Hubs Overview

Bring up the Struts & Hubs window by selecting the item ‘Hub properties...’ in the ‘Hubs’menu.

png

NOTE. The checkbox “Use persistence” and the field entry “Flange ingress” are only available with Geodesica-SFX 0-9-9-6 and later.

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.

Sphere Hubs

png sphere

Generic hub type.

Cylinder Hubs

png sphere

Generic hub type.

Ring Hubs

png sphere

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

png sphere

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

png sphere

Generic hub type

Start Flange Hubs

png sphere

png

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.

png png

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.

Flange Ingress Geodesica-SFX 0-9-9-6

This option is for Ring Flange and Star Flange hubs, and moves the flange in or out of the hub cylinder; if the flange is hinged with the hub, leave this setting at zero; but if the flange makes a solid union with the hub, enter a positive value to move the flange into the hub wall. The flange radius remains unaffected. This option was implemented for 3D printing and CSG unions which have yet to be implemented.

png png

png png

Below: the struts have no hub ingress applied, so that their ends are tangential to the hub cylinder; but the flanges have a positive hub ingress applied, so that their ends enter the hub wall:

png

Use persistence Geodesica-SFX 0-9-9-6

When checked, hub and struts attributes are saved and loaded from preferences and remain persistent between app sessions. This saves having to re-enter dimensions for a particular hub and strut type.