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The Partial Ring (Diameter) is a segment of a flat ring (an annulus): an outer arc and an inner arc on the same centre, joined at each end by a straight radial cut. It is used for ring segments and split rings. The ring is sized by its inside and outside diameters and the angle it sweeps. With the inside diameter set to 0 the shape becomes a pie sector.

It appears in the shapes library under Round Shapes. It has no aliases (alternative names).

Insert point and orientation

The insert point is the centre of the ring. The ring is symmetrical about the vertical (Y) axis: the swept angle is centred on straight down, so the material is at the bottom and the open gap faces up (+Y). With the default 300° the gap at the top is 60° wide. Use Rotation in the Transform properties to point the gap another way.

The outline is one closed path. It starts at the left-hand end of the outer arc, runs anticlockwise round the outer arc, cuts in along the right-hand end, runs clockwise back round the inner arc, and cuts out along the left-hand end.

Properties

Lengths are in the current units (mm or inches); angles are in degrees. The defaults shown are for a new shape; the inch defaults are used when the program is set to inches.

The dimensions drawn on the shape are ID and OD (as diameters) and the Swept Angle.

Limits

The shape does not check that the values make sense; keep these conditions yourself. If the geometry cannot be built, the property list shows a red "Warning: Cannot build shape from these parameters" line after the shape's own properties, above the Transform group.

•OD must be larger than ID. The shape does not compare them: with ID equal to OD the two arcs lie on top of each other and the part has no width, and with ID larger than OD the inner and outer arcs swap places.

•Swept Angle should be greater than 0. The property has a maximum of 360° but no minimum.

•At 360° the two end cuts lie on top of each other at the top of the ring, so the part is a full ring with a single radial cut of zero width. For a complete ring with no split, use Ring instead.

The end cuts are radial – each one lies on a line through the centre of the ring, so the angle between the two cuts equals the Swept Angle. At 180° the two cuts lie on one straight line through the centre, giving a flat cut across the ring.

Every 2D shape also has the Transform properties (Base X, Base Y, Rotation, Scale, Mirroring X) and the Polar Array properties, listed after the shape's own properties.