The Pole Base with polygonal hole is a rectangular base plate for a polygonal pole or column. Each of the four corners has a round-ended slot running diagonally in towards the centre, for the anchor bolts, and a regular polygon (an octagon by default) is cut through the plate for the pole. The edges where the slots meet the outside of the plate are filleted. A matching shape with a round hole, Pole Base with Hole, is also in the library.
It appears in the shapes library under Rectangular Shapes and Gussets. It has no formerly-named versions.
Pole Base with polygonal hole in PrimeShape: the property page (left) and the shape with its dimensions (right).
Insert point and orientation
The insert point is the bottom left corner of the plate (0, 0). Width is built to the right along X and Height upwards along Y. Each slot runs in from its corner along the 45° diagonal, so the slot centres are on the diagonals of the plate. On a plate that is not square the slots do not point at the centre.
With both offsets at 0 the centre of the polygon is at the centre of the plate, (Width / 2, Height / 2) from the insert point; the offsets are added to that position. The polygon always has one flat at the bottom, parallel to X. With an even number of sides there is also a flat at the top; with an odd number of sides there is a corner at the top.
Properties
The hole properties are listed first, then the plate properties. Lengths are in the current units (mm or inches). Defaults are shown in mm, with the inch value in brackets.
Property |
Description |
Default |
Num. of Sides |
Number of sides of the polygonal hole. Minimum 3 on the property page. For example 4 gives a square hole, 6 a hexagon, 8 an octagon. |
8 |
Flat to Flat |
Size of the polygonal hole. With an even number of sides it is the distance across flats, from the bottom flat through the centre to the top flat. With an odd number of sides there is no opposite flat, so it is the distance from the bottom flat through the centre to the top corner. If Flat to Flat is 0 no hole is cut; a single point is placed at the hole centre instead. The property page minimum is 0. |
100 mm (4 in) |
Offset X |
Moves the hole centre along X from the centre of the plate. Positive moves it right, negative moves it left. The hole size does not change. |
0 |
Offset Y |
Moves the hole centre along Y from the centre of the plate. Positive moves it up, negative moves it down. The hole size does not change. |
0 |
Width |
Overall width of the plate, along X, from the left edge to the right edge. |
200 mm (8 in) |
Height |
Overall height of the plate, along Y, from the bottom edge to the top edge. |
200 mm (8 in) |
Slot Depth |
Distance, measured along the 45° diagonal, from the corner of the plate to the centre of the slot's round end. The same value is used for all four slots. |
50 mm (2 in) |
Slot Dia |
Width of each slot, which is also the diameter of its round end. The slot opens onto the two plate edges at Slot Dia / √2 (about 0.71 × Slot Dia) from the corner, before the fillets. |
25 mm (1 in) |
Fillet Rad. |
Radius of the fillets where the slot sides meet the outside edges of the plate (eight fillets in all, two per slot). Each fillet's tangent length along the plate edge is 2.41 × Fillet Rad. At 0 the fillet is replaced by a sharp corner (a 0.01 mm minimum is used internally). |
6.25 mm (0.25 in) |
The dimensions drawn on the shape are Height, Width, Slot Depth, Slot Dia, Flat to Flat and the two offsets. The offsets are measured from the centre of the plate to the centre of the hole. Fillet Rad. is not dimensioned.
Limits
The shape code does not check the sizes against each other. Offset X and Offset Y accept negative values. Keep these conditions yourself:
•The two slots on each edge must not meet. The straight part of each edge runs between the fillet ends, so Width and Height must each be more than 2 × (Slot Dia / √2 + 2.41 × Fillet Rad.).
•Num. of Sides below 3 does not make a valid polygon. The property page enforces a minimum of 3.
•The hole must stay clear of the slots and of the outside edges. The corners of the polygon reach further from its centre than the flats do.
If a part cannot be built, the shape code catches the error and leaves out only that part: the plate outline is left out if the plate fails, and the hole is left out if the hole fails, so the other part is still drawn. The property page can then show the red bar Warning: Cannot build shape from these parameters.
Check the part outline after changing the slot, fillet or hole sizes. The shape does not report a slot, fillet or hole that overlaps another part of the outline, so an outline that crosses itself or a hole that touches a slot or an edge will not be flagged.
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.