Menu path
Tools > More... > Create Flat Pattern
🧾 What it does
The Create Flat Pattern command unfolds three-dimensional surfaces to produce cutting templates or flat patterns for manufacturing. It handles special roof features such as domes, spires, and tapered gutters, providing allowances for plate thickness and neutral axis depth for accurate, repeatable results.
The command can unfold flat planes, ruled surfaces, and cylinders. The Rul-Sur option specifically handles general ruled surfaces (excluding cylinders).
⚠️ Important limitations
Bend allowance: The Rul-Sur command provides no bend allowance provisions. The model represents the neutral surface, which works well when material is relatively thin compared to its extent (like tapered gutters).
Twisted surfaces: Ruled surfaces are constructed with rulings at equal spacing along two generator curves. Some surfaces are twisted as well as bent. Twisted surfaces cannot be unfolded without drawing or stretching material. The command still produces results, but the outline is an approximation.
Non-twisted surfaces: Surfaces are not twisted if:
One generator is a point
The two generators are always parallel (one is a scaled, translated copy of the other without rotation)
🔧 How to create a flat pattern
When you select the command, the system prompts for the ruled surface location near the edge to unfold:
Select the ruled surface by one of its straight edges at the end to start the unfold process from
Locate a point on the CPL (Construction Plane) to use as the corner of the unfolded surface
Locate another point to indicate the direction to unfold the surface
🛠 Reference points
Point | Description |
D1 | Locate ruled surface |
D2 | Position to unfold surface |
D3 | Direction to unfold surface |
💡 Direction control
The surface unfolds in the x-positive or x-negative direction depending on where you place the direction point (D3).
🧾 Pattern results
When unfolded, the flat pattern outline consists of two lines and two curves. The system does not automatically rotate other entities that depend on the ruled surface.
For complex patterns including multiple planes and unfolded ruled surfaces (such as a square-round duct transition), you must separately translate and rotate each unfolded surface and plane to combine them into a single pattern.