How about a door stop - the little wedge you push under a door to keep
it open? To get the wedge out you often have to push the door a touch
more open to get it off the wedge and then the door can close. I have a
colleague who opens the door fully and then kicks the wedge in. It's
almost impossible to get the wedge out and close the door because it's
fully open.
Bob at PC
-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu
[mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Ricca,
Bernard P
Sent: Tuesday, March 17, 2009 7:44 AM
To: phys-l@carnot.physics.buffalo.edu
Subject: [Phys-l] Interesting Complex Machines - Wood That Works
----snip----
Does anyone know how such a mechanism may be put together to prevent
rotation in one direction (ie. clockwise), until a small amount of
opposite rotation is generated (ie. counterclockwise), that would allow
for the primary rotation to occur (ie. clockwise)? I love it when a
student has me stumped. :-) Any help would be greatly
appreciated...from both of us. (hahaha)
----snip----
In addition to the other suggestions that have been posted, I suggest
contacting the artist, David Roy (http://www.wordthatworks.com). His
undergrad degree is in physics, his escapement mechanisms are sometimes
quite interesting, and he might be willing to talk to you. I've seen 4
or 5 of his works live, and you should know that the "period" on some of
his sculptures are well over an hour, so the short YouTube videos won't
show the whole thing. (The "repetitions" aren't always exactly the same,
so the motion is actually chaotic.)
Barney
Bernard Ricca, Ph.D.
Assistant Professor
Graduate Program in Math, Science, and Technology Education Department
of Mathematical and Computing Sciences Saint John Fisher College 3690
East Avenue Rochester, NY 14618
585-899-3866 (Office)
585-899-3872 (FAX)
bricca@sjfc.edu