Iris wheel

[jim_mich]

Jonathan, I bought some K'nex in an after Christmas sale. I must say they are somewhat flimsy, no where near as strong or rigid as the tinker toys or erector sets of my childhood. You should have seen the erector set we had, my brothers and I! It was about 3 or 4 sets combined into one. We could build just about anything our imagination could come up with. My oldest brother got the original first set somewhere in the 1940's.

[Jonathan]

Yes, I had an erector set, they are more sturdy but they take longer to build. K'nex is kind of like erector combined with lego, you can build anything and quickly, but it isn't strong. But I think the strength is quite good considering the meathod of construction, I've built many things that were so strong that I couldn't take them apart without a wrench, but they were small and dense.
I've done more fiddling and still can't get it to work. Gordon, I'd like to see some pictures of this device, I can't figure out what I'm doing wrong, I've tried at least 15 variations.

[Jonathan]

Well, I've done something stupid again. Apparently I misunderstood how very important the 2:1 ratio is and have come to the realization that probably all the variants of the device I've made didn't meet this criterion. So this means all my experiments are pretty much null and void.
Unfortunatly I'm busy for much of tomorrow, so I will be remaking it tomorrow evening and hope to report back with my findings then.

[grim]

Racer, just a suggestion, wouldn't alter the current setup you have too radically until you get it all debugged.

With the materials you described using you should be proud that you got it to want to run at all.

You are welcome to any help, info or experience available here.

Regards

grim

[jim_mich]

Jonathan (and others), here is how the ratio effects the outcome.

The arms act as levers transfering the gravity push at the top around to the bottom and redirecting the force upwards. Let these little o's and dashes represent the arms, but stretched out straight...

Code: Select all

           o---
         o---
       o---
     o---
   o---
 o---

Each arm, through leverage, acts like a long arm exerting its force at the point V.

Code: Select all

 V---------o---
 V-------o---
 V-----o---
 V---o---
 V-o---
 o---

Now if you extend the length of the arm to the fulcrum point, it is easy to see that much more push from the first weight gets transfered to the last bottom weight.

Code: Select all

 V---------o-------
 V-------o-------
 V-----o-------
 V---o-------
 V-o-------
 o-------

But note that the movement distance is reduced. How does all this comes together and effect the outcome? How much can it raise the bottom ball? Questions questions.

[grim]

Maybe Racer can get some lift measurements off his model so you can plug some more info in?

[Jonathan]

That isn't the ratio I was talking about jim. I meant the big radius at 3 o'clock divided by the small radius at 9.

[racer270]

Guys, I forgot to tell you I sand bagged the handle bar gooseneck area with 50 pounds to hold the wheel down to the bench. Also what I am witnessing is the pinch effect to be very desirable i.e., keeping the lowest most wieght as far right as possible this seems to take the jumpiness out of the wheel. I am thinking of increasing the overlap to approximately 50% so a recalculization of circumfrance vs. arced arm length would have to be reanalyzed in an effort to smooth out the rotation, the bottom weight still being tucked into the tight radius is beneficial prior to bottom dead center also Jonathan I think now that a less than 90 degree fall out on the right side would also increase a torque thrust angle. Now I would also like to suggest as addition of Grim's to launch the 2 oclock weight via a spring or a magnetic repulsion at a vectored angle would significantly aid in the rotational force. keeping this all in mind I think that the right to left side radius ratio should be increased to approximately 3 to 1. One more aspect, the recapturing of what I am going to call the 5 oclock postiton weight might require a roller tip because of the inherent drag I am seeing as the ball drags down the length of the radius arm. I think this is the direction my instincts are telling me to proceed with. As of yet the rotation of the wheel is jumpy and Jonathan suggested something spongy to catch the two oclock throw out weight would also be desirable stop the bounce via a spring shock, maybe, not too sure about this theory yet , but the bounce isn't a good thing. I am looking for suggestions collectively from everyone before I attempt a rebuild. Gordy

[racer270]

5 balls on the right side of the axes is = to 5oz. it will lift a 6oz. weight on the left side(ballenced/stop) when the pinch efect hold the 5o.c. ball to the right of center. ie; 9 inch radious. it does not let (bdc) flop down and keeps the ball from having to be lifted back into to the 9 inch radious, apx. 6oz. of lift at the 9 inch radious, left side. ( 8 weights total of 8oz.) i wont to lonch and then stop the bonce efect of the apx. (1o.c.+ location) weight next. i think a perment mag. in a mounted repulce at angle to aid in rotation could kick it up a notch ?

[Jonathan]

I didn't catch that. But what I did understand confused me, if the 6 o'clock ball shouldn't be lifted, then how do you manage to lift the 5 o'clock one?

[racer270]

try to lift the 6 and the 5, more right side weight, vea more overlap, its a+ to the rotational efert. adding weight to the right side!!! if it doesent drop it doesent have to lifted!! new overlap apx. 50% less work at (bdc).

[Joel Wright]

You might want to check out Bill McMurtys Maschine Tractate # 10 for some ideas that might help you with the Iris wheel.

[jim_mich]

This one looks very much like the Iris wheel

[grim]

That's true, but unlike JB Racer has managed to pick up the 6 oc plus the 5 oc. He's totally raised the bottom, eliminating the keel effect, which is what it takes.

When he works the bounces out of it, the closer to 12 oc he makes his outward throws to the right the faster it will go. And with the centrifugal force acting to equalize all weights at "X" speed. there's the governor. If he employs springs and repelling magnets to work the weights the spring
tension, and therefore the running speed, could be adjusted.

[grim]

For all you new agers: Edgar Cayce

http://all-ez.com/nofuel1.htm


For all you religious ones: Rev 9:1

"And the fifth angel sounded, and I saw a star fall from heaven unto the earth, and to him was given the key to the bottomless pit"