Joseph Gwinn wrote:
Bob Engelhardt wrote:

... those [original] hinges would be so much simpler to build.

Those original hinges looked hard to make, and I wondered if they would
tend to jam, especially if a little dirt got into them. Also, the
cylinder axes would need to be precisely colinear, or they will tear
each other apart. Virtual ball joints will not have this problem.

"Eye of the beholder", I guess.

Bottomley has a web site. I wonder if he will answer questions.

Good idea. I've asked on the Practical Machinist forum. If I don't get
an answer, I'll try Bottomly. Or you could.

Bob