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 Post subject: Barbell Cube by OSKARPosted: Sat May 07, 2011 4:43 am

Joined: Mon Nov 30, 2009 1:03 pm
Hi Twisty Puzzles fans,

Barbell Cube is a challenge for intellectual weight lifters. This puzzle has two Rubik's Cubes that are connected through an intricate gear system. If you turn a face on one cube, a face at the other cube will follow. However, the connections between the two cubes have no symmetry. This makes solving this puzzle extremely difficult. Let's say Rubik's Cube squared. Unfortunately, the prototype has failed.

A lot of work has gone into the design of the gear train. The connecting rod has seven layers in total. The inner layer connects the two spherical cores. The outer layer connects the two opposite white faces of the two cubes. The other five layers have gears to connect specific faces. For logistical reasons, I dyed the five sets of gears red, orange, yellow, green and blue, matching with the colors of the faces. This way, I could keep track which gear drives which face.

The gears are so-called "double chevron gears", as invented by car maker Andre Citroën. This gear design has the advantage that the gears do not slip sideways and that they can handle a lot of force. They also generate less noise than regular spur gears because of their continuous meshing.

The gear trains work really well. They never jam or touch adjacent gears.

The big problem of the prototype is friction. It is well known that 3D-printed nylon creates much more friction than e.g. mass-produced injection-molded ABS. In this prototype the friction is too much. At each face, the center pieces is connected to a gear with a square pin-hole connection. If I force a rotation, then the square hole in the gear deforms and the connection is lost.

There are two direction in which these problems could be approached.
1) The gear train could be made of 3D-printed steel.
2) The Rubik's Cubes could be made of 3D-printed polished nylon SLS.
The steel would result in a much stronger gear train. The polished nylon SLS is a technology that Shapeways is working on, based on their White Strong and Flexible material, that should have very smooth surfaces. There is a lot of cost involved in this, so I am opening this project up for sponsors. Please contact me if you are willing and able to risk to \$2000 for the potential to own the first working prototype of this design.

See the puzzle in my Shapeways Shop.
Read more at the Shapeways Forum.
Check out the photos below.

Enjoy!

Oskar
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Last edited by Oskar on Sat May 07, 2011 5:56 am, edited 1 time in total.

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 Post subject: Re: Barbell Cube by OSKARPosted: Sat May 07, 2011 4:54 am

Joined: Thu Sep 24, 2009 12:21 pm
Location: Chichester, England
Nice concept Oskar, although it's a shame it didn't work. The gearing mechanism looks extremely complex however, and I must complement you with the ingenious mechanism. Though this puzzle didn't work, don't get disheartened.

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 Post subject: Re: Barbell Cube by OSKARPosted: Sat May 07, 2011 5:40 am

Joined: Sun Mar 15, 2009 12:00 am
Location: Jarrow, England
My god Oskar, can your puzzles get any more complicated? Just because some suggests an idea, you don't have to go and make it I suggest a network of 500 different twisty puzzles across the whole world which are interconnected by quantum entanglement so that when one turns a random number of the others do as well.

BTW, a small typo in your post, the name is Citroën.

Oh yes, great idea. And don't forget to read my signature

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 Post subject: Re: Barbell Cube by OSKARPosted: Sat May 07, 2011 5:51 am

Joined: Thu Apr 28, 2011 3:43 am
Quote:
My god Oskar, can your puzzles get any more complicated?

That's I think, less complicated than the 17x17 at least.

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I thought a Fisher's cube were for fishermen, instead of a cube named after its inventor.

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 Post subject: Re: Barbell Cube by OSKARPosted: Sat May 07, 2011 7:14 am

Joined: Tue Aug 11, 2009 3:59 pm
Location: NJ
This is great idea, but it's a shame it didn't work.

On a different note, how much does it weigh?

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Oskar wrote:
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But that is only 2 kinds of people what is the 3rd?

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 Post subject: Re: Barbell Cube by OSKARPosted: Sat May 07, 2011 7:36 am

Joined: Fri Nov 04, 2005 12:31 am
Location: Greece, Australia, Thailand, India, Singapore.
We need a more robust method to make this work:

Five minute warm up spin (30km/h) on the exercise bike.
Ten sets of 20 sit-ups.
Use the Barbell Cube and do 25 repeats (alternating side, front, and overhead).
Half an hour swimming to tone, relax and line the muscles.

Optional: Five sets of 10 pull-ups.

*Then* this puzzle will work 100%, guaranteed!

Pantazis

PS. On a serious note, this structure is building now a connection
between puzzle designers and... magicians!

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 Post subject: Re: Barbell Cube by OSKARPosted: Sat May 07, 2011 8:16 am

Joined: Tue Feb 08, 2011 3:17 am
Location: Australia
That shaft is longer than it needs to be (all adds friction), does it need to be so long? Also maybe thin metal bearings inside the shafts to create a thin gap and reduce friction?

