Practical tools for measured work
Oblique Cone Flat-Pattern Developer
Triangulate an offset-apex circular cone into a printable developed blank with true generator lengths.
Calculate the layout, check the diagram, then print the result for the shop or jobsite.
How it works
Measure height perpendicular to the base. Measure apex offset in the base plane from the circle center to the vertical projection of the apex.
The base is divided into chords and each triangular facet uses its true generator lengths. With the default 300 mm base, 400 mm height and 80 mm offset, the generators range from about 406.1 to 461.4 mm.
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Base diameter
- 300 mm
- Perpendicular apex height
- 400 mm
- Apex offset from center
- 80 mm
- Development divisions
- 36
Primary result: Longest generator: 461.41 mm.
Before using the result
- Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
- Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
- When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.
Limitations
This is a triangulated circular-edge approximation. More divisions produce a smoother edge but add layout lines. Add the seam separately, mark its orientation and verify a test pattern before production.
Frequently asked questions
What should I verify before using this result?
Recheck the physical measurements, confirm that every input uses the displayed unit, and compare the result with the applicable drawing, product specification, code requirement or test piece.
Why might the finished result differ?
Real work can include thickness, kerf, seams, tolerances, hardware allowances, installation clearances or site conditions that are outside the calculation. The limitations section identifies the main exclusions for this tool.
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