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DICKEYBIRD
10-13-2007, 08:44 AM
I watched the film “Fracture” with my wife last night and really enjoyed it. Sir Anthony Hopkins usually doesn’t get involved in doggy flix and this murder/courtroom drama was no exception.

The thing that kept me awake was the pair of gravity operated brass & walnut conversation pieces/mobiles/objet d’arts that were a prominent part of the movie. Sir A was a Mech. Engineer and had one in his office and one at home. They were Rube Goldberg’ish (Heath Robinson’ish to you Brits) devices that had long, complex tracks made of brass rod and a wood flywheel/ferris wheel device that turned. He would place large glass marbles at the top and they would roll down the rails, ‘round & ‘round, up & down then plop into the wheel for a slow ride around before dropping back onto the rail for more rolling action. The one he had in his swanky home was BIG, probably 6 feet wide and 4 feet high. I was fascinated by the motion and kept thinking about ways to make one myself out of brazing rod and scraps I have lying around. Just what I need, another project. With all the intricate brass parts, I reckon keeping the darn thing polished would be a chore, though!

I wonder if Sir A is a closet mechanical tinkerer? This movie and of course “The World’s Fastest Indian” both had some pretty nifty hardware prominently displayed.

Randolph
10-13-2007, 10:11 AM
I haven't seen the movie you are referring to but I have seen some of the "very busy doing nothing" devices you are talking about. I would love to have plans for something of the sort. The most fascinating one I ever saw was one in which one poured a small amount of water at the top. When the water reached a certain weight it tilted and spilled into a lower level and it filled and tilted, etc. In terms of doing useful work it had no value but it was fascinating to watch.
Does anyone here know where to find plans for devices of this sort? I have an odd number of projects going on right now and I like to keep them even.

A.K. Boomer
10-13-2007, 10:50 AM
I think what fascinates many people is the constant tripping of new pathways that introduce a new spin on it, when you witness one in action its a marval for sure --- their is a type of domino effect and because it goes at a certain speed can make it look harder than it really is to create,

One of the Tricks when building these type of things is to build from the last operation on up, or at least incorperate it into the overall plan, esp. when using a constant metering device like gravity and a specified weight --- you have to be "gravity stingy" with everything, but you can also "cheat" and have re-loading segments to where something may indeed reach the bottom of its run only to trip off something much heavier and higher up,,,

Mcgyver
10-13-2007, 10:57 AM
kenetic sculpture or rolling ball machines i believe is what they're called. quick google suggests it might be lucrative if you're good....or at least thats what the asking prices suggest...don't know how many they actually sell.

Evan
10-13-2007, 11:12 AM
Here ya go.

http://vts.bc.ca/pics3/brain.gif

Forrest Addy
10-13-2007, 11:22 AM
Years ago when a callow apprentice graduate I worked in the gear section. While the calciulations were complex and the work exacting there were long cuts to stand by when time hung a bit heavy for Ralph Fuchs and I. We needed some distraction that let us do our job.

There were plenty of hard parallel and benches and steel balls around and we got to experimenting. In time we cooked up a complex course where a rolling ball dropped, bounced off a piece of hard steel through the hole in a washer at the peak of its trajectory, bounced again at the peak of which to strike... etc for a dozen events to strike the tip of a spoon launching a little plastic clown into a nearby coffee cup whicch was the payoff.

It was silly but fascinating and the qualty of the rebounding surfaces depended greatly on their elasticity and the mass backing them up. A drop of kerosene wicked under a piece of 1 1/4" square HSS where it rested on a massy block of mild steel had a profound effect on a bouncing ball's rebound energy. It was a lesson in physics if you cared to look at it that way but of course anything that wasn't official productive effort was instantaly scotched by the management - but not before they played with it.

Elaborate mechanical contrivances are always interesting. I don't see millionaire railroad buffs rescuing old diesel locos from the boneyard, only hissing clanking monstrosities with tons of elaborate external linkage converting the thrust of mighy steam cylinders to rolling motion. US humans like visual commotion. It's eye candy to us. Steam turbines and induction motors might be efficient but they are boring after the first minute. They just sit there and run. But an elaborate pendulum clock, a mechanized science exhibit, or a choo-choo train switching cars in a freight yard will engage us for hours.

Go figure.

A.K. Boomer
10-13-2007, 12:05 PM
A drop of kerosene wicked under a piece of 1 1/4" square HSS where it rested on a massy block of mild steel had a profound effect on a bouncing ball's rebound energy..



It makes you wonder what the energy transfer of ceramics would be like, i think back to when all those people had those rows of ball bearings on the string sitting on thier desks and how efficient they were at transmitting power back to each other, How long would ceramics go in compairison?

couple things to consider; their not as heavy so even though more efficient at power transfer their will be more of a noticable penalty effect in air drag, maybe ceramic with a lead core would be the ticket, or put them in a vacuum and fill the last one's with steel so you can get the rack started with a magnet...

You can get ceramic bearings for your bicycle , there is an outfit out of boulder colo. (Excel sports) that sends me sales magazines all the time,,,

Here's some specs that the HSM's will enjoy;

"enduro ceramic bearing kits", made from pure silicon nitride material with extreme high density from uniform compaction (3.25 g/cm3) the micro-structual development of this material during manufacture is second to none. These high precision grade 5 SI3N4 pure ceramic balls are 5/1,000,000" from exactly round in sphericity, 60% lighter weight, and 7 times harder than steel, friction is reduced to near zero, Resistance to heat is 8 times greater (yeah - i need that on my bike!) while there is no comparison to corrosion resistance...