Reference Section > Shape Library > Round Shapes

The Partial Ring (Radius) shape is a segment of a ring: an outer arc and an inner arc on the same centre, joined at each end by a straight radial edge. Use it for curved segments, C-shaped parts, and ring sectors that are joined to make a larger ring. With IR set to 0 it becomes a pie-shaped sector. The same part sized by diameters is the Partial Ring (Diameter) shape.

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

Insert point and direction

The centre of the two arcs is the insert point (Base X, Base Y). The insert point is on the part only when IR is 0, where it is the apex of the sector. With IR above 0 the centre lies in the hole.

The segment is always placed symmetrically about the line straight down from the centre (-Y), so the opening faces up (+Y). This is a "smiley face" orientation, which nests better. The outer arc starts at 270° less half the Swept Angle and runs anticlockwise through the Swept Angle. Use Rotation in the Transform properties to turn the opening to another direction.

The outline is one closed path, built anticlockwise: along the outer arc, in along the radial edge at its end, back along the inner arc (clockwise), then out along the other radial edge to the start. With IR = 0 the two radial edges meet at the centre and there is no inner arc.

IR and OR are dimensioned as radii from the centre. Swept Angle is dimensioned as an angle at the centre.

Properties

Lengths are in the current units (mm or inch). Angles are in degrees. The defaults are for a new shape.

Property	Description	Default
IR	Inner radius (mm or inch). Minimum 0. At 0 there is no inner arc and the part is a sector (pie slice) with its point on the insert point.	25 mm (1 in)
OR	Outer radius (mm or inch). The property page sets no minimum. It should be larger than IR; the shape does not check this (see Notes and limits).	50 mm (2 in)
Swept Angle	Angle the segment covers, measured at the centre (degrees). Maximum 360°. The property page sets no minimum. The gap left in the ring is 360° less the Swept Angle, centred on +Y.	300°

Notes and limits

•The shape does not check that IR is less than OR, and no warning is shown if it is not. If IR is larger than OR, the arc at IR becomes the outer edge and the arc at OR the inner edge. The outline still closes, with no warning. Check the drawing before cutting.

•A Swept Angle of 360° is not special-cased. Both radial edges then lie on the +Y line and overlap, so the result is one closed outline with a zero-width cut at the top. For a complete ring with no split, use the Ring shape.

•If the outline cannot be built from the values entered, the property page shows the red bar "Warning: Cannot build shape from these parameters" and no outline is produced. The shape does not validate the values before building, so it fails only where a geometry routine raises an error.

The Cut Ring shape is built from this shape with the Swept Angle fixed at 360°. Its property page lists IR and OR only, with no Swept Angle property.

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.