Reference Section > Shape Library > Round Shapes

The Notched Disk is a round disk with a rectangular notch cut in from one side. The notch is a straight-sided slot with a square end; its two walls meet the circle at the mouth of the notch. Use it for a disk that has a slot or a flat cut into one edge. With Notch Width set to 0 there is no slot: the shape is a disk with a single straight flat (a D shape).

It appears in the shapes library under Round Shapes.

Insert point and direction

The insert point (Base X, Base Y) is the lower corner of the notch mouth – the point where the lower wall of the notch meets the circle. The notch opens to the left: its walls run in the +X direction, Notch Width long, and are Notch Height apart, so the upper mouth corner is directly above the insert point. The disk lies to the right of the insert point. Its centre is Notch Height / 2 above the insert point and ½ √(Diameter² − Notch Height²) to the right of it.

The profile is one closed path: from the insert point along the lower wall of the notch, across the square end of the notch, back along the upper wall to the circle, then clockwise round the circle (the larger part of the circle, not the part that the notch removes) back to the insert point. Use Rotation in the Transform properties to point the notch in another direction.

Notch Height is dimensioned across the notch mouth, Notch Width along the lower wall of the notch (zero length when Notch Width is 0), and Diameter vertically across the disk through its centre.

Properties

Property	Description	Default
Diameter	Diameter of the disk (length, mm or inch). A value of 0 builds a single point at the insert point instead of a profile.	100 mm (4 in)
Notch Height	Width of the notch across its mouth, i.e. the distance between its two walls (length, mm or inch). It is also the length of the chord where the circle is cut by the mouth line through the insert point. The part of the circle on the far side of that chord, away from the disk centre, is never part of the profile. The edit box minimum is 0.1. Must not be greater than Diameter (see Limits).	25 mm (1 in)
Notch Width	Depth of the notch in +X (length, mm or inch), measured from the mouth of the notch (the line through the insert point) to the square end of the notch. A value of 0 gives no notch: the circle is closed by a straight flat between the two mouth corners.	40 mm (1.6 in)

Limits

•Notch Height greater than Diameter is not a valid shape, and the result depends on the build. In a release build the value is not checked: the sine of the half-angle (Notch Height / Diameter) is clamped to 1, so the profile is a half circle whose diameter is Notch Height, and Diameter does not control the profile. In a debug build an assertion fails instead: no profile is built, and a red bar reading Warning: Cannot build shape from these parameters appears on the property page, between Notch Width and the Transform properties. Keep Notch Height no greater than Diameter. Notch Height equal to Diameter builds a half disk (before any notch is removed).

•Notch Width is not checked against the disk. If it is greater than √(Diameter² − Notch Height²), the notch end lies beyond the far side of the circle and the profile crosses itself. No warning is shown in this case. Keep Notch Width less than that distance.

•A negative Notch Width puts the rectangle on the outside of the circle, so the disk gets a rectangular tab instead of a notch.

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.