Corners, transitions and compound geometry · Lesson 3 of 4

Corners, transitions and compound geometry: methods and worked application

Bisecting a corner, the half-angle rule and the saw-setting trap, three pattern development methods, then worked examples: a sloped run, a run between corners, and why corners go in first.

You will be able to: Find a miter angle and saw setting, choose a pattern development method, convert a sloped run to true length and split a run between corners into pieces, recording inputs and units.

10 min · 10 slides · 7 questions

All lessons in this module

Slide 1 of 10

Bisect the corner

The miter line runs along the bisector, the line that splits the corner angle in two. BCcampus draws it with a compass:

Swing an arc from the vertex across both sides
From each crossing, swing equal arcs that meet
Draw a line through the vertex to where the arcs meet

Sources

Pattern Development: Sheet Metal Level 1 - Bisect an Angle (2021, CC BY 4.0) - BCcampus (Brian Coey)

Glossary

Bisector: The line that splits an angle into two equal halves; a miter joint runs along it.
Parallel line development: A pattern method for parts whose bend lines are parallel and whose two ends are the same shape.
Radial line development: A pattern method whose element lines radiate from one point, for right cones and pyramids.
Triangulation: Locating each new point from two known points; it develops transitions such as square to round.
Stretch-out: A perimeter laid out straight, as the flat length of a pattern.
Allowance: Extra material added for a seam or other component, outside the stretch-out.