Truss tube attachment
This drawing shows how the trusses are attached to mirror box and secondary cage. The trusses themselves are 10x10x1.25mm aluminium U-profiles, with the open side pointing outward. The trusses have holes at their extremities, that fit snugly over a M4 hex bolt head. These hexbolts are used to fix the attachment points of the trusses.
It is important to locate these points very precisely, and also to drill the holes in the U-profiles repeatable over the trusses, so that there is no need to number them and still keepo collimation between setups. This may be undoable with the required precision, and then a numbering scheme can still be used.
The trusses slide over the bolts, and still need to be clamped down. These clamps are flat pieces of aluminium for the cage side, and L brackets for the mirror box side. A total of 8 screws is needed for clamping.