Yes, the material is too rough: if the cubies were a light smooth material like the GuHong it would turn the second one easily, but the problem might be the first one buckling then.

Good luck with this,
Burgo.

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 Post subject: Re: Barbell Cube by OSKARPosted: Sat May 07, 2011 8:24 am

Joined: Mon Nov 30, 2009 1:03 pm
Burgo wrote:
That shaft is longer than it needs to be (all adds friction), does it need to be so long?
The friction is in the cubes, not the gear train or shaft.
Burgo wrote:
At each side, there are four gears in a circuit. So per color there are eight gears.

Oskar

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 Post subject: Re: Barbell Cube by OSKARPosted: Sat May 07, 2011 8:31 am

Joined: Tue Jul 27, 2010 10:17 am
Location: Missourica
Awesome! Strange how one cube works, but the other one is unable to affect the first.

I hope you can find a way to overcome the friction, and I am VERY excited to hear about POLISHED WSF! That will open the door for many new concepts, if it can keep the precision of normal WSF

Good luck with the next prototype, I hope you can find a sponsor...

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Past project: The Geode
Current Project: Replica RPK-74
Future Project: Possibly another master mental
Oskar wrote:
I am now adding dummy cubes to my models to cross the 10% density threshold and save myself money big time.

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 Post subject: Re: Barbell Cube by OSKARPosted: Sat May 07, 2011 8:59 am

Joined: Mon Jun 30, 2008 8:38 pm
Location: Russia
Masterpiece!!!

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 Post subject: Re: Barbell Cube by OSKARPosted: Sun May 08, 2011 1:35 am

Joined: Mon Aug 02, 2004 7:03 am
Location: Koblenz, Germany
Sadly in the database there already is a puzzle called Barbell Cube.
When the time comes I will solve this by calling it as "Oskars Barbell Cube"

Anyway: Awesome concept.

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 Post subject: Re: Barbell Cube by OSKARPosted: Sun May 08, 2011 4:02 am

Joined: Fri Nov 04, 2005 12:31 am
Location: Greece, Australia, Thailand, India, Singapore.
I just realised that this Barbell Cube could be the basis for this evil puzzle proposed back in 2005.
The question is whether an external mechanism could be more efficient (in terms of friction)
than an internal.

Attachment:

cube_metrick.gif [ 52.34 KiB | Viewed 2559 times ]

Pantazis

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 Post subject: Re: Barbell Cube by OSKARPosted: Sun May 08, 2011 4:27 am

Joined: Fri Feb 08, 2008 1:47 am
Location: near Utrecht, Netherlands
Have you tried lubricating the mechanisms? A little silicone oil or grease might help solve these friction problems.

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 Post subject: Re: Barbell Cube by OSKARPosted: Sun May 08, 2011 4:52 am

Joined: Thu Apr 28, 2011 3:43 am
TomZ wrote:
Have you tried lubricating the mechanisms? A little silicone oil or grease might help solve these friction problems.

I dont think so. The 3d printed parts have texture on them and as you see after he lubed the 17x17, it did not improve it a lot (my opinion) He might need to use molds(I dont know) but I doubt it would work.

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I thought a Fisher's cube were for fishermen, instead of a cube named after its inventor.

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 Post subject: Re: Barbell Cube by OSKARPosted: Sun May 08, 2011 5:26 am

Joined: Sun Mar 15, 2009 12:00 am
Location: Jarrow, England
On my puzzles using WSF, I have sanded, primed, sanded and then and spray painted them using gloss black, which results in a nice shiny finish. I don't know how well the paint would stand up to the rubbing, but if you wanted to see if you could make the prototype work, then maybe this is a possibility.

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My Shapeways Shop: http://www.shapeways.com/shops/gus_shop

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 Post subject: Re: Barbell Cube by OSKARPosted: Sun May 08, 2011 7:35 am

Joined: Thu Dec 02, 2004 12:09 pm
Location: Missouri
Oskar wrote:
The big problem of the prototype is friction. It is well known that 3D-printed nylon creates much more friction than e.g. mass-produced injection-molded ABS.

To me, this begs the questions... Is there a mass-produced injection-molded ABS 3x3x3 that you could adapt your mech to? Steal the corners and edges off of that and just print the other parts. There are so many different 3x3x3's out there I think there is a chance you might find something that would work.

This 3x3x3 has room for a ball core. It might work.

Just an idea,
Carl

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 Post subject: Re: Barbell Cube by OSKARPosted: Sun May 08, 2011 12:56 pm

Joined: Mon Mar 30, 2009 5:13 pm
I love it! I hope you will try again and get it to work...

Then you could try this same mechanism in my Molecube.

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If you want something you’ve never had, you’ve got to do something you’ve never done - Thomas Jefferson

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