Hello again Greg,
I haven't built nor used a wire spider myself, but I'll offer the following thoughts:
- I would be concerned about relying on a single point of friction (ie. set screw at right angles) to reliably hold the spider, especially when it is not getting any extra leverage on the wire (eg. having a few turns of wire wound around an anchor).
- I'm not sure how tough the wire is, but pinching it in this manner can also damage it, so you may find your spider going 'twang' at some point.
- The threads in the aluminium rod (for the set screw) aren't really adequate (wall is too thin and aluminium is a soft metal) - you will find that they will be easily stripped when you apply pressure on the set screws.
David