Sheet metal and fabrication layout tools
Layout tools for sheet metal, plate and duct work. Each tool gives the numbers, a full-size template you can print on ordinary paper, and DXF/SVG files for plasma, laser or waterjet cutting.
Cone flat pattern calculator
Flat pattern for cones, truncated cones and reducers, with a full-size printable template.
- Full-size PDF template
- DXF
- SVG
- Mark-out table
Square to round transition calculator
Square or rectangle to round transitions and hoppers, centred or offset, with a full-size template and a true-length table.
- Full-size PDF template
- DXF
- SVG
- True-length table
Which tool for which shape?
| Shape | Also called | Method | Tool |
|---|---|---|---|
| Cone, truncated cone | Frustum, concentric reducer, hopper cone, funnel | Radial lines (arcs about the apex) | Cone flat pattern calculator |
| Offset cone | Eccentric reducer, flat-back reducer, oblique cone | Triangulation | Cone calculator, eccentric mode |
| Square or rectangle to round | Transition, square to round duct adapter | Triangulation | Square to round transition calculator |
| Rectangle to rectangle | Hopper, pyramid frustum | Flat faces (true shapes) | Transition calculator, hopper mode |
| Hemisphere or dome | Orange-peel dome, cap, dome cladding | Gores | Sphere and dome pattern generator |
| Cylinder | Pipe, straight duct | A rectangle π × D long | Cone calculator with equal diameters |
Problems these tools solve
- "I need the radius and angle to lay out a reducer."
- The cone calculator gives the outer and inner radius and the sweep angle from the two diameters and the height. The cone flat pattern formula guide shows the working by hand.
- "The radius is too long to swing on my bench."
- Draw the chord and set the arc off at stations from a chord-offset table. The calculator gives the table; the cone guide shows how to use it.
- "My reducer has to be flat on one side."
- That is an eccentric reducer, developed by triangulation rather than arcs: see eccentric reducer layout.
- "I need a transition from a rectangular fan outlet to round duct."
- Enter the rectangle, the round and the height (and any offset) in the transition calculator. The square to round layout guide explains the true-length table it gives you.
- "My pattern is bigger than my printer paper or my sheet."
- Every tool tiles the full-size PDF across A4 or Letter pages with registration marks, and can split the pattern into equal pieces that fit a sheet.
Before you cut
- Material thickness: lay out rolled shapes on the mean (mid-thickness) diameter. Each tool asks whether you measured the inside, outside or centre of the metal and converts.
- Allowances: seam (lap) and end allowances are added outside the finished outline, which stays marked so you can see the true edge.
- Printing: print templates at 100% / Actual size and measure the ruler on page 1 before trusting them. DXF files are true size with their units declared.
Guides
- Cone flat pattern formula and how to lay it outThe formulas behind a cone or frustum pattern, a worked example, and two ways to mark it out on the metal.
- Eccentric reducer layout by triangulationWhy an offset reducer needs triangulation, with a worked true-length table and its flat pattern.
- How to lay out a square to round transitionTriangulating a square or rectangle to round, centred or offset, with a worked true-length table.
Related categories
Balls and domes in fabric or foam, using the same gore maths, are in crafts and printables. Workshop build planners for wood are in woodworking and DIY.