Pipe Mitered both ends is a length of pipe with each end cut on a flat angled plane (a miter). PrimeCut builds the pipe in 3D and produces its flat development: the blank you cut from flat plate and roll into the pipe. Use it for a pipe or duct section that has to fit between two angled flat surfaces, or for one piece of a segmented (lobster-back) bend.
It appears in the shapes library under Thick Walled Developments and Pipe Development Shapes. The pipe cutter version, Pipe Cutter - Pipe Mitered both ends, is a separate shape. Its defaults differ: it has 360 segments, no fold lines (Show Bends off) and a Neutral Axis Fraction of 1, so it develops on the outside diameter.
Pipe Mitered both ends in PrimeShape: the property page (left) and the shape as a wireframe with its dimensions (right).
Insert point and how the shape is built
In 3D the pipe stands on its axis (Z). The bottom miter plane passes through the origin and the top miter plane crosses the axis at Pipe Length above it, so Pipe Length is measured along the centre line between the two miters. Each miter plane is tilted from square by its Miter Angle. With Spin Top Angle 0 both planes tilt about the same axis, so with equal angles the two ends are parallel, as in the picture below. Spin Top Angle turns the top miter around the pipe axis relative to the bottom one.
The pipe is divided into Dev. Segs flat facets around its circumference. The facets are unrolled at the neutral axis diameter (set by Neutral Axis Frac(K Factor)) to give the flat blank:
•The blank is unrolled from a seam at the Development Start Angle around the pipe.
•The insert point is the top end of that seam. The seam runs along +X to the bottom end, and the circumference runs along –Y, one neutral axis circumference (π x neutral diameter) long.
•The two cut paths are the two ends of the blank: the top end on the insert point side and the bottom end on the +X side. Each is one open path of Dev. Segs straight lines. The sides of the blank (the seam) are not produced as cut paths.
The dimension text OD is Up, Fold Down on the blank gives the rolling direction: the outside of the pipe is the upper face of the plate.
Each segment of the two end cuts carries a bevel angle, worked out from the height difference between the outside and the inside of the wall at that point, so that a bevel head cuts through the wall on the miter plane. Where the miter plane is square to the wall the bevel is 0.
Properties
The properties are listed in the order the property page shows them. A 3D development shape has no Polar Array properties.
Property |
Description |
Default |
Top Miter Angle |
Angle of the top end plane from square to the pipe axis (degrees). 0 gives a square end. A negative value tilts the plane the other way. |
45° |
Spin Top Angle |
Turns the top miter plane around the pipe axis, relative to the bottom miter (degrees). At 0 the two miters tilt about the same axis; at 180° they tilt in opposite directions. |
0° |
Bottom Miter Angle |
Angle of the bottom end plane from square to the pipe axis (degrees). 0 gives a square end. A negative value tilts the plane the other way. The bottom miter has no spin of its own; turn the top miter with Spin Top Angle instead. |
45° |
Pipe OD |
Outside diameter of the finished pipe (mm or inch). Minimum 1. |
900 mm (35.43 in) |
Pipe Wall Thickness |
Wall thickness of the pipe, normally the plate thickness (mm or inch). The inside diameter is Pipe OD – 2 x Pipe Wall Thickness. Minimum 1. |
50 mm (1.97 in) |
Neutral Axis Frac(K Factor) |
Where in the wall the pipe is unrolled, as a fraction of the wall thickness measured from the inside: 0 = inside diameter, 0.5 = middle of the wall, 1 = outside diameter. The blank length is π x (inside diameter + K Factor x 2 x Pipe Wall Thickness). Use 0.5, or your rolling K factor, for a blank rolled from flat plate. Range 0 to 1. The value is stored in the shape under the name Neutral Axis Fraction. |
0.5 |
Pipe Length |
Length of the pipe centre line, from where it meets the bottom miter plane to where it meets the top miter plane (mm or inch). The length at any other point around the pipe is longer or shorter than this, depending on the miter angles. |
1500 mm (59.06 in) |
Development Start Angle |
Position around the pipe of the seam where the blank is unrolled, that is the edge that is joined after rolling (degrees). With the default 90° and Spin Top Angle 0 the seam is where both miter planes are level with the axis, so the seam is Pipe Length long. |
90° |
Dev. Segs |
Number of flat facets around the circumference. Each end cut is made of this many straight lines, and Show Bends draws one fold line between each pair of facets. Minimum 3. |
240 |
Show Bends |
When ticked, the blank also carries a fold line across it between each pair of facets, as a guide for rolling or folding. Fold lines are marking paths, not cuts. |
Ticked |
Bend Length (0 for Full) |
Length of the fold-line marks at each end of each fold line (mm or inch). A fold line is shortened to two marks of this length only when it is longer than 2.1 x Bend Length; shorter fold lines are marked full length. 0 marks every fold line full length. Only used when Show Bends is ticked. Minimum 0. |
12.5 mm (0.49 in) |
The dimensions drawn on the 3D shape are Height (Pipe Length), OD, Angle (the Top Miter Angle) and the leader note OD is Up, Fold Down. The Bottom Miter Angle is not dimensioned.
Limits and errors
•No minimum or maximum is set on the Top Miter Angle or Bottom Miter Angle. At 90° the miter plane is parallel to the pipe axis and no end can be formed.
•Pipe Length must be long enough that the two miter planes do not cross inside the pipe. The shape does not check this; with steep miters on a short pipe the ends overlap and the blank is not valid. Check the 3D view before cutting.
•The inside diameter is Pipe OD – 2 x Pipe Wall Thickness. The shape does not check that the wall is less than half of Pipe OD, so a thicker wall gives a zero or negative inside diameter.
•Neutral Axis Frac(K Factor) is held between 0 and 1 by the property page. Pipe OD and Pipe Wall Thickness have a minimum of 1. Dev. Segs has a minimum of 3. Bend Length has a minimum of 0.
•A high Dev. Segs count gives a smoother end cut but many more lines, and with Show Bends ticked many more fold marks.
•If building the shape raises an error, the 3D pipe is cleared and the property page shows Warning: Cannot build shape from these parameters until the values are corrected. Check the 3D view before cutting.
The shape has no aliases (no former names). This shape also has the Transform properties (Base X, Base Y, Rotation, Scale, Mirroring X), listed after its own properties. As a 3D development shape it has no Polar Array properties.