The Bucking Magnet Motor

[z.monkey]

I can already see that I'll be making more of these, and it may take several revisions to get it right...

Make it perfect on the first try?

I have yet to do that ever...

But Revision A is generally production worthy...

[z.monkey]

There are 44 magnets in the UABMM and they form a balance.  When you have a stall condition all these forces are equaled and at rest.  Now, by adjusting the clearances I can slightly tilt that balance, hopefully enough to cause one transition, and then a cascade, and  I am hoping that will make it go...

Point of reference is key.  Where is neutral?  What is a slight tilt?

This design is very wrong.  Now that I have a slight bit of experience with the actual device, albeit non-functional, I can look at it from many different angles.  The cants are way too aggressive, and the clearance is way too big.  Side currents (eddy currents) from the magnets are latching the magnets between each push.  The cants need to be slightly off balance, and I swung them over to 45 degrees.  LOL!  Well, hey, its my first magnet motor...

Need to let this fester in my brain some more.  I think it will get better with time, like sharp white cheddar.  So, I am thinking the balance reference for the cants is 0 degrees, directly facing each other, so there is no vector of movement.  A slight tilt would be 5 to 10 degrees (not 45).  Then the clearance on this one is a couple hundred mills, and should be more like a tenth of that.  Reducing the cant angle will hep reduce the side current interference and magnet latching problem.  Then also getting the magnets close together should also help reduce the side currents.

So the current UABMM is scrap, unusable.  This means UABMM2 is in the works.  The plate of Aluminum that I used to make the UABMM is $10, so material cost is pretty low.  But its also the part that has the most labor, so it costs the most really.  So, now with one built, having figured out the nuances, a second one will probably take two full days of machine time.  Plus all the magnets and hardware are reusable.  This will also give me a chance to make the Driver Ring mounting system better...

Awesomes...

[loosecannon]

a valiant effort indeed Z monkey.

im wondering if your current model could be modified to be a "testbed" of sorts for other magnet angles and such.

you could fab a bunch of small brackets that would allow you to mount magnets at different angles, then mount those brackets on top of your outer ring.
then you could raise the inner ring up to line up with the magnets on the outer ring.

not sure if your inner ring is useable or not, but the same idea could be applied to it.

this way, your assembly is modular and you can get much more experimentation out of a single build.

just an idea.
LC

[z.monkey]

you could fab a bunch of small brackets that would allow you to mount magnets at different angles...

Variable cants?  Not a bad idea, for experimentation, and for practical use.  There needs to be a way to "throttle" the motor.  Not just for use but also for stand by.  How do we turn it off?  Pull the driver ring?  Not very practical.  I thought about using a shaft mounted brake, but that makes heat, not good for magnets.  So the other idea was to swing the magnets out of each others influence.

Well, yes this is a good idea, but we are talking about 24 magnets on the driver and another 20 on the stator.  That is a lot of brackets.  And then if we wanted to synchronize those there are more pieces to be fabricated.  Like another ring which has a slot for each magnet.  Each magnet bracket has a pin which fits in the ring slots.  As the ring turns it alters the cants of the magnets, similar to an iris mechanism.  The ring then could be connected to a linear actuator, like a lever, which could be used as a throttle.  So, when we want the motor to go, we push the lever, which pushes the magnets into place, and the motor is in a run condition.  Then pull the lever to pull the magnets out of alignment, stopping the motor.

Yes, good idea LC, but what it comes down to at the moment is labor.  It is probably going to be easier for me to make a new plate set, than it would be to  design and fabricate 44 brackets.  But the idea is definitely something to think about in future designs.  Look at what some others have done to stop their magnet motors.  Perendev uses the "clamshelled" driver ring, and also tried pins.  Yildiz uses plate sections that have to be unscrewed and removed one at a time.  These are not very practical.  It works for an experiment, but not simple enough for everyday use.  Lutec's device is a mystery to me, and appears to be electromagnetic, so they are probably using electronic controls to throttle it...

Thanks, good idea...

[tbird]

hi z,

those brackets can be made fast and easy.  think decorative aluminum angle.  size to suit your needs.  mark spacing (unless you have a nice ruler on the mill), set up in mill vice and drill magnet mounting holes.  same for bracket mounting holes.  once drilled, set in miter box, with stop for length.  hack saw will make short work of separating the pieces and keep things square.

mount your rotor in the rotating table and score a line at the distance from the edge you want the brackets mounted.  same for drive ring.  you could use degrees or the points (formed by the previous machining) for distance between mounting holes, which can be tapped (easier than the first job).  since the angle alu. will be a bit thin, you may have to use a nut to hold the magnet on the bracket. 

there will be 4 magnets that you can't mount this way because of the guide pins & holes.  consider tapping the ends of those pins.  it looks like it might be a good distance (from outer edge of ring) to use as a reference for all drive ring brackets.  just turn the angle bracket 180 degrees and mount on top of pin.

i may not have covered all or been clear enough, but you are very handy when it comes to working your machine.  i'm sure you'll get the details right.

btw, it was just a thought.

tom