Revolute joint 3d printer

[pbedenbaugh]

I recently saw a Renishaw Equator, a tool changing delta robot shop floor CMM.
The kinematics are revolute delta, with scales on each axis. It was quite an impressive machine

I know that most delta printers use linear rails rather than revolute joints. What considerations have lead to this choice ?

Thank you.

[oliof]

@pbedenbaugh for consumer deltas, part count, build complexity, availability of parts. You can build a linear delta with rails and arms for less than 500$. I would guess a single actuator on the Equator costs an order of magnitude more.

[oliof]

I hasten to add that I think I saw a similar machine on the reprap forum years and years back, but search on that is terrible so I couldnt find that one.