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CAD tip CAD tip # 12237:

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Q - question

UnfoldRS - unfold 3D surfaces to 2D in AutoCAD.

A - answer Similar to Inventor (unfold, unwrap) or Fusion 360, also AutoCAD can unfold some types of unfoldable 3D objects/surfaces to 2D representation, e.g. for forming sheetmetal or glueing paper, textile or cardboard.

The freeware LISP application UnwrapRS can unfold ruled surfaces, i.e. objects created by the RULESURF command from border curves of any type. Typical examples are: conical surfaces - reducers between ducts of different diameter, transitions (transforms) circle-ellipse or ellipse-rectangle, facade building elements formed by two 3D splines, etc.

The rule surface must be generated in the legacy Polyline mode, i.e. with the MESHTYPE=0 setting. The precision of the surface (and then of its unfold) depends on the setting of the SURFTAB1 variable.

The result of the unfold is a planar representation of the object made of a group of 3D Faces and a group of outline curves circumventing the shape of the unfold (e.g. to be cut from sheetmetal).

You can download the UnfoldRS utility from, load it into your AutoCAD with APPLOAD and run by typing the UNFOLDRS command. Choose the Polyline mode and select a previously created rulesurf object. Enter the layer name for the unfold.

Unfolds cannot be used on twisted surfaces - you can avoid twits by rotating or 2D/3D mirroring of one of the source border curves. In the Face mode, you can also unfold individual 3D faces, but they must be created in the same way as in an exploded ruled surface.

Usage of the UnwrapRS utility:

This is a purely geometrical unfolding, without respecting material properties. Use Autodesk Inventor or Fusion 360 for advanced unfolding of 3D models, including K-Factor, etc.

100% *  CAD 
12.5.2019    329×  
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applies to: AutoCAD ·

See also:
Tip 11946:How to find net surface area (sans holes) of an unfolded sheetmetal part in Fusion 360?
Tip 11868:Open just a part of a DWG drawing - layers, views.
Tip 11720:How to export unfolded sheetmetal parts in Fusion 360?
Tip 11556:How to set K-Factor and other parameters for sheetmetal unfolding in Fusion 360?
Tip 10916:How to project unfolded flat pattern to a sketch?

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