Segmented Bowl Planner

Profile → Ring Stack → Miter Cut List

Getting Started with the Segmented Bowl Planner

This planner turns a bowl shape into a stack of glue-up layers, each a ring of mitered segments or a solid disc, ready to turn on a lathe. It gives you the miter angle, segment length, strip width and strip length for every ring, checks that each layer has enough glue contact with the next, lets you paint a pattern in different woods, and helps you correct your saw when a test ring doesn't close.

How to use it

  1. Start from a preset (Classic Bowl, Shallow Platter, Vase, Hollow Form) or the default shape.
  2. Shape the profile on the Profile & Rings tab by dragging the handles. The Height and Max Diameter fields in section 1 scale the whole shape.
  3. Set your stock and saw in section 2: layer thickness, segments per ring and saw kerf.
  4. Set the turning numbers in section 3: the final wall, floor thickness, turning allowance and the least glue contact you'll accept.
  5. Check the alert at the top of the sidebar and the Glue-Up Summary. Layers that need attention show in red on the profile.
  6. Paint a pattern on the Pattern & 3D tab (optional): pick a brush wood, then click or drag across the grid. Click a layer label to fill the whole layer, or start from a template. The preview shows the turned bowl, with each segment's grain and the glue lines between them; drag it to turn it.
  7. Go to the shop with the Cut List (printable). You can change the segment count for a single layer there, for example to use fewer, longer segments near the foot.
  8. Dry-fit a test ring, and if it leaves a gap, use the Miter Check tab to work out the new saw setting.
  9. Save your work with Save Project: name it, set its status (Backlog, In progress or Complete) and add notes. Press Save again as you make changes. Projects lists your saved bowls, and My Projects in the site menu lists every calculator's. Projects are kept in this browser, on this device.
  10. Share with Copy link: the link opens a copy of this design for whoever you send it to. Reset starts over with the default design.

Key terms

Profile
The outside shape of the bowl from foot to rim, drawn as a smooth curve through the handles. The inside follows it at the final wall thickness.
Layer
One slice of the stack, one stock thickness tall. L1 is the bottom layer, at the foot.
Ring
A layer made of identical trapezoid segments glued into a polygon. Its flats cover the turned outside and its inside corners stay clear of the turned inside.
Disc
A layer with no hole, or one too small to make from segments (under 1" across). Cut it from a single board or a glued-up panel.
Miter angle
The saw angle on each end of a segment: 180° ÷ segments. Twelve segments need 15°.
Outer length
The long side of each segment, long point to long point. Set your stop block to it.
Strip width
How wide to rip the board each ring's segments are cut from.
Strip length
Total strip needed for one ring, including one saw kerf per segment, before any test cuts.
Turning allowance
Extra wood left on the outside and inside of every ring, to turn away when you true up the bowl.
Glue contact
How much one layer overlaps the layer above, measured across the wall. Too little and the joint is weak, or the wall turns through.
Brick-lay offset
Turning every other ring by half a segment, so its joints land in the middle of the segments below, like bricks in a wall.

Assumptions

  • All measurements are in inches, and angles are in degrees.
  • Every layer is the same thickness. The bowl's height is rounded up to a whole number of layers, so the top layer may stand a little proud of the rim.
  • Every ring is a regular polygon of identical segments. Segments are cut alternately from one strip, flipping it between cuts.
  • The final wall is measured square to the profile. Below the floor thickness the bowl is solid.
  • Segments shorter than 1" on the long side are flagged as unsafe to cut; use fewer segments on that layer.
  • Board feet are net. The summary adds 25% for waste, and strip lengths leave nothing for setup or test cuts.
  • Wood colors and grain in the pattern and preview are approximate; real boards vary.
  • The miter check assumes every cut is off by the same amount, so the gap spreads evenly over all the miter faces.
Open this guide again any time with the Getting Started button.
Presets:

Profile & Ring Stack

Drag handles to reshape
L1 ·discL2 ·12L3 ·12L4 ·12L5 ·12L6 ·12r 1.750" · h 0.000"r 2.600" · h 0.600"r 3.400" · h 1.600"r 3.850" · h 2.800"r 4.000" · h 4.000"Stack 4.50" · Rim ⌀8.00"
Outside profile Inside (final wall) Ring stock (at segment flats) Needs attention