Grim's idea

[Michael]

I was just wondering, Grim once boasted that he made a wheel that worked but the force was so strong it blew itself apart. Has anyone ever tried to duplicate his work or correct it so it didn't break apart?

Regards,

Michael

[Kirk]

I think he was having fun with you.

Kirk

[Jonathan]

I don't think so. This is the where those messages are: http://www.besslerwheel.com/wwwboard/me ... /2369.html

[Chris]

Hi Michael;
I built a verson of Grim's idea, but I think I diverted a little
too far from his design. The one I constructed used a aluminum "I"beam,
supported on ball bearings in the middle, to replace the wheel. At each end
of the "I"beam were roller bearings to attach the arms that Grim had problems with. And these arms are were I think I went wrong. I used old
connecting rods from a Ford V-8, filled the small end with lead and the big end with aluminum. The problem was weight distribution, the connecting rods were too heavy in the section between the small & big ends, so not
enough weight shifted during rotation to keep it running. Or at least I think
that was the problem. Have not had the time to replace the two rods, too
many house projects !
Chris

[jim_mich]

This looks like a quick easy wm2d project. So I threw it together. The little weights are 6 oz. But what are the big weights? The stop in one direction puts the arm in-line with the axle. How much rotation to the second stop? The spring location and strength would be very helpfull to know. And how heavy is the wheel on which everything is mounted?

Any proposed dimensions and weights would be helpful.

[Michael]

Grim had all the dimensions and how to posted up, somewhere at sometime. I think the springs were 1/16 input to output or something like that.

Reg.

Mike

[Fletcher]

FYI Jim - I think Grim & Smithy's "destructo" mech may have looked like this. I think I followed it thru pretty closely at the time but couldn't see how the mech was supposed to reset itself other than using spring assisted leverage (which had symmetry). Search by Smithy (he backs up Grims comments) as author as he only made a couple of posts from memory. I must have missed something in their descriptions.

RE : My Interpretation of their idea - The bottom positioned mech once the sim is run is pulled across to the stops by the spring & the kinetic force causes the wheel to rotate ACW but the spring had to be relatively weak to let it reset in any way.

Now if you could have the spring attachment on a sliding slot moved somehow (to change the angle of attack) so that it didn't go all the way around (180 degrees) b4 resetting, then that would be very interesting.

-Fletcher

[Michael]

It seemed a little unbelievable I know. Grim was questioned by a few people even myself and maintained that from a stop position it accelerated and had what Fletcher mentioned, about six rotations before it destroyed itself. If that is really true then this should be worked on. It is pretty clear why.

Regards,

Michael

[jim_mich]

Thanks Fletcher, I'll need to study that and see what I can come up with.

While messing with this I discovered something new. It might be a piece of the puzzle. If you construct a wheel like I'm posting here and if the pendulums swing hard enough to hit the stops then it transferes energy from the swing of the pendulums to rotation of the wheel. I thought I had a self runner tonight, but NOT. What I found interesting is I could set the wheel to spinning first at any speed and the wheel would speed up even more, then continue to turn at a steady speed (running with no friction).

The springs negate gravity allowing the pendulums to oscillate and if they oscillate hard enough to hit the stops they increase the wheel's speed until the excess energy is lost and they don't hit the stops anymore. Now if I can somehow figure out how to make them swing a little harder each turn?

[MrTim]

From my experience, any impact in the direction of, or opposite to, the wheel's rotation is just going to cause you trouble. The impact does set up oscillation, but of the wheel. And if all of the mechs in the wheel are not synchronised to impact at the same time, this will only compound the problem further.
It is better to expend the energy of impact radially (i.e. inward or outward from the axle.) Though the impact will not assist the wheel in turning, it also won't cause a fatal disruption in the wheel's movement....

[jim_mich]

Mr Tim, they ARE impacting radially! The rotational force comes from the centrifical force of the pendulums which have truncated swings. Think of a plain simple pendulum. If placed on a scale it would cause the scale to read higher and lower weights as the pendulum swings. The pendulum registers MORE during the the middle of the swing. If you put a stop at each end of the swing truncating the swing arc and bouncing the pendulum off the stops, then it will seem to weigh more. What I discovered is you can do this continually on a wheel, converting the swinging energy into rotational energy, while keeping everything symmetrical.

[Fletcher]

Interesting comments guys. I'll have to study them closer when I've more time. Helping to shift a mate & his family into their new house today.

Just an observation that occurred to me recently. Anyone else notice the keen similarity between Grims destructo mechs & Techstuf's latest design ? In essence they appear almost identical at least in ratio's & use of right angles etc. Maybe they're onto something after all ? ... hmmmm ... ?

-Fletcher

[Jonathan]

It's hard to tell from the attachment because I don't understand it (the yellow circles clearly move in and out over the course of a cycle, but what hols them from all hanging down to 6?), but it seems to me than the pendula impact when they pointed radially, which means the impulse felt by the wheel must be largely tangential.

[jim_mich]

Opps, I should have stated how the springs work! They are neutral when the pendulum is mid-way. They have tension when the pendulums reach the inner or the outer stops. It is the default mode for wm2d. The spring is stretched or compressed from the length you tell it for the spring.

[jim_mich]

Here is a graph of the speed up in rotation. Please note downward is faster! I was playing with the weight of the flywheel here to see if it effected it. The bottom line had a lighter flywheel. The rest had differing amounts of push to start, although the wheel would start by itself. The pendulums would oscillate quite fast while the wheel turns rather slowly.
But you can see where it speeds up then holds its speed.