Guides · Fittings
Lobster back: what the app does with it
What you give it, what it prints, and the two guards that stop a bad radius reaching the sheet.
You give it
| Input | How |
|---|---|
| Pipe | Nominal bore or OD, from the chart or typed |
| Insulation | mm; cladding is worked to the outside of it |
| Bend angle | Any |
| Segments | Any count; end pieces are half segments |
| Centre radius | 1D, 1.5D, 2D, 3D, 5D off the nominal bore, or typed |
| Seam | Anywhere on the 12-point dial; 7 is back, 4 is side |
| Lap and swage | From Settings; the lap splits half each side of the seam |
It gives you
- Every segment developed on its own and stacked seam-edge left, the way the cut sheet goes. It never unrolls the bend as one sheet.
- Cut line, fold lines, lap on the seam edge, rivet holes on the seam lines both edges, swage line at every mitre, plain end on the end pieces.
- Printed 1:1 on A4 or A3, tiled with crosshairs, 100 mm bar on every sheet. DXF if you cut on plasma or laser.
- A 3D of the bend with the seam marked, that unwraps into the same pattern you are about to print.
It refuses
- A centre radius inside the cladding radius. The throat would cross itself; the app says so instead of printing it.
- A fractional segment count. It rounds down and tells you.
Print at 100 percent, not fit to page. Rule the 100 mm bar. Offer the first segment up before you cut the run.