gifStrut and Hub Intersections Part 3 - Star & Ring flange Hubs

Spaceframe Struts with a Hub Axis Shift

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If strut generation or intersection is OFF an error dialogue will appear when generating the hubs. An error dialogue will also appear if the struts and/or flanges fail to intersect with the hub. This can be caused by an exhorbitant hub shift, or by shifting the spaceframe ORG and/or DEST ends too far along the hub axis.

The following sequence shows a single spaceframe strut between an inner Dual hub (blue) and an outer Primal hub (green). In all cases, the following settings were used on both the 'ORG HUB INTR' and 'DEST HUB INTR' tabs:

    Hub intersect: ON
    Project strut ends to hub intersection plane: ON
    Elongate Hub intersection cylinder: OFF
   

1. No spaceframe shift. Strut intersects top of inner Dual hub and botton of outer Primal hub. (The hub cylinder radius has been shortened to make the flange ends visible).

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2. Postive shift applied to ORG end of strut at the Primal hub. Hubs not yet regenerated, so the flanges are misaligned.

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3. Primal and Dual hubs regenerated: Primal and Dual flanges now in the correct positions.

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3. Negative shift applied to DEST end of strut at the Dual hub. Hubs not yet regenerated, and flanges misaligned.

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4. Primal and Dual hubs regenerated: Primal and Dual flanges now in the correct positions.

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The above sequence shows that when you shift a strut at one end, you must regenerate hubs at both ends.

Before updating hubs or struts, you must change to the appropriate target. For example, if the current target is ‘Target A’, and the hubs to update are in ‘Target B’, you must first change to ‘Target B’ and then click ‘Apply Hubs’ on the Struts and Hubs window. Likewise, if the current target is ‘Target B’, and the struts to update are in ‘Target A’, you must first switch to‘Target A’ before clicking ‘Apply Struts’.

Star Flange Options

When you select 'Star Flange' on a Hub tab, two new check boxes appear:

Use Strut Width
Use Strut Height

When checked, the flange width and height are automatically set to the strut width and height. Thus Primal, Dual and Spaceframe struts can have different cross sectional profiles and the flange mortices will adapt accordingly:

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Ring Flange Options

When you select 'Ring Flange' on a Hub tab, a new check box appears:

    Use Strut Height
    

When checked, the flange height is automatically set to the strut height. This setting is important when spaceframe struts intersect the bottom or top of a hub; in which case the hub’s wall thickness can be increased to give enough surface area for the flange edge joints.

The flange width can now be set independently of the hub wall thickness. The flange width field is labelled 'u'.

CAVEAT. At the time of writing, the flanges belong to the hubs; but after implementing this, I realise that a better design solution would be for each strut to have its own flange type. Then different flange types could be attached to different hub types. This is something to consider for the future. One caveat with the current implementation is this:

If you change the radius of the hub core and click 'Apply Hubs' you must then click 'Apply Struts' to generate the new intersection planes for the flanges. Finally, you must click 'Apply Hubs' again to re-generate the flanges.

IMPORTANT: The hub angles printed in the log and the Plan window only refer to the quad-edges - they do not refer to shifted spaceframe struts which have their own independent hub plane; the angle data for this second hub plane is not currently shown in either the Plan Window or the Log.