Square to round
Concentric square to round transition, laid out by triangulation. Enter the square, the round and the height; the true lengths are worked out for you, and the pattern points are given as measurements off the square edge.
Inputs
Actual size, including insulation
From the Knauf chart, or type your own
Straight up from the square to the round
01/16 of round circumference
0½ square side (B to C)
0True length A to 1 (seam)
True lengths from the corner
| Line | True length 1/16" | Decimal |
|---|
These are your divider settings from the apex of the right angle: B to 1 equals B to 5, B to 2 equals B to 4.
Pattern points, measured
| Point | Along B-B from left B | Up from B-B |
|---|
Same points as swinging arcs, given as a tape measurement: along the square edge from the left corner, then square up from it. Negative "along" is past the left corner; negative "up" is below the line.
Half pattern, to scale
- Draw B-B the length of one side of the square.
- From each end of B-B, swing the B-5 true length to find 5.
- Set dividers to (1/16 of the round) and swing left and right of 5. Cross them with the B-4 true length from the nearest corner to find 4. Carry on for 3, 2 and 1.
- From 1, swing the A-1 true length. Cross it with ½ the square side from B to find C. Join B to C and C to 1 on both sides. That's half the transition.
- Add side laps, end laps to join the square, and notches to join the round. The other half is the same, with safety edges in place of the side laps.
Method: IIIATF Metal Layouts, Square to Round. Round centred on the square. Laps and notches are not included. Check the first piece before cutting a batch.