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My Next Project

 
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Squeaky



Joined: 16 Jan 2008
Posts: 45
Location: Derbyshire, England

PostPosted: Sat Jan 19, 2008 10:54 am    Post subject: My Next Project Reply with quote



I wish to construct a model similar to this ... but twisted into a sort of figure of eight.

Similar to the image of a rubber 'O' ring



What I really need, before I can start, is a net of the model that I can fully study. I would really like to make a cardboard model first

Constructing the basic torus, as shown above, was very interesting and, surprisingly, not very difficult. It is hollow and constructed fom five or six different hardwoods.

If anybody is interested I can briefly describe my method of construction.

Squeaky
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Squeaky



Joined: 16 Jan 2008
Posts: 45
Location: Derbyshire, England

PostPosted: Mon Jan 21, 2008 1:33 pm    Post subject: Reply with quote

The two following photographs show the method of construction for the torus.

Segments are assembled to form the ten sided section of rod. These were turned on a lathe to produce the shape as shown below.



When several of these assembled segments were completed they were sliced in ten degree sections and 36 of them assembled to form the torus as shown in my original posting




MY QUESTION .... for the more mathematically blessed

WHAT SHAPE WILL BE PRODUCED
IF I ROTATE EACH 10 degree SLICE/SECTION SAY 2.5 degrees.
WHEN ASSEMBLING?

If I keep everything aligned (NO ROTATION) then I produce a torus.

Squeaky
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robertw
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Joined: 10 Jan 2008
Posts: 394
Location: Melbourne, Australia

PostPosted: Sat Jan 26, 2008 3:28 am    Post subject: Reply with quote

Squeaky wrote:
WHAT SHAPE WILL BE PRODUCED
IF I ROTATE EACH 10 degree SLICE/SECTION SAY 2.5 degrees.
WHEN ASSEMBLING?

If I keep everything aligned (NO ROTATION) then I produce a torus.


A helix?

Rob.
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Squeaky



Joined: 16 Jan 2008
Posts: 45
Location: Derbyshire, England

PostPosted: Sat Jan 26, 2008 5:40 pm    Post subject: Helix Reply with quote

Does any member of the forum know of a software that I can use to investigate a helix?

Squeaky
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robertw
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Joined: 10 Jan 2008
Posts: 394
Location: Melbourne, Australia

PostPosted: Sun Jan 27, 2008 4:35 am    Post subject: Reply with quote

Not sure, but Stella can take an .OFF file as input, so if you have any programming skills, you may be able to write a program to output a helix in OFF format.

See http://www.software3d.com/StellaManual.php?prod=stella4D#import and http://www.geomview.org/docs/html/geomview_41.html

Something occurred to me though. You are slicing a cylinder of wood at an angle, so the cross-section is an elipse. There are only two angles where two such pieces will align: the original way that just recreates the cylinder, and rotated 180 degrees to create the torus. Any other angle will not line up properly.

A helix by the way is like one of the two strands in DNA, so it's not a closed shape anyway, ie not like the shape you made with the rubber 'O' ring.

Rob.
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Squeaky



Joined: 16 Jan 2008
Posts: 45
Location: Derbyshire, England

PostPosted: Sun Jan 27, 2008 7:30 am    Post subject: Helix Reply with quote

Thanks for the information ... food for thought!

I had wondered about the angle generating an elipital shape but thought that because I am only wishing to rotate a few degrees then a little judicious sanding may be all that is required to blend.

I am doing trials with some Teak ... will post a few pictures next week to show progress.

Squeaky
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Squeaky



Joined: 16 Jan 2008
Posts: 45
Location: Derbyshire, England

PostPosted: Mon Jan 28, 2008 7:03 pm    Post subject: What is the name? Reply with quote



What is the name of a shape with the configuration of the rubber 'O' ring above?

Squeaky
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robertw
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Joined: 10 Jan 2008
Posts: 394
Location: Melbourne, Australia

PostPosted: Tue Jan 29, 2008 5:01 am    Post subject: Reply with quote

I don't know what to call that shape. It reminds me of a Moebius strip, but obviously isn't. It's really a torus with a lateral wave through it. I'll ask around, but maybe it has no name.

Rob.
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Squeaky



Joined: 16 Jan 2008
Posts: 45
Location: Derbyshire, England

PostPosted: Tue Jan 29, 2008 7:25 am    Post subject: Name of shape Reply with quote

Thanks Rob!
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Squeaky



Joined: 16 Jan 2008
Posts: 45
Location: Derbyshire, England

PostPosted: Thu Jan 31, 2008 6:30 pm    Post subject: Four Twisted Semicircular Rings Reply with quote

I have just produced a quick 'mock-up' of the sort of thing that I wish to build.

I turned two wood rings, then sawed each into two. and glued the four together with a slight twist to each component.

With a bit of luck I should be able to develop this into the sort of thing that I want.

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