650Views13Replies

Author Options:

Hello everyone! I was hoping someone here with better understanding of engineering or just a fresh take on the problem can help me out.
Im working on this art project where I have a metal ball, aproximatelly the size of a basket ball, and i wanted to make it rotate continuously on a stand, in a way that all sides of the ball were shown eventually.

I've thought about this 3 axis sytem where each axis would rotate in turns to keep the ball rolling in diferent directions. Basically its like the insides of an analog mouse where the ball would rotate the gears and give the input of the location of the pointer, except here the gears should rotate the ball.

I've been trying to build something close to that with some K'NEX and a simple rotation engine that came with it but im not getting nowhere. I thought of building the gears myself but im finding it hard to come up with a plan. What would the gears be shaped like? What size? what distance between them? Even with trial and error would take me forever @.@

Anyways, any input, ideas, comments apreciated, Thx!

Tags:

Discussions

Ok, just to give this post some conclusion and to possibly help others who might read this, im posting the solution i came up with. I got hold of these little cog like plastic pieces (not the most sturdy solution, i know) and they fit together perfectly so i used them to translate the rotation movement into all 3 axis in turns. I think the picture explains it better. The motor is placed underneath the left axis giving power to that cog, which in turn powers the second axis and the second powers the third.

Will this become an eventual Ible? :-)

Hum... I didn't make it with an Ible in mind so I don't really have photos of the whole process... but who knows, maybe I can make another version of it with an Ible in mind. Will think about it. ;)

Even sketches in the mean time with the working model displayed would be great :-)

If the ball happens to fit the requirements (heavy, smooth, waterproof, have you considered a Kugel ball type stand?

If you have photos of the ball itself or your attempts at the stand it might help people give you more useful advice. Not me because I'm half-asleep right now. :P

Nice! I didn't know about these!

Unfortunately it wouldnt work cause the ball is definately not waterproof :P
Its made of small plate sheets soldered together by spot welding and some of the plates are perforated cause there are going to be sound speakers inside. As soon as possible ill put some pics of the ball and (failed) atempts.

Thx for the input tho!

I guess you wouldn't want to have an external structure around the sphere like the rings of the gimbal type mount around a globe.

Maybe do the same thing like the Kugel ball but use ball bearings - free rolling casters or balls in a socket, ball rollers in the cuplike base. The entire base would rotate to turn the sphere. But additional mouse-like internal drive rollers or wheels give you the x-y movement. Did you need to determine the position of the ball or require it to give you feedback on it's position? That might get a little complicated. Good luck.

Hi. I like the idea of using ball bearings, i'm not sure i understand what you mean with the mouse like internal drive rollers tho.

Maybe a fusion between the Kugel ball and the ball bearings, where the water would sustain the bearings but never touch the ball. I still don't see what would make it rotate tho.

Food for thought, thx!

Don't use water unless you want to turn it into a water sculpture. Use these roller ball supports.

If you turned your old ball mouse upside down and look at it, you see two rollers that ride up against the ball.  If you attach motors to them, they would spin the ball in the direction you wanted.  But then you might need an arduino to to the stepper movements to control the motors independently or manually pulse them with a joystick control.  You have to create the drive mechanism once you have the sphere freely supported in order to move.

Oh I see! I had thought of using rollers but I hadnt thought of having them controled by an arduino (and i actually have one!), I can see that working.

For some obscure reason I'm having trouble posting pictures here but I'll just add that the finished thing, with speakers inside and all will total about 5kg max i think.

Any advice on what kind of motors would be able to handle that sort of weight?

Thank you!

Weight shouldn't be much of an issue, especially if you run the motor shafts through bearings to take the load (rather than putting all the load inside the motor). It's going to be more of an inertia thing... If you get some hefty (read:expensive) motors designed to run a Bridgeport mill, you'll be more limited by the grip on the surface of the ball. A paper feed motor out of an old printer will probably work (free!) but you won't be able to quickly change the direction or speed of movement.

Thought: Mecanum wheels?

Why not float the ball?

http://www.ecvv.com/product/982020.html

That's the Kugel ball I mentioned, which apparently. (Foiled again!) It does bring to mind something else, though.

GMTA!