The Hole Pattern (PCD) is a ring of holes on a pitch circle diameter (PCD) with no outline of its own – a bolt circle to place on any part. The holes can be round holes, straight slots or slots curved along the PCD. They can be spaced evenly round the full circle, or spread over part of it from a Start Angle through an Included Angle. Each hole is a separate closed profile, so the pattern is normally placed inside a part outline, for example to add a bolt circle to a plate.
It appears in the shapes library under Basic Shapes, Round Shapes and Flanges.
Hole Pattern (PCD) in PrimeShape: the property page (left) and the shape with its dimensions (right).
Insert point and orientation
The centre of the PCD is Offset X, Offset Y from the insert point. With both offsets at 0 (the default) the insert point is the PCD centre.
The first hole is at Start Angle, measured anticlockwise from the X axis as seen from the PCD centre. The other holes follow anticlockwise:
•With an Included Angle of 360° the holes are spaced evenly round the full circle, 360° / Hole Count apart. The last hole does not land on the first.
•With an Included Angle of less than 360° the first hole is at Start Angle and the last at Start Angle + Included Angle, so the holes are Included Angle / (Hole Count - 1) apart.
Every hole or slot is centred on its position on the PCD.
Properties
Lengths are in the current units (mm or inches) and angles in degrees. The defaults shown are for a new shape; the inch defaults are used when the program is set to inches.
Property |
Description |
Default |
Hole Type |
The shape of each hole: Round hole, Slot (a straight slot, laid as Slot Direction) or Curved slot (a slot bent along the PCD). A slot with a Slot Length of 0 is cut as a round hole. |
Round hole |
Hole Count |
Number of holes on the PCD, from 1 to 1000. |
6 |
PCD |
Pitch circle diameter the hole centres lie on, centred Offset X, Offset Y from the insert point. Must be greater than 0, and greater than Hole Dia for curved slots. |
150 mm (6 in) |
Start Angle |
Angle of the first hole, measured anticlockwise from the X axis as seen from the PCD centre. Negative values are allowed and turn the first hole clockwise from the X axis. |
0° |
Included Angle |
Angle from the first hole to the last, anticlockwise. 360° spaces the holes evenly round the full circle; less spreads them from Start Angle to Start Angle + Included Angle, with a hole at each end. Must be greater than 0° and no more than 360°. Has no effect on the spacing when Hole Count is 1. |
360° |
Hole Dia |
Diameter of the round holes, or the width of the slots (which is also the diameter of their round ends). Cannot be negative. If Hole Dia is 0 no holes are cut; a single point is placed at each hole centre instead. |
12.5 mm (0.5 in) |
Slot Length |
Length of each slot from the centre of one end arc to the centre of the other, so the overall length of a straight slot is Slot Length + Hole Dia. For a curved slot it is measured along the PCD. Cannot be negative; 0 gives round holes. Not used when Hole Type is Round hole. |
25 mm (1 in) |
Slot Direction |
Which way a straight slot lies: Across the radius (at right angles to the line from the PCD centre, tangent to the PCD) or Along the radius (lying on the line from the PCD centre, so it points at the PCD centre). Used only when Hole Type is Slot. |
Across the radius |
Offset X |
Distance of the PCD centre from the insert point along X. Positive moves the pattern right, negative moves it left. |
0 |
Offset Y |
Distance of the PCD centre from the insert point along Y. Positive moves the pattern up, negative moves it down. |
0 |
The dimensions drawn on the shape are named after these properties, and clicking one edits that value. PCD is drawn half way between the first two holes, Hole Dia on the first hole (on its far end for a slot), Slot Length along the first straight slot, Start Angle from the X axis to the first hole, Included Angle from the first hole to the last, and Offset X and Offset Y from the insert point to the PCD centre. A dimension that does not apply is hidden: Hole Dia when it is 0, Slot Length for round holes and curved slots, Start Angle when it is 0° or a whole number of turns (360°, -360° and so on), Included Angle for a single hole or a full circle, and an offset when it is 0.
Limits
The shape is checked every time it is built. If any of these conditions is broken the shape is not built. It is then drawn as a broken-shape marker at its insert point, and the property page shows a red bar reading Warning: Cannot build shape from these parameters. That warning does not name the condition, so check the values against this list:
•Hole Count must be 1 to 1000.
•PCD must be greater than zero.
•Hole and slot sizes cannot be negative – Hole Dia and Slot Length.
•Included Angle must be over 0 and no more than 360 degrees.
•PCD must be bigger than Hole Dia for curved slots. Checked when Hole Type is Curved slot and Slot Length is more than 0; a curved slot with a Slot Length of 0 is a round hole and is not checked.
•The holes overlap - reduce Hole Dia or Hole Count, or increase PCD – neighbouring round holes touch or cross. When the holes do not go all the way round, the gap from the last hole back round to the first is checked too.
•The slots overlap - reduce Slot Length, Hole Dia or Hole Count – two slots touch or cross. Straight slots are checked against every other slot, not only their neighbours; curved slots are checked against their neighbours along the PCD.
•Slot Length is too long to curve round the PCD – a curved slot would span the whole PCD, or it spans more than 180 degrees and its two ends come within Hole Dia of each other.
The pattern has no outline, so nothing checks it against the part it is placed on. Make sure the holes lie inside the part outline and leave enough material between the holes and the edge for the material and process you will cut with.
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.