Reference Section > Shape Library

A 2D shape from the shapes library can be repeated round a pitch circle – a ring of holes or slots on a bolt circle, for example – using the five Polar Array properties. The shape and all its copies are one shape: editing any of the shape's own properties changes every copy.

In PrimeShape and PrimeCut the property page lists the shape's own properties first, then the Transform group, then the Polar Array group. The group is shown only for 2D shapes. It is not shown for 3D shapes, pipe shapes, Marking Text, Point, Strips or Blank Part.

Polar Count is 1 by default, which means no array. Shapes and parts saved before the polar array existed open with a count of 1 and are unchanged.

Properties

Property	Description	Default
Polar Count	Total number of copies on the pitch circle, including the shape as built. 1 turns the array off. The least allowed is 1 and the most is 1000.	1 (off)
Polar PCD	Pitch circle diameter (mm or inch): the diameter of the circle the centres of the copies lie on. Must be greater than 0.	100 mm (4 in)
Polar Start Angle	Angle of the first copy – the shape as built – seen from the pitch centre, in degrees anticlockwise from +X. It decides on which side of the shape the pitch centre lies (see below). Negative values are allowed.	0°
Polar Included Angle	Angle the copies are spread over, in degrees, from the start angle anticlockwise. 360° spaces the copies evenly round the full circle. Must be over 0° and no more than 360°.	360°
Polar Rotate Copies	True turns each copy about the pitch centre by the same angle as its position, so a radial slot stays radial on every copy. False only moves each copy round the circle without turning it, so every copy keeps the orientation of the first.	True

The metric default is shown above; in inches the default PCD is 4 in.

Where the copies go

The shape is built from its own properties exactly as it would be without an array, and stays where it is as the first copy. Its own dimensions stay on this first copy.

The pitch centre is then placed from the centre of the first copy's extents – the middle of the box that just encloses it. The pitch centre is half the PCD away from that point, positioned so that, seen from the pitch centre, the first copy lies at the Polar Start Angle. With a start angle of 0° the pitch centre is half the PCD to the left (−X) of the shape; with 90° it is half the PCD below it.

The other copies follow anticlockwise round the circle:

•Included angle 360° – the copies are spaced 360° ÷ Polar Count apart, and no copy lands on top of the first. Six copies are 60° apart.

•Included angle less than 360° – the copies are spread from the start angle to start + included angle, with the first copy at one end and the last copy at the other. They are spaced included angle ÷ (Polar Count − 1) apart: four copies over 90° are 30° apart.

The Transform properties act on the shape and all its copies together – see Shape Transform Properties. Rotation turns the whole array, Scale also scales the PCD, and Mirroring X reverses the direction the copies run in.

The PCD dimension

When the array is on, a diameter dimension is drawn across the pitch circle, starting from the side opposite the first copy. It is named Polar PCD: click it and enter a new value to change the Polar PCD property, the same way as the shape's own dimensions.

Limits

The PCD and the included angle are checked only when Polar Count is 2 or more. If a limit is broken, the property page shows the red banner Warning: Cannot build shape from these parameters. The banner does not say which value is wrong. The shape as built is still drawn, but the copies are not placed. The dimensions are not rebuilt while the error stands, so the drawing keeps the dimensions of the last good build, including any Polar PCD dimension, until the value is corrected.

•Polar Count must be 1000 or less. It cannot be set below 1.

•Polar PCD must be greater than 0.

•Polar Included Angle must be over 0° and no more than 360°.

The array does not check whether copies overlap each other. If the PCD is too small for the shape and count, the copies cross each other – check the drawing before cutting.