CLaNZeR can achieve overunity!

[gravityblock]

Also why does the roller have to be rotated 180 deg.?

Because the field from the Halbach and roller are still pointing in the same direction, thus the force will be in the same direction.  You either need to reverse the direction of the field on the Halbach, or need to reverse the direction of the field on the roller, which is rotating it 180 ^o.  If you pay attention to ClanZer's videos, then you will notice he rotates the roller in order for it to go in the other direction.

Here's two videos demonstrating this principal, http://www.youtube.com/watch?v=wvScSTbly1c  and http://www.youtube.com/watch?v=_-kQans2rww  Notice how the direction of force on the roller is according to the polarity of the current (reversing the field of the horseshoe magnet will also change the direction of force on the roller).  Reversing the polarity of the current is the same as rotating the roller 180^o (the roller stick has a magnet in it, which magnetizes the steel balls in a particular direction).

[Edit:]  The second video is using the concept of a homopolar motor, but the basic principal remains the same.

GB

[Rapadura]

So, it's just a matter of distance before the energy generated by the piezo film under the rolling surface can be enough to power an electro-mechanical arm that takes the roller at the end of the last pair of Halbach arrays, rotates the roller 180 degrees, and put it ar the right position to start rolling in the inverse direction, towards the beggining of the track, where there is another electro-mechanical arm.

Of course I'm assuming that the roller can travel through not only 2 or 3 pairs of Halbach arrays, but through 700 or 800 pairs.

I'll start trying with 4 pairs.

I have started the process of buying my cubic magnets (I found a seller), but don't paid for it yet. I hope 10 days from now I will have my 40 cubic magnets in my house.

[billmehess]

Thank you for the explanation. I think this is really worth pursuing. I can buy 1000 1/4" neo 45 cubes for $133.00 from CMS Magnetics. I am going to place the order and build an array as long as possible. With this number of magnets I should also be able to construct a circular or oval tract. It should be fun, anyway I love this stuff!

[Cherryman]

http://www.youtube.com/watch?v=Pxy8phi6I74

[Rapadura]

Thank you for the explanation. I think this is really worth pursuing. I can buy 1000 1/4" neo 45 cubes for $133.00 from CMS Magnetics. I am going to place the order and build an array as long as possible. With this number of magnets I should also be able to construct a circular or oval tract. It should be fun, anyway I love this stuff!

Things in Brasil are more expensive: I'm ordering just 40 neo cubes and 12 neo spheres for R$ 120 (120 Reais), what is the equivalent to US$ 65 or 70.

I notice you said you want to  "build an array as long as possible". My guess is that we should not build only one long array, the key is to build several Halbach arrays with only 5 cubes each (that is the minimum number of cubes to build a Halbach array).

The key is to place each pair of Halbach arrays a few centimeters distant from the previous pair, as Clanzer did in the video. It will be sucessfull if the speed gained by the roller inside the first pair of Halbach arrays is enough to overcome the gate (entrance sticky spot) of the second pair of Halbach arrays.

Let's try it!