Double Cut Cylinder flat pattern
What it is
A rolled shell cut at an angle on both ends, each with its own angle. Developed, it gives two waves — one per edge — which can differ in height and phase. It is the part that clears two offsets with a single length of tube.
Where it is used
Connecting runs between misaligned equipment, intermediate gores of field-assembled bends, adaptations to existing pipework.
Measurements the calculation needs
- D Outside diameter of the tube
- X Straight run between the two cuts
- ANG1 Cut angle of the first mouth
- ANG2 Cut angle of the second mouth
- DV Divisions
- THK Plate thickness
Calculate with your own measurements
No account needed: enter the measurements in millimetres or inches and get the figures and the drawing. The scaled PDF template, the DXF for the cutting table and the 3D model take a free account.
Diameters and sides are outside measurements. The flat pattern already allows for the plate thickness, working on the mean line.
Units: mm inches
Worked example
The values the form comes pre-filled with, run through the tool itself:
| Outside diameter of the tube | 7-7/8" (7.874) |
|---|---|
| Straight run between the two cuts | 3-15/16" (3.937) |
| Cut angle of the first mouth | 35° |
| Cut angle of the second mouth | 35° |
| Divisions | 16 |
| Plate thickness | 3/8" (0.3937) |
| The flat pattern fits a plate of | 23-1/2" × 7-3/8" |
| Flat patterns produced | 2 |
Result of the example
| Plate 1 | 23-1/2" × 7-3/8" |
|---|---|
| Area and weight | 0.77 ft² · ≈ 12.4 lb in 3/8" steel |
| Plate 2 | 23-1/2" × 7-3/8" |
| Area and weight | 0.77 ft² · ≈ 12.4 lb in 3/8" steel |
Ordinate table
| # | Position on the plate | Element height |
|---|---|---|
| 1 | 0" | 2-1/8" |
| 2 | 1-7/16" | 2-5/16" |
| 3 | 2-15/16" | 2-7/8" |
| 4 | 4-3/8" | 3-3/4" |
| 5 | 5-7/8" | 4-3/4" |
| 6 | 7-5/16" | 5-3/4" |
| 7 | 8-13/16" | 6-9/16" |
| 8 | 10-1/4" | 7-1/8" |
| 9 | 11-3/4" | 7-5/16" |
| 10 | 13-1/4" | 7-1/8" |
| 11 | 14-11/16" | 6-9/16" |
| 12 | 16-3/16" | 5-3/4" |
| 13 | 17-5/8" | 4-3/4" |
| 14 | 19-1/8" | 3-3/4" |
| 15 | 20-9/16" | 2-7/8" |
| 16 | 22-1/16" | 2-5/16" |
| 17 | 23-1/2" | 2-1/8" |
Assembly notes
Weld the sheets with the longitudinal seams 180° apart, not lined up. Lined up, the piece assembles into a different shape — and the longitudinal seam crosses the circumferential one.
Guides about this part
Frequently asked questions
- Do both angles have to match?
- No. Each opening takes its own angle, which is the point of the part: solving two different offsets in one cut of plate.
- Why does the result come in two flat patterns?
- The part is delivered as two halves that together close the tube. Each half can be checked separately against the single-cut cylinder.
You can work out the figures right here, with no account. PDF, DXF, 3D and history take an account — free, with unlimited calculations.