Archimedes’ Screw

[Maurice Cox 1Participant @mauricecox1]

I though that perhaps some might like to see the Archimedes" screw that I made a couple of years ago. The screw itself is seven inches long, and two inches in diameter. The cost was minimal. The screw part is made from halves of "lolly" sticks, and the casing from coffee stirrers. It just needed a few simple jigs to get all the bits the same. Properly, the screw element should be sanded smooth rather than left stepped, but I left it like that to show the construction; and it looks nice! The lower end is copied from a picture of a full size one that I found on the internet. I suspect that it makes it less likely to get damaged. I added the brass lip to stop it dribbling when in use. In full size it would not be an issue. The tanks are base on a picture I saw of an early chemical works. Children love to try it out.

[Maurice Cox 1Participant @mauricecox1]

[Brian WoodParticipant @brianwood45127]

No wonder the kids enjoy it, it is a nice model to demonstrate the effect on

Brian

[Jeff DaymanParticipant @jeffdayman43397]

Great job Maurice, well done. JD

[Neil WyattModerator @neilwyatt]

I love the handle – it fits the style perfectly!

Neil

[Maurice Cox 1Participant @mauricecox1]

Thanks for the kind comments gents. I first made one from balsa wood when I was eleven, after being told about them at school. Always promised myself to make a better one. It took me long enough! I'm glad you like the handle Neil. You can find many examples of cranks of this shape on old machinery, from the pumps in "De Re Metalica", to treadle fretsaw machines and some textile machines, etc. I've often wondered if there was some perceived advantage to them, or was it just the appearance?

regards Maurice

[Michael GilliganParticipant @michaelgilligan61133]

Wonderful work, Maurice.

If you want to bring the Children up-to-date … show them that the same device, run the other way [i.e. as a driven instead of a driver] is being used in water powered electricity generation.

MichaelG.

.

Example

Edited By Michael Gilligan on 07/08/2015 20:37:29

[Neil WyattModerator @neilwyatt]

Posted by Maurice on 07/08/2015 19:44:44:

I've often wondered if there was some perceived advantage to them, or was it just the appearance?

This has had me puzzling too in the past, it seems to be common with cast iron handles, so perhaps it is less likely to snap if the handle is jarred?

Neil

[modeng2000Participant @modeng2000]

There is one driving a generator at Duncton Beam Pump near Petworth.

John

[Steve WithnellParticipant @stevewithnell34426]

Posted by Neil Wyatt on 07/08/2015 21:30:34:

Posted by Maurice on 07/08/2015 19:44:44:

I've often wondered if there was some perceived advantage to them, or was it just the appearance?

This has had me puzzling too in the past, it seems to be common with cast iron handles, so perhaps it is less likely to snap if the handle is jarred?

Neil

The other example of this is flywheels with curved spokes – whatever perceived advantage there is must be lost if it's turned the other way?

By the way Maurice lovely job! I've a little woodworking job on the bench at the minute, but with  malicious(ish) intent in mind . If it ever gets finished I'll post it.   Just need work to get out of the way for  while.

 

Steve

Edited By Steve Withnell on 08/08/2015 08:36:18

[Gas_mantle.Participant @gas_mantle]

Posted by Steve Withnell on 08/08/2015 08:34:58

The other example of this is flywheels with curved spokes – whatever perceived advantage there is must be lost if it's turned the other way?

Steve

A very nice model, good to see something a little more unusual.

As for the curved handles my guess is they would be used as a way of lessening the stresses if it's intended the rotation will be in one direction only.

I'd assume the handle in the model is a 'clockwise' handle as you look at from the front.

Peter.

[Gordon WParticipant @gordonw]

Cast flywheels and etc. were made with curved spokes to help cope with shrinkage in the casting process. Or so I was told, but sounds very reasonable.

[Ian S CParticipant @iansc]

Another reason for curved spokes(so I'm told) is to take the shock in a internal combustion engine.

Ian S C

[Maurice Cox 1Participant @mauricecox1]

Thanks for all the nice comments gents; yes Peter, the handle is 'clockwise'. One thing that is not visible in the photos is that the spindle, or axle, ends in a ball at the lower end. It just locates in a socket, and is not restrained along any particular axis. Thus there are no alignment problems, and it is readily unshipped went not in use, as were some of the full size ones. Probably to stop them getting nicked!

There is another irrigation device that would be an interesting model;' a dragons backbone"; a Chinese water elevating machine that is principally a chain of wooden plates moving in a close fitting trough. There are pictures on the internet. I regret that I have lost the web addresses. Worth searching for though!

Regards Maurice

[Ian S CParticipant @iansc]

There is an Archimedes screw pump at a farm just down the road from here. The main body is a bit of 100 mm plastic pipe, a bit over a metre long, the screw is driven by a little water wheel on the bottom end that sits in the water race, the elevated water goes into a trough made of a length of spouting, and waters the garden. Its been running for at least twenty years.

Ian S C

[KWILParticipant @kwil]

Loads of pictures for "dragon's backbone" just look

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