Truncated Cylinder flat pattern

What it is

A rolled shell cut on an inclined plane at one end. Developed, the cut edge becomes a sine wave: its height comes from the cut angle and its length from the circumference of the shell.

Where it is used

Pipe entering an inclined wall, discharge openings, column feet cut to floor angle, roof penetrations.

Measurements the calculation needs

• D Diameter
• Y Measurement Y
• ANG Angle
• DV Divisions
• THK Thickness

Worked example

The values the form comes pre-filled with, run through the tool itself:

Diameter	200 mm
Measurement Y	50 mm
Angle	40 mm
Divisions	16 mm
Thickness	10 mm
The flat pattern fits a plate of	597 × 214 mm

Frequently asked questions

What is measurement Y?

The height of the short side of the part, taken where the inclined cut meets the shell. The tall side follows from the angle you enter.

Why does the cut edge become a wave rather than a straight line?

Because when the cylinder is unrolled, every point on the inclined opening was at a different height. That variation, spread along the circumference, traces exactly a sine wave.