IANAE, and I need a lil’ help with a design. Don’t ask where these ideas come from; I haven’t the foggiest idea. This isn’t for a class project or anything; just for myself (yes, I know, I’m nuts).
I’m trying to make a big (wall hanging) quincunx…and I’ve figured out how to build everything except for a way to get the balls (1/4"-ish ball bearings) from the reservoir at the bottom, up to the top, one at a time, with 2-3 seconds between balls.
The best idea I can think of would be a screw (like the ones the Egyptians used to get water up the riverbanks – don’t remember the name) driven by some low power Radio Shack motor turning the screw at a constant speed. Is this feasible? Anyone have a better idea? Oh yes, and quiet, easy to build and inexpensive are all other requirements.
Well, your resume cracked me up. (The board is loading slowly tonight!) Ms. Zambrano doesn’t need a personal assistant in Maui?
It’s called an Archimedes screw. Sure, it would work, but something heavy and round like an individual ball bearing wouldn’t LIFT as well as it might be PUSHED ALONG on a gentle slope. You need something to hold it in the tube and if it’s vertical it will roll out. If it had depressions for the ball to rest in it could work, but those would be a pain (read as “expensive”) to do.
What I would look into would be buckets on an endless belt. The reservoir has a neck that allows through only one ball at a time.
How about magnets glued to a belt. The bin at the bottom would be designed so the balls approach the bearings in single-file. And at the top, the track would have to come close enough to ‘scrape’ the balls off, while letting the magnets pass through.
Cheap and easy.
The hardest part, I think, would be finding the right magnet/ball combination so it only carries one ball at a time.
You might also be able to find a belt somewhat like a tank tracks with (I don’t know what you’d properly call 'em) mud-traction flaps that stick out. These “flaps” would be like the buckets referred to earlier, or like platforms for the balls to set on as they go up to the top.
As I recall, there used to be (and might well still be) some contraptions set up in Boston Airport which moved balls up and then let them go through all kinds of ramps and so on. I remeber going there and seeing these things, and hoping for flight delays as they were so cool to watch.
You might also try looking at the various woodworking catalogs, as they have all kinds of devices and parts. I’ve also seen books devoted to constructing these types of amusing devices like you’re doing.
Were that I was to attempt some form of a randomizer, after having fabricated “lifts” using bicycle chain and brazed on “lifting buckets” for the transport of 1 inch steel balls to the top of a tall network of two-rail ball paths, I would suggest checking out the wind-up motors and mechanisms from old Erector Sets, or the more current “stuff” that Lego offers under “Mindstorm”, and other labels.
Your “screw” could be fabricated, with effort, but the results you are looking for most likely require a bit more work than you imply.
Wind-up mechanisms might be your best shot, coupled with a “conveyor” type hoist.
you could also take some ideas from some of the current K’nex sets out there. They have some that use the before mentioned ‘bucket’ method, and some that seem to lift the ball. Loook around and see what different design ideas you might be able to implicate.
There are some good gear sets, motors, chain drives (your conveyor) from MECCANO. Do a search on the web for that name and you’ll find lots “o” stuff. I think the prices are better than Lego Mindstorm.
Get a salvaged leadscrew or a piece of acme threaded rod with a -4 (very coarse) thread pitch. Take a piece of PVC pipe with an inner diameter that is slightly larger than the screw’s O.D. and rip a slot through one side that is slightly larger than the diameter of the balls. With slot on top, this could carry the balls upwards at a fairly flat angle. You could get a steeper angle if you put a pipe around the whole thing, but that would hide the action.
Better yet, you could put the screw in a square groove cut vertically in the case with a piece of glass covering the front and have the balls run straight up to the top in the corners of the groove. The groove would have to be cut out of hardwood or metal and I’m sure that getting the entrance angle right and sizing the slot to the balls and screw would be a real bi… er, would be major issues. This type would probably look the best though.
I recommend a leadscrew or Acme rod because these tend to come in more coarse pitches. FWIW, Wholesale Tool lists Acme threaded rod in as coarse as a 1/4" pitch, but it gets pretty pricey and might bind if you used 1/4" steel balls. A leadscrew that uses 1/4" balls would be perfect, but it would be expensive too. If nothing else worked, you might ask a bearing supply for help.
It is indeed still there. I just saw it last Sunday. The same fellow built a similar and larger device that’s still in the Boston Museum of Science. He used two different ways to raise the balls. One is an Archimedes screw, as described above. He used this for the larger, not-quite-bowling-ball-sized ones. The smaller balls (real billiard balls) are raised on a conveyor chain that has wire “buckets”.
There ARE other ways to do this. A friend of mine from 'way back, who used to be a professor, built the most beautiful device for raising 1" steel balls to the top of his device (I don’t know if he ever finished the downhill part). It raised the balls by knocking them up “stairs”, one step at a time. I suppose you could also do a vertical “walking beam” to raise balls a step at a time. Heck, you can build and enclosed catapult and shoot them up there, like an automaqtic pinball machine.
How the heck do you knock balls up stairs?? Does the “stair” jump up forcing the ball to the next one? That seems like a timing nightmare.
The basic idea was to take a Nicely Treated Piece of Wood, and put evenly spaced nails/pegs all the way down, so that a ball released from the top would be “randomized” as it traveled, resulting in a bell curve at the bottom. Once the balls were gone, the bell curve would empty into a bottom reservoir and be recycled to the top, one at a time, to repeat the process. I was planning on framing the contraption and hanging it on a wall.
As yet, I haven’t figured out an easy way to get the balls from the bottom to the top (the OP of this thread), or how to automatically empty the filled “bell curve.” Right now, I’m thinking just a timer and a spring mechanism. Another worry is that the wood might not be terribly flat (although a pass through a planar should do the trick); I’m considering another piece of material (fiberglass?) instead.
FWIRA, it seems like The Screw seems like an undertaking that requires more precision that this amateur (at best) craftsman could muster with my very limited skills.
I do like the idea of a catapult; I’ll have to revisit the napkin that I scribbled plans on to see if that could work…
Actually, THIS is at the Boston Museum of Science, too. It’s really part of an IBM packaged exhibit called “Mathematica”, that you can find elsewhere in the country (like Cicago’s Museum of Science and Industry). One of the parts of the exhibit is a device exactly like the one you describe. Balls drop out of a hole in the top onto an arrangement of pegs. The balls can go one of two ways at each peg, so after several layers you have a binomial distribution that collects in the bins at the bottom. There’s a line painted on the glass of the bin that shows the height predicted by the binomial disribution, and the piles follow the line every time. It’s very impressive.
The MOS tried to duplicate th same process in a little exhibit on their own using ping pong balls instead of the hard marbles the IBM exhibit used. It didn’t work – ping pong balls bounce too much, so they aren’t limited to one of two choices every time they hit a peg – they can bounce four pegs over. So the distribution looked a lot more random.
Not at all. Here’s one way to do it (not the way my riend did) – make set of stairs, with a sort of hollow in each dso the marble doesn’t roll back or off the side. There’s a set of slots cut in the center of each stair, and up through his comes a piece of metal that pushes the ball up o the next step.
Well, if you don’t mind it not being quite so visually impressive:
I’d think a basic bike chain at about a 15-degree angle from the vertical slanting upwards would accomplish this fairly simply. The balls should fit into the little hollows between link connections pretty neatly.
Then, it’s just a matter of finding a drive speed slow enough that the balls will be able to settle into the hollows as necessary.
Obviously, you’d have to have the balls approach this mechanism one at a time…