I guess that there is a spherical depression in the top of the actual secondary holder that the centre bolt mates with? Any idea of the gap between the top and bottom sections?
I've got this shot of it from another angle but it tends not to shed any light on its construction...
The threaded nylon rod passes through the spider hub and threads into the secondary holder, so the 3 cap screws threaded through the hub can bear against back of the holder. The gap would be a few mm, as all thats required is enough clearance for some adjustment tilt of the sec holder.
The threaded nylon rod passes through the spider hub and threads into the secondary holder, so the 3 cap screws threaded through the hub can bear against back of the holder. The gap would be a few mm, as all thats required is enough clearance for some adjustment tilt of the sec holder.
Mark - so that main threaded rod flexes to a degree, right?
Mark - so that main threaded rod flexes to a degree, right?
Yep, and in the process makes adjusting the tilt via the three knobs a joy, as they are always essentially `spring-loaded'. This is the secret to success behind the Protostar spiders.
Yep, and in the process makes adjusting the tilt via the three knobs a joy, as they are always essentially `spring-loaded'. This is the secret to success behind the Protostar spiders.
Interesting idea, I haven't liked my secondary collimation mechanism and want to get into it to see how I can improve it. But why delrin, Chris, wouldn't that be too rigid?
I think that it depends on the gauge of the rod Eric. I've used delrin in many projects in the past and have always found that it machines better than nylon. Nylon would be absolutely fine here, don't get me wrong.
No the rod is just Nylon, most big hardwares sell Nylon bolts .
The Hub is actually some kind of dense polypropylene..I said Delrin because I could spell it easier, but in hindsite wasn't a good idea
I think Cut to Size plastics in Chatswood can sell an offcut of suitable plastics , but I don't see any reason why the hexaganol hub couldn't justt be lamination of 2X 12mm ply ?
- I'll build my own then. 
