Reference Section > Shape Library > Round Shapes

The Flat-Cut Ring (Diameter) shape is a ring (washer) given by its outside and inside diameters, with a straight flat cut across the bottom. The flat removes a segment of the ring of a set height, measured up from the bottom of the outside diameter. A shallow flat leaves a ring with a flat edge and the hole intact; a flat deep enough to reach the hole cuts through it and leaves a horseshoe-shaped part with the hole open through the flat. Use it for a ring that must have a flat on one side.

This shape was formerly called Partial Ring 2 (Diameter); searching by the old name still finds it. The Flat-Cut Ring (Radius) shape builds the same part from radii instead of diameters.

It appears in the shapes library under Round Shapes.

Insert point and direction

The common centre of the outside and inside diameters is the insert point (Base X, Base Y). The flat is always horizontal and below the centre when Cut Height is less than half the OD; it lies at Cut Height above the bottom of the OD, that is at OD/2 − Cut Height below the insert point. Use the Rotation property to turn the flat to another side.

How the profile is built depends on whether the flat reaches the hole:

•Cut Height up to (OD − ID)/2 – the flat stays outside the hole. The part is two paths: the full ID circle (the hole) and an outer profile that starts at the left end of the flat, runs over the top of the OD arc to the right end of the flat, and returns along the flat. With Cut Height 0 there is no flat and the outer profile is the full OD circle, giving a plain ring.

•Cut Height greater than (OD − ID)/2 – the flat cuts through the hole. The part is one closed path: from the left end of the flat on the OD, over the top of the OD to the right, along the flat to the hole, back over the top of the hole to its left side, then along the flat to the start.

The ID and OD dimensions are drawn as diameters about the centre. Cut Height is dimensioned vertically from the bottom of the OD circle up to the flat.

Properties

Property	Description	Default
OD	Outside diameter of the ring (mm or inch).	100 mm (4 in)
ID	Inside diameter of the ring, i.e. the hole diameter (mm or inch). Must be less than OD.	50 mm (2 in)
Cut Height	Height of the segment removed by the flat, measured from the bottom of the OD up to the flat (mm or inch). 0 gives a full ring with no flat; values above (OD − ID)/2 take the flat through the hole.	37.5 mm (1.5 in)

Limits

The shape does not check its values against each other, so keep them in range yourself:

•ID must be less than OD. The shape does not check this. An ID equal to or larger than OD gives an outline that is not a usable part.

•Cut Height must be 0 or more, and no greater than (OD + ID)/2, the height at which the flat reaches the top of the hole. Outside this range the outline needs the arccosine of a value outside −1 to 1, which has no real result. The shape does not check the range itself, so check the drawn shape and the property page after changing Cut Height.

If building the outline raises an error, building stops at that point, the shape's extents collapse to the insert point, a broken-shape marker is drawn at the insert point, no dimensions are built, and the property page shows a red bar reading Warning: Cannot build shape from these parameters.

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.