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DIY archimedes screw 4-5 feet long Answered

Hi.I'd like to build a garden marble run from the top of a 3 metre high wind spinner structure. But it would not be convenient to have to climb to the top every time to replace the marbles.Since it's a wind spinner, I could use the top drum to turn an Archimedes screw to lift the marbles back up. But how do I make the screw. It would have to be as light as possible, though the object need not be a marble as opposed to a table tennis ball, say. The screw would be 4 or 5 feet long from the top of the drum to the lowest wind spinner level. I enclose a video. Thanks. Cheers, Laurence

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l.peddle123456
l.peddle123456

11 months ago

Hi.I'd like to build a garden marble run from the top of a 3 metre high wind spinner structure. But it would not be convenient to have to climb to the top every time to replace the marbles.Since it's a wind spinner, I could use the top drum to turn an Archimedes screw to lift the marbles back up. But how do I make the screw. It would have to be as light as possible, though the object need not be a marble as opposed to a table tennis ball, say. The screw would be 4 or 5 feet long from the top of the drum to the lowest wind spinner level. I enclose a video. Thanks. Cheers, Laurence

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Jack A Lopez
Jack A Lopez

Reply 10 months ago

Hey. I think there might be something goofy going on with the way the Instructables machinery deals with video clips. Specifically, I can't see, or download, the videos you have attached to this topic. When I try to do this, I get this error telling me, "The page isn't directing properly."

You should try this yourself, or ask your friends to try this.

Also we might wonder why Instructables allowed you to upload that kind of file, if it is not going to share it with anyone.

By the way, I recall about a month ago, someone on this forum successfully shared a video clip using imgur. It was this topic:

https://www.instructables.com/community/How-to-fin...

To find it, in that topic, just use Ctrl-F to find the word "imgur"

There is also Youtube, I suppose. Although, I am reluctant to recommend one or the other, since I myself do not ever upload video, and I do not know the best ways to do this.

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Jack A Lopez
Jack A Lopez

10 months ago

In my previous reply, I wrote that helical screws could be built up from annular strips.

Some additional study has revealed to me, the shape of these strips only approximate the shape of a helicoid.

I mean, I derived the formula for the arc length of a helical spiral. Then I noticed the length of the spiral, on the inside edge of the screw, and length of the spiral on the outside edge of the screw... Those lengths do not have exactly the same ratio, as the inside and outside arcs on an annular strip.

As a consequence of this, the outside edge of the annular strip needs to be stretched a little bit, or the inside edge squished a little bit.

Also I found a document, a one page summary, titled "Development of Helical Screw Flights," on a page at slideshare-dot-net.

https://www.slideshare.net/VarindoMegatek1/spiral-...

It is just one page, so I might as well attach it, as a picture, to this post.

Actually, there might be a few of these type slideshows, on slideshare, including this one:

https://www.slideshare.net/Duraipandimech/helical-...

Also I found a video, of some people actually constructing a giant helical screw, out of annular strips, cut from circles of steel sheet... beating on it with hammers, and welding it, and the end result looked really nice.

spiral-flight-development-1-638.jpg
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Downunder35m
Downunder35m

11 months ago

I cheated something similar for a project some time ago.
We used copper pipe but never mind that ;)

We used a 50mm PCV pipe and created a tight pipe coil.
Then we used some wooden stuff to push the turns apart and to keep them at an even spacing.
The finished product was a snug fit into a 80mm PVC pipe....

Way too heavy but you could use a ligh carboard tube and these insulating foam tubes used for conrete slabs from your hardware store.
No clue if something square is available but it is not hard to make a hot wire cutter and a spacer to cut off a slice along the tube to get a flat surface for your ball.

If you use steel balls you could cheat with just a simple tube and a magnet that is mounted on a string and going endlessly over two pulleys either end of the pipe.
Magnet "grabs" the ball, lifts it up and once the distance is too great the ball drops to start the journey again
Just make sure the top end of the pipe has something to divert the ball to not drop back into the pipe ;)

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Jack A Lopez
Jack A Lopez

11 months ago

I think helical screws can be built up from "annular strips," where an annular strip is the shape you get by drawing two concentric circles, and then making at least one cut ( e.g. if you were making this with paper and scissors) to open up this ring-shaped thing, into a curvy strip shaped thing.

Pictures would help us understand this better.

I found a nice one, but so far I have not chased it back to its original context. I will attach it to this post.

Also I found that phrase, "annular strip" on this page:
http://pi.math.cornell.edu/~dwh/papers/EB-DG/EB-DG...

If the formula found there, for r, the smaller radius of the annular strip, seems confusing, it is because that formula has "p" in place of "pi" (You know, the well known constant, pi=3.14159...) and also that expression is equal to (1/r) instead of r.

Anyway, I re-wrote it as:
r=(H^2+(2*pi*R)^2)/(4*pi^2*R)

And when I feed that to Octave, using that author's same example numbers, R=1, H=10, I get the same answer he does.

>>> H=10,R=1,r=(H^2+(2*pi*R)^2)/(4*pi^2*R)
H = 10
R = 1
r = 3.5330

So, hopefully that is the right formula. I still do not know how it was derived, so I guess I am presenting it here, "without proof."
;-)

Also I found a video, that might have some clues, but I have not watched it yet. Here:


paper-helix-screw-marble-run.jpg