Newtons Cradle Project

[onebadziggy]

Well if you arent familiar with what it is.. http://www.btinternet.com/~jean.darc...e/craddle.html

Thats what it is.

Here is the task- Make one much much larger than those that are made for novelty items. As in stick it in your front yard "hey look its art!" large. This is for my friends dad, so my neighbors wont be wondering about my intelligence. Just his.

What we need is the balls. We purchased a novelty one, and observed a few thigns-
1) This thing is a peice of crap because its not built close enough to perfect that it doesnt rock straight.
2) We need massively strong foundations for this. Sooo.. metal poles in concrete forms?
3) An adjustment system for where and how long the cables/strings are is needed for fine tuning.
4)The longer the strings are, the slower and longer the oscillation goes on.


So with that in mind,
1) Is this feasable?
2) Where do we get balls? Do they make 10" Ball Bearings?

Another consideration-
Could we make this thing musical at all? There are these chinese exercise balls that are completely enclosed, but chime. They work like a wind chime, as they have a ball rolling around inside and it hits the chimes. The intent of the ball is to roll it around without making a noise. or should we just attach a bell to the bottom of each ball?

I'm sure I have more considerations for this project, as I have given it several days of thought. But, since we are all DIY's here, and our minds run rampid, I'm looking for ideas and mental support.

Thank you for all ideas!

[ststone]

I just got my self 10 IRF9610's with cut off fins ...
If they will do the job you can have them.
Rosey

[planet10]

Originally posted by onebadziggy
What we need is the balls

The 1st thing that came to mind was bowling balls, PVC pipe (perhaps filled with concrete), and picture hanging wire.

dave

[onebadziggy]

I just got my self 10 IRF9610's with cut off fins ...
If they will do the job you can have them.
Rosey

What are these? I'm sorry but I have no idea.

planet10, I'm intriged by your pvc/concrete idea. I might go with steel supports however, because I love welding and dont get to do it enough.

How much are bowling balls usually? I think they will take the force, but I will do some testing/dropping to see first.

[planet10]

Originally posted by onebadziggy
How much are bowling balls usually? I think they will take the force, but I will do some testing/dropping to see first.

I was thinking 2nd hand stores....

if you like welding then steel is the way to go.

dave

[Strike Shadow]

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[mrfeedback]

The balls need to be made of non lossy material.
Concrete and pvc would not be suitable.
Bowling balls ought to work well.

Eric.

[onebadziggy]

Well, I dont think we were going for concrete/pvc balls if thats what your saying. But, we are in the process of finding a bowling ball that we can test to see is it will hold up to the abuse. I'll have pics if we shatter it.

[Da5id4Vz]

I’m no expert on this (or any other subject for that matter) but I was under the impression that bowling balls tend to have cork cores. Perhaps this is just for the lighter kids balls, but I wouldn’t be surprised if after drilling it you find that it is not homogeneous.

I'm assuming your shopping at second hand stores. This could make it take some time to get 6 equal mass balls.

Have you considered using large old magnets (from 12” speakers?) aligned to repel like poles? It would be much quieter.

[BrianGT]

A long time ago, I saw one made out of old bowling balls that were thrown away from a bowling alley. It worked quite well for the purpose, but I couldn't personally see a reason to build one. Bowling balls can definately take the abuse, and even previously abused bowling balls will work for the task.

I would search second hand stores as dave mentioned.

--
Brian