Raising marbles, using gravity

[Ian down london way]

This is a spin off of another thread: wip-cogitation-designed-by-clayton-boyer-t65479-30.html (see page three, near the bottom).

How many significantly different ways can you think of to raise a marble to the top of a kinectic sculpture (such as the marble chest here: http://www.foreststreetdesigns.com/Marb ... _Plan.html ) so as to keep it working, using only the power of a slowly falling weight (like a grand father clock).

The targets are to raise marbles through 60cm, releasing one every 3 to 5 seconds. The design should operate for around 30 minutes on one drop of a weight - say, up to 3kg, dropping through 1.5 meters.

One conceptual design per post, and try to keep repeats down.
Describe in words as best you can, and if you want to post a sketch too, go for it !

Fame and glory for the best - as judged by me (whether or not it aligns to the one I progressed the most).

(I came up with 7 on paper, and prototyped most of them)

Happy designing !

 

[Ian down london way]

Looks like I may have scared people off. Sorry about that. I hoped people would come up with some ideas I didn't think of.

Anyway, to kick it off - here is my Mark 5 design - An Archimedes screw.

So the idea is to have a shaft which is rotating at one revolution ever 3 seconds. A spiral of 'track' / trough winds its way up from the bottom, where a channel feeds marbles in, to the top of the shaft, where they drop out into an exit channel.

The spiral need not be circular, as long as the marble is picked up at the bottom, one could make it out of straight lengths of channelling, e.g. a triangle. The marbles would stay still till the shaft had rotated some 120 degrees then run into the next length.

Each section may hold no/one or two marbles, it doesn't matter, as long as they are raised though some height.

Tricky bit is that I don't think you can slope this at much more than 30 degrees. So to raise the required distance one would need a long spiral (although you could make it multi-stage.

If the 'spirals' were straight sided, but offset from each other in rotation, then the marbles would move in a rippling motion, which could look attractive, and sound even better.

 

[Jamesc]

My First Idea is a chain lift of contunuos buckets, much like the water lifters.

James

 

[Jamesc]

My second idea I thought was my own but a few seconds Googling turns this up which explains my idea so much better than words.

http://www.youtube.com/watch?feature=pl ... hQTr073SbA

I will keep racking my brain but to be honest keep clicking on the suggested links in Toutube seems to be covering all the ideas I have had so far.

James

 

[Ian down london way]

Well dang - that's an elegant design.

Most of my problems with this came from the friction which was incredibly difficult to avoid with some of the designs, which made them impractical with such a small power source.

I think for a weight driven solution, where I have very little torque available, one would have to eliminate entirely the friction between the rising and falling strips, but its the principle that is interesting.

I did have one which was similar conceptually. (My Mk 7 design) which had two strips, side by side, but angled slightly to a shallow V, each with ratchet slips cut on them, which would hold a mable. the motion was to slide them up and down past each other, and the marble would slide from one to the other moving up a ratchet step each time. I didn't get that to work, but the priciple meant that if the slope was gentle, it could move quite slowly, and so not require a high energy rate to operate.

The marble pump (http://www.youtube.com/watch?feature=fv ... 72lECvplzg) , for example, requires the wheel to lift many marbles, albe it short distance. requiring intemittent torque (most during the lift). Not sure that would work well.

Interesting though.

Cheers

(and thanks for replying)

 

[Jamesc]

Hi Ian,

Another thought - you have got me going now is a simple wheel. If you made it a little over 60cm in diameter you could have a single hoel on it to collect one marble at a time and swing it round to the top position. Careful weigthing oposite the hole would almost eliminate any lifting load so that all you would have to overcome was friction, whith gearing this should be easily acievable and this would increase the torque.

Probably not the most interesting of sulutions but definately on the KISS principle.

I too looked at the marble pump and had my doubts, the system has to lift the entire weight of the column of marbles at each stroke which for your low energy system would probably be a problem. I can also see potential for jamming in the sliding mechanism.

James

 

[samharber]

I'd go with the archimedes screw design, only set it vertically. You'd need a stopper inserted into the screw to stop the marble running back that can rise with the marble, which becomes the tricky bit. I'd probably use a conveyor belt (with stopper blocks attached to it) geared from the falling weight so that it moves independently of the screw, but at the same vertical rate (to reduce friction issues).

 

[Ian down london way]

Cool !!

The wheel was my Mark 2, prototype worked fine. I've made an elegant version, so the asthetics are ok. Still got problems with it though, perhaps more on that later, if people are interested (perhaps a different project thread altogether).

On the virtical screw idea, that was my mark 8. I tried to make it using fingers rather than solid screw, and so could either a fixed column of fingerrs from outside the screw, pointing towards the centre (does this make sence) so as the screw rotated, the marble was caught in an alevating V shape of fingers.

To make it work, the fingers would need to have sliping sides. In practice I found it very hard to prototype, with too much fouling. Maybe had I machined it, rather than cut everything by hand it would have been better. Not sure about the inhernat in-efficiecy.

My Mark 1 - in case you were wondering, was a large while, with concentric spirals on its face, picking up a marble form the bottom, and spitting them out of near the centre of the wheel. One practical problem was I'd need a 1.2m wheel, as the lift from from the bottom to the middle at best.
I amended it someone, and managed to get the hole higher up, using a different shaped channel, and it did have the merrit of looking interesting, as a number of marbles would be slowly converging at the some time. Could be made with a skeleton wheel face.