Twisted Spires
Education
Only for Mac
Free
Mac
Archimedean Spiral, a Logarithmic Spiral, or a 6th Root Spiral
This Mac app can be used to rapidly create twisted spire drawings of an Archimedean Spiral, a Logarithmic Spiral, or a 6th Root Spiral, or to compare all three spirals.
For a full, detailed explanation on how to develop and build the twisted spire, see my book:
HG V Twisted Circular Work in Carpentry Stereotomy Geometry
https://www.raftertools.com/twisted-spire.html
First, select the type of twisted spire for the drawing, then the radius of the cone and the height of the cone. Then you can select the helix rotation angle and plan view arc angle for the ray spacing in plan view, as well as the calculated ray spacing on the developed surface. The Top Radius is only used for a logarithmic spiral. The Mat. Width is the twisted spire material width.
Top Toolbar buttons:
Show projection lines from profile view level lines to plan view axis.
Show arcs from the axis to each spiral–ray intersection in plan view.
Show rotated contour polygons connecting corresponding spiral intersections in plan view.
Polygon: repeats the spiral at each corner of the selected polygon
Show twisted-spire edge curves on the developed surface
Show twist-block rectangles on the profile view
Show Spiral measuements table for plotting
Export the drawing as a PDF, JPG, DXF, or SketchUp .dae file to import into SketchUp.
Slant = length of the slant line of the cone profile
Sector = the developed surface arc angle
Dev. Ray = arc angle of each ray on the developed surface
Spiral ψ° = logarithmic constant slope angle
φ^(1/6) = 6th root of the golden ratio = 1.083505
Golden Ratio = 1.618033988749
Also, see my book for the parallellogram technique for shaping the twisted spire material.
The export SketchUp is saved as a .dae file for import inot SketchUp, but here are other programs that can open Collada .dae files:
CAD / 3D Modelling
- SketchUp Pro (2017+) — File › Import
- Rhino 3D — native import
- Blender — File › Import › Collada
- Autodesk Maya — native import
- Autodesk 3ds Max — via importer plugin
- Cinema 4D — File › Merge
Viewers / Converters
- MeshLab — free, open source
- FreeCAD — File › Import
- Open3D — free viewer
- Autodesk Viewer (online, viewer.autodesk.com) — drag and drop
Game Engines
- Unity — drag into Assets folder
- Unreal Engine — import pipeline
Online
- 3D Viewer Online (3dviewer.net) — free, browser-based
- Autodesk Viewer — free, browser-based
Converting to Other Formats
- Blender can convert .dae → .obj, .fbx, .stl, .glb
- FreeCAD can convert .dae → .step, .iges, .dxf
- MeshLab can convert .dae → .obj, .ply, .stl
The most useful for the workflow is likely SketchUp (open as .dae, save as .skp) or Blender (free, can convert to any format).
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The developer, Sim Ayers, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
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Information
- Seller
- Sim Ayers
- Size
- 7.4 MB
- Category
- Education
- Compatibility
Requires macOS 26.0 or later.
- Mac
Requires macOS 26.0 or later.
- Mac
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © Sim Ayers 2026