Why will the cone with an ordinary branch hole not do?

Because a conical tap reaches the wall already flared — that is what it is for — so the hole is larger and a different shape. The difference is stronger here than on a pipe, because both surfaces open out at once: the hole runs deeper at the top, where the cone is wide, and that is precisely where the tap is widest too.

Do the hole and the tap mouth agree?

They do, by construction. Both parts ask the same calculation, in the same place in the code, about where one surface meets the other. If they disagreed the hole would not fit the mouth — which is why the intersection is not written twice.

Why mark the hole before rolling?

Because marking a hole on a cone by hand is far worse than on a cylinder — the surface does not open into a rectangle, and there is no way to transfer the measurement without the sector. With the plate still flat the layout is direct.

Can the hole be marked from the collar diameter?

No. The collar is the free end, the smaller one; what crosses the wall is the section of the tap THERE, which is larger. Marking from the collar gives a hole that is too small, and the gap grows with the taper and with the length.

Cone with Conical Tap Hole development

What it is

The pair of the conical tap on a cone: that part gives the template for the TAP, this one for the cone it enters. Enter the same tap in both and you have both templates for the job. With this pair the catalogue's branch matrix is complete on both rows — the branch and the hole — for all six branch-and-host combinations.

Where it is used

The hopper, silo or cyclone wall that receives a conical nozzle, marked out before rolling.

Measurements the calculation needs

D1 Smaller diameter of the cone
D2 Larger diameter of the cone
H Height of the cone
D Diameter of the nozzle collar (smaller mouth)
D3 Diameter of the nozzle notional base, on the cone axis
Y Height of the nozzle axis above the cone base
C Length, from the cone axis to the collar
DV Divisions
THK Plate thickness

Worked example

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

Smaller diameter of the cone	300 mm
Larger diameter of the cone	900 mm
Height of the cone	800 mm
Diameter of the nozzle collar (smaller mouth)	200 mm
Diameter of the nozzle notional base, on the cone axis	300 mm
Height of the nozzle axis above the cone base	500 mm
Length, from the cone axis to the collar	700 mm
Divisions	32
Plate thickness	6 mm
The flat pattern fits a plate of	2274 × 1085 mm

Result of the example

Plate	2274 × 1085 mm
Arc radii	419.2 mm · 1,273.6 mm
Sector angle	126.4°

Cone with Conical Tap 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 2274 × 1085 mm.

Frequently asked questions

Why will the cone with an ordinary branch hole not do?: Because a conical tap reaches the wall already flared — that is what it is for — so the hole is larger and a different shape. The difference is stronger here than on a pipe, because both surfaces open out at once: the hole runs deeper at the top, where the cone is wide, and that is precisely where the tap is widest too.
Do the hole and the tap mouth agree?: They do, by construction. Both parts ask the same calculation, in the same place in the code, about where one surface meets the other. If they disagreed the hole would not fit the mouth — which is why the intersection is not written twice.
Why mark the hole before rolling?: Because marking a hole on a cone by hand is far worse than on a cylinder — the surface does not open into a rectangle, and there is no way to transfer the measurement without the sector. With the plate still flat the layout is direct.
Can the hole be marked from the collar diameter?: No. The collar is the free end, the smaller one; what crosses the wall is the section of the tap THERE, which is larger. Marking from the collar gives a hole that is too small, and the gap grows with the taper and with the length.

Cone with Conical Tap Hole dimension drawing: D1 (Smaller diameter of the cone), D2 (Larger diameter of the cone), H (Height of the cone), D (Diameter of the nozzle collar (smaller mouth)), D3 (Diameter of the nozzle notional base, on the cone axis), Y (Height of the nozzle axis above the cone base), C (Length, from the cone axis to the collar), DV (Divisions), THK (Plate thickness), marked on the part

Calculate a Cone with Conical Tap Hole

An account is required. The free tier covers 20 calculations a month.