My mate over in California built one of these Lunar loops he used to take it down to the beech in Carlsbad great to watch, all those lovely scantly clad well taned girls wanting a shot could not ubnderstand why he wanted to do that all day!!!
It's not a difficult machine to build...apart from the steel hoops and I got those made 'professionally' (even though one snapped!!).
I used heavy duty plummer block bearings and they were OK but I could have used heavier ones as I never realised just how fast kids wanted to spin!!
The only problem I had was with getting the balance with someone in the chair...it had to stay level. I used a very large lead weight mounted under the seat and it worked perfectly.
One of my tricks when making (copying) things is to take rough measurements from photos...I'll post some more if you like....if I can find them.
Thanks mate, I describe something similar to a mate that wanted to make one, but I was thinking more of really hefty ball bearings. My idea was to have all the hoops made in 90 deg sections and just weld them together with the bearing fittings inbetween, but having the whole hoop made professionally would probably be better... Do you have any bigger pictures of it making my "stealing" easier?