Break through!

[gyulasun]

Hi Mondrasek,

Very nice setup, thanks and it is unfortunate it did not come out as a winning idea in practice.  Maybe it would be good to inform Butch about your findings, just to learn from it. However, he has left this forum...

Found a Flicker link to his recent ideas:

http://www.flickr.com/photos/lafonte_research_group/   

and on youtube he has a channel too:

http://www.youtube.com/user/LaFonteResearch

Gyula

[mscoffman]

modrasek,

Your going to hate me, but I suggest you modify
the central piece of metal to be more like Butches.
That is: 1/3 (fork)<-> 1/3 (disc) <-> 1/3 (fork), right
and left forks in sync. Then mount the magnets central
to the forks rather then at the edges. Also you may
want to create a return iron path armature for the
magnets like he has to boost flux strength.

The reason I am saying this, is that magnet fields are like
electrical currents and they seek out the path of least
(magnetic) resistance. So the path for both magnetic
fluxes when the end pieces are deasserted is through
the central area, which needs to have low magnetic
resistance (called magnetic reluctance) to the magnetic
flux. It needs to be wide and direct. The Magnets need
to have good access to it.

Having the end pieces in synchronization may allow
them to share lateral z-axis assertion energy. Hoping
anyway.

Maybe you have tried the above already? I just want to
remind that we don't know what the optimized parameters
are for various distances so it's best to cut and try approach
based on what has come before.

Here are some suggestions:
(a) try larger diameter, implying stronger magnets
(b) move both the magnets slightly toward the center
to create some "pilot flux" through the disc section
(c) try reversing the polarity on magnets such that
the flux crosses the central point.
(d) try to determine if the end pieces are "contact
sticking" - use a strip of teflon, to test if a track
of non magnetic material can ease assertion energy by
disallowing contact sticking.  This could be a phosphor-
bronze key bearing track in a production version.


---

mondrasek, good work so far!

Yes! => If you can get the end piece assertion forces
down to where Butch' s apparently were in his version,
I've done *a lot* of thinking about what to do next,
which I would be glad to discuss. I'm not speaking for
him, but Butch has got a lot going on with various
magnetic methods, so he may not be able to follow
through on everything that might be desirable.

:S:MarkSCoffman

[mondrasek]

Mark,

There are several reasons for the geometry I went with.  A major consideration was to try and minimize the mass of the center piece since just accelerating it from side to side is a pure loss.  Secondly I planned to use the ½ inch x ½ inch neos that I had on hand.  I made the end pieces 20 mm square in cross section so as to be good targets for those neos and minimize the mass of the center piece.  The distance between the slots is ½ inch as well since I choose a ½ inch shaft diameter and this was a good bearing size.  The OD was drawn at 50mm, but the machinist asked to just use 2 inch stock which was close enough.  I had also drawn up a 6.4 mm cam groove that fit nicely between the slots and was to accept a ¼ inch cam follower that would have been mounted centrally and cause the side to side motion as the pieces rotated.  I did not ask to have that groove machined since it would be very expensive (for me) and I wanted to first feel the forces at play.

I have positioned the neos central to the forks, at the ends, towards the middle, etc.  I saw no improvements either way.  If you maximize the force to rotate the end pieces by centering on them, then the force required to slide the center piece is also strongest.  Moving the neos off center appears to weaken both those forces.  I’ve found no way to strengthen one while minimizing the other.

Return iron armature is therefore not helpful since increasing magnet strength increases the force needed to slide the center piece proportionally.

Not sure how you think having the two forks in sync can help?  Maybe I do not understand what you mean by in sync?

In response to your direct suggestions:

(a)   I don’t think scaling the size up gains anything.  It only makes it more cumbersome and dangerous to work on.  And it is contrary to minimizing the mass of the center piece.
(b)   & (c) have both been tried with no apparent improvements.
(d)   I see no contact sticking.  You can slide the end pieces in and out of the slots with virtually no force when compared to the forces applied by the neos.  The slots were ground to their running fit tolerances.  The end pieces were lapped into theirs.  Very precise slip fit.

I think a good way to visualize the problems with this concept is to do so without the end pieces.  Just think what the center piece would want to do if rotated in the presence of the magnets.

I want to play with it for a bit more, but then I would be happy to loan it to you if you want to feel for yourself.

Sadly I do not have access to free machining services in order to try other configurations without considerable expense.  This one build was my present to myself for now, but I can’t afford to do these regularly.

M.

[mscoffman]

I want to play with it for a bit more, but then I would be happy to loan it to you if you want to feel for yourself.

Sadly I do not have access to free machining services in order to try other configurations without considerable expense.  This one build was my present to myself for now, but I can’t afford to do these regularly.

M.

Thanks for the offer. I was thinking that Butch might be interested
in seeing some alternatives to what he did. He could better compare
loadings etc. I do think that mag. return path through the air is going
to reconnect through the rotor. It would really be nice of him if he
could make something comparable to his unit available for further
experimentation. Kind of tune things up and give a thumbs up or
down relative to his unit. Yours is really a nice looking unit though. He
simulates magnetic flux stuff heavily so I trust he has dimensions
"about" right. I'm afraid the central metal in your unit is going to
be a show stopper though.

:S:MarkSCoffman

[zapjosh]

Very one in the world has to see this video.

http://www.youtube.com/watch?v=V6gaN8gRs5A