Reference Section > Shape Library > Round Shapes

The Ring shape is a round part with a round hole in the middle: an outer circle and an inner circle, both centred on the insert point. Use it for washers, spacers, collars and similar round parts. The hole can carry one or more keyways, which turns it into a keyed bore for a shaft.

It appears in the shapes library under Basic Shapes and Round Shapes.

Insert point and direction

The centre of both circles is the insert point (Base X, Base Y). The shape is two closed profiles: the inner hole, built first and anticlockwise, then the outer circle, built clockwise. With a keyway the hole is one closed path, also anticlockwise: out along one wall of each keyway, across its square end, back along the other wall, then round the bore to the next keyway.

ID is dimensioned on the inner circle and OD across the outer circle. With a keyway, Key Width is dimensioned across the end of the first keyway and Key Depth along its centre line.

Properties

Property	Description	Default
ID	Inside diameter – the diameter of the hole (mm or inch). An ID of 0 gives a single point at the insert point instead of a hole, but only while Keyway is None. With a keyway, ID must be greater than 0.	50 mm (2 in when working in inches)
OD	Outside diameter – the diameter of the outer circle (mm or inch). Must not be 0: an OD of 0 stops the shape being built (see below).	100 mm (4 in)
Keyway	Adds keyways cut outward from the hole, making it a keyed bore. None – plain round hole; Custom – Key Width and Key Depth as entered; Metric (DIN 6885) – width and depth taken from the DIN 6885-1 table for the ID; Inch (ANSI B17.1) – width taken from the ANSI B17.1 square key table for the ID, depth worked out from it.	None
Key Width	Width across the keyway (mm or inch). Must be greater than 0 and less than the ID. Used as entered for Custom; for Metric and Inch it is replaced by the table value when the shape is built.	6.25 mm (0.25 in)
Key Depth	How far the keyway goes beyond the bore circle, measured radially on the keyway centre line (mm or inch). The keyway end is at a radius of ID/2 + Key Depth, so along the keyway centre line the hub, from the bore on the opposite side to the keyway end, measures ID + Key Depth (the DIN 6885 t2 convention). Must be greater than 0. Used as entered for Custom; replaced by the table value for Metric and Inch.	2.5 mm (0.1 in)
Keyway Angle	Direction of the first keyway centre line, anticlockwise from +X (degrees). Each further keyway is spaced 360° / Keyway Count round from it.	90° (straight up)
Keyway Count	Number of keyways, spaced evenly round the hole starting at Keyway Angle. The property page enforces a minimum of 1; a value above 1000 stops the shape being built.	1

Key Width, Key Depth, Keyway Angle and Keyway Count have no effect while Keyway is None. Parts saved before the keyway was added open with Keyway set to None and keep their plain round hole.

Standard keyways

With Metric (DIN 6885) or Inch (ANSI B17.1) the keyway size is looked up from the ID each time the shape is built, and written back into Key Width and Key Depth so you can see the values used. Key Depth is then applied in the same way as a Custom depth, measured radially from the bore circle.

•Metric covers bores over 6 mm up to 500 mm. Both width and depth come from the table.

•Inch covers bores over 5/16 in up to 6 1/2 in. The table gives the key width. The keyseat is half the square key deep at its side walls; Key Depth is that depth on the centre line, i.e. half the key width less the height of the bore arc across the keyway.

When the shape cannot be built

If the values cannot make a valid shape, the shape shows a broken-shape marker at the insert point, and the property page shows Warning: Cannot build shape from these parameters. On the Ring this happens when OD is 0, or with a keyway when:

•ID is 0 or less (a keyway needs a bore greater than zero);

•Keyway is Metric or Inch and the ID is outside the range of the table;

•Keyway Count is less than 1 or more than 1000;

•Key Width is 0 or less, or is not less than the ID;

•Key Depth is 0 or less;

•there is more than one keyway and neighbouring keyways overlap – use fewer or narrower keyways;

•the outer corners of a keyway reach the outer circle (the keyway would break through the outside of the ring) – reduce Key Depth or Key Width, or increase OD.

Without a keyway the shape does not check ID against OD. An ID equal to or larger than the OD still builds, as two circles that do not make a usable ring, so check that ID is smaller than OD.

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.