Bring up the Struts & Hubs window by selecting the item ‘Hub properties...’ in the ‘Hubs’menu.
IMPORTANT. Because regenerating struts and hubs is CPU intensive, there are two seperate buttons ‘Apply Struts’ and ‘Apply Hubs’. Strut regeneration is not automatic because it is often desirable to ‘tweak’ the hub properties until the desired form is obtained. However, to correctly compute hub/strut intersections, you MUST regenerate struts when you have change the hubs. Conversely, you MUST regenerate the Hubs when you have changed the struts.
Hubs come in various types which are suited to different construction methods.
Generic hub type.
Generic hub type.
This hub type is used with strut fixings that “clip” onto the ring or bolt through it. The ring is generally made from steel. Ideally the clip mechanism incorporates a pivot which adjusts to the strut angle.
Ring Flange Hubs
The flange “tennons” slot into “mortices” in the struts. The flange width is the same as the hub wall width. Ring flange hubs are generally made from steel, and the struts from wood. The struts are fixed to the flanges with bolts. You can control the number of divisions between flanges (the roundness of the hub) by changing the number of slices. Here the struts intersect with the hub circumference and the strut ends are parallel to the hub normal.
Right Angled Cone Hubs
Generic hub type
Start Flange Hubs
Intended for rectangular [edge] and square [edge] strut types. The dimension 'u' is the top flange width which is typically equal to the strut width. The dimension 'd' is the side flange height and this is typically equal to the strut depth. Conceivably, it is possible to rout channels in the top of the strut for the flange sides, in which case the flange width and height would use smaller dimensions. The UI for Star Flange hubs also includes inputs for the strut height and width.
Slices and Stacks
Depending on the hub type, you can change the hub mesh resolution using the ‘Slices’ and ‘Stacks’ counters. The ‘Stacks’ counter is only visible when using spherical hubs.
The default value for slices is 24. Note that the slice value has no effect on intersection queries; the intersection code uses perfect spheres, cylinders and cones. The slice counter is simply used to control resolution of the output model. High slice and stacks values will slow down OpenGL redraw when using legacy graphics cards with limited RAM.