Which figure runs along the cone's axis?

`n`, the mouth length. `z` runs across. It is the same rule as the rectangular tap on pipe, where the length follows the pipe's length — and it matters more here, because the two bites belong to different families: swapping the two figures does not give the same part rotated, it gives a different part.

Why are the four bites all different?

Because the cone changes radius with height. The two walls perpendicular to the cone's axis lie in planes of constant height, and such a plane cuts the cone in the very circle of that height: the bite is an exact arc, and the two arcs have different radii. The two parallel walls lie in planes of constant offset, and there the bite is a hyperbola. The part comes out deeper at the top than at the bottom.

Where do I measure c from?

From the cone's AXIS to the tip of the collar, the same datum as the cone branch. The guard asks it to clear the deepest bite, which is at the middle of the upper wall.

What about the hole in the cone?

That is the companion part, "Cone with Rectangular Hole" — and it is worth far more than the name suggests, because the hole is NOT a rectangle. Enter the same figures in both and the two patterns match.

Rectangular Tap on a Cone flat pattern

What it is

The rectangular collar seated on the wall of a truncated cone, its axis horizontal and crossing the cone's axis. It is the grille mouth and the chute on a conical hopper — the same part as the rectangular tap on pipe, but on a host whose radius changes with height.

Where it is used

Conical hoppers, silos, cyclone bodies, conical hoods, grille and chute mouths on any conical wall.

Measurements the calculation needs

D1 Diameter 1
D2 Diameter 2
H Height
N Outlet length
Z Outlet width
Y Measurement Y
C Branch length
DV Divisions
THK Thickness

Worked example

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

Diameter 1	400 mm
Diameter 2	1200 mm
Height	900 mm
Outlet length	300 mm
Outlet width	250 mm
Measurement Y	500 mm
Branch length	750 mm
Divisions	16
Thickness	4 mm
The flat pattern fits a plate of	1084 × 415 mm

Frequently asked questions

Which figure runs along the cone's axis?: `n`, the mouth length. `z` runs across. It is the same rule as the rectangular tap on pipe, where the length follows the pipe's length — and it matters more here, because the two bites belong to different families: swapping the two figures does not give the same part rotated, it gives a different part.
Why are the four bites all different?: Because the cone changes radius with height. The two walls perpendicular to the cone's axis lie in planes of constant height, and such a plane cuts the cone in the very circle of that height: the bite is an exact arc, and the two arcs have different radii. The two parallel walls lie in planes of constant offset, and there the bite is a hyperbola. The part comes out deeper at the top than at the bottom.
Where do I measure c from?: From the cone's AXIS to the tip of the collar, the same datum as the cone branch. The guard asks it to clear the deepest bite, which is at the middle of the upper wall.
What about the hole in the cone?: That is the companion part, "Cone with Rectangular Hole" — and it is worth far more than the name suggests, because the hole is NOT a rectangle. Enter the same figures in both and the two patterns match.

Measurements the calculation needs — Rectangular Tap on a Cone

Calculate a Rectangular Tap on a Cone

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