Why do I need this part and not just the nozzle?

Because the hole on the cone is neither a circle nor an ellipse on the flat pattern. It comes from the same intersection as the nozzle, mapped into the sector, and there is no way to mark it without the drawing.

Is the hole worked out the same way as the nozzle's mouth?

It is the same calculation, in the same place in the code. Both parts ask Base::BranchHole where one meets the other, and the spec checks it point by point — if they disagreed the hole would not match the mouth and no pattern would save it.

Where does the cone's seam go?

Diametrically opposite the hole. A longitudinal weld does not run through a cut-out.

Why is the hole larger than the nozzle's diameter?

Because the nozzle meets the cone obliquely, and the shallower the cone the more oblique the meeting. The hole is the cylinder projected onto the sloping surface, and it stretches along the slope.

Cone with Parallel-Axis Nozzle Hole development

What it is

The cone with the upright nozzle's hole already marked — the mate of the parallel-axis nozzle. Marking a hole on a cone by hand is far worse than on a cylinder, because the surface does not open into a rectangle and no tape will do.

Where it is used

The other half of the upright-nozzle job — hoppers, silos, cyclones, conical tank roofs.

Measurements the calculation needs

D1 Diameter of the smaller mouth (bottom)
D2 Diameter of the larger mouth (top)
H Height of the cone
D Outside diameter of the nozzle
V Offset from the nozzle axis to the cone axis
DV Divisions
THK Plate thickness

Worked example

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

Diameter of the smaller mouth (bottom)	400 mm
Diameter of the larger mouth (top)	3000 mm
Height of the cone	500 mm
Outside diameter of the nozzle	300 mm
Offset from the nozzle axis to the cone axis	1200 mm
Divisions	32
Plate thickness	6 mm
The flat pattern fits a plate of	3212 × 3177 mm

Result of the example

Plate	3212 × 3177 mm
Arc radii	213.1 mm · 1,606 mm
Sector angle	336°

Cone with Parallel-Axis Nozzle Hole flat pattern: drawing of the template with the worked example dimensions — Cut lines in purple, welds in green and reference lines in orange. Plate 3212 × 3177 mm.

Frequently asked questions

Why do I need this part and not just the nozzle?: Because the hole on the cone is neither a circle nor an ellipse on the flat pattern. It comes from the same intersection as the nozzle, mapped into the sector, and there is no way to mark it without the drawing.
Is the hole worked out the same way as the nozzle's mouth?: It is the same calculation, in the same place in the code. Both parts ask Base::BranchHole where one meets the other, and the spec checks it point by point — if they disagreed the hole would not match the mouth and no pattern would save it.
Where does the cone's seam go?: Diametrically opposite the hole. A longitudinal weld does not run through a cut-out.
Why is the hole larger than the nozzle's diameter?: Because the nozzle meets the cone obliquely, and the shallower the cone the more oblique the meeting. The hole is the cylinder projected onto the sloping surface, and it stretches along the slope.

Cone with Parallel-Axis Nozzle Hole dimension drawing: D1 (Diameter of the smaller mouth (bottom)), D2 (Diameter of the larger mouth (top)), H (Height of the cone), D (Outside diameter of the nozzle), V (Offset from the nozzle axis to the cone axis), DV (Divisions), THK (Plate thickness), marked on the part

Calculate a Cone with Parallel-Axis Nozzle Hole

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