodturning on lathe in workshop
17. Refine the foot and cut a chucking spigot the correct size for the jaws being used. This will be used for remounting the bowl to shape the inside
Woodturning on a lathe with a tool.
18. Sand the bowl using a rotary sander, starting with 120 grit and working through 180, 240, 320 and finishing with 400 grit
Person working with wood lathe machine.
19. Remove the screws from the sacrificial chucking point and remount the bowl blank using the chucking spigot cut earlier.Using a 10mm standard grind bowl gouge turn away the sacrificial chucking point and true up the front face
Person shaping wood on a spinning lathe.
20. Remove the timber from the centre of the bowl as you would a standard bowl blank, taking extra care when cutting across the gaps. If too much force is applied to the cut the tool will knock and impair the cut: here you can see the wall thickness of the first 25mm of the bowl being refined
Woodturning on a lathe in a workshop
21. Work down the bowl in step cuts until the wall thickness is even throughout. Sand the inside of the bowl using the same grits as before. Clean out the dust between the segments or if you have a compressor, attach an air gun and blow out the dust, ensuring you are wearing the appropriate dust protection
Wooden bowl being machined with a drill
22. To remove the chucking spigot mount a small bowl blank on the lathe and turn it into a similar profile to the inside of the bowl.  Lay a piece of non-slip router matting over the dome and position the segmented bowl over.  Bring up the taildrive and locate in the original hole used for the first mounting. Tighten the taildrive to centralise the bowl.  Rotate the lathe by hand to check how true the bowl is mounted, re mount if required. Tightening the taildrive will create a friction drive for the foot to be removed
Woodturning on a lathe close-up
23. Using a 6mm standard grind bowl gouge gently turn away the excess timber leaving a pip large enough to still support the bowl. Sand the accessible area using the same grits as before. Remove from the lathe and remove the pip with a carving tool and then sand to a satisfactory finish
Handcrafted wooden bowl with intricate design
24. To finish apply several coats of finishing oil to the entire bowl, taking particular care between the segments. When totally dry the bowl can be buffed with Tripoli compound applied to a polishing wheel for the outside and a polishing mop for the inside

Further reading

Using Pewter in Turning

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