The Barber's Chair

Origins

Built for the Mountain Vista Railroad as a joke, this silly project came out better than expected. The mechanism required to make such tiny, subtle movements is by comparison enormous and complex, but it was fun to build. The basis of the mechanism is the old tried-and-true cam with a windshield wiper control.

The above image is shown upside-down for clarity—at least as much as practical given how cramped things were under this building. The motor rotates the cam until one of the two index pins hits the index switch, which stops it. Note the pins are not equidistant; this is because the chair slowly rises in increments, just as would happen in real life as the barber pumps the pedal, and lowers in one quick shot. The follower is connected to the lifter (seen here with nothing to lift, since it's upside down). The video makes things somewhat clearer:

Taking a Joke to Absurd Extremes

The barber's chair has since been relocated to the Laundromat/Barber Shop on the Men At Work diorama, where the effect has been enhanced to the point of ridiculousness. Once installed, I figured, hey, I can make the chair rotate. And once I did that, I figured, hey, I can also make it recline. This, however, required the development of a laughably complicated mechanism (some parts simplified, rearranged and/or omitted for clarity):

1. barber chair
2. recliner actuator rod
3. recliner pivot
4. chair base
5. lift/rotation tube
6. lift/rotation gear
7. rotation pinion
8. rotation motor
9. lift actuator
10. lift motor
11. lift cam
12. recliner actuator rod
13. moving recliner lever
14. moving recliner lever pivot
15. recliner lever link
16. stationary recliner lever
17. stationary recliner lever pivot
18. recliner crank link
19. recliner crank
20. recliner motor

In order to raise/lower and rotate the chair, a single gear (6) is used to create both movements: it is raised and lowered by a specially-shaped rod (9) and it engages a long pinion gear (7) as it moves vertically via a cam (11). The reason for so many levers and links for the recliner action is that the chair can recline regardless of its vertical position; therefore, some of the parts (12-14) need to move together vertically with the chair, while others (16-18) need to remain stationary, since it would be quite impractical to move the recliner motor along with the chair. The link between the moving and stationary levers (15) allows the recline action to be independent of the raise/lower action. I provide all of these details not because I think anyone else would ever want to reproduce it, but to offer potential solutions to other animation challenges, where an object must move in multiple axes independent of one another.

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