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WhipMag 3

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Fri Jul 03, 2009 7:52 pm PostPost subject:
Harvey
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Is this what you had in mind?

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Sat Jul 04, 2009 4:53 am PostPost subject:
overconfident
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Harvey wrote:
Is this what you had in mind?


More like this, 'cept I don't think I got it quite to 45 degrees. The hole at the vertex is for the pivot pin. The other 2 holes are to mount to the arm.

http://s305.photobucket.com/albums/nn222/whipmag/WhipMag3/?action=view&current=RotorMag.gif
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Sat Jul 04, 2009 7:41 am PostPost subject:
Harvey
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Ok, I see what you envisage. Any preference as to the arc radius?
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Sat Jul 04, 2009 2:49 pm PostPost subject:
overconfident
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Harvey wrote:
Ok, I see what you envisage. Any preference as to the arc radius?


Well magnets are 1/2" long, it needs to be attached to some sort of magnet holder with a pivot hole. That will extend it a bit, maybe 1/4". I'd say 7/8" oughtta be enough. Might need to have a recessed area near the pivot pin to acommodate the magnet holder.

I have some soda straws that are a stretch fit over the magnets. Shrink wrap or something similar could also be used, but don't heat the magnet too much. In addition to cushioning the magnet against impacts, a short nonmagnetic insert with pivot hole can be superglued into the end. I have some wooden dowel I can use for a prototype. I'll see if I can find the time to take a photo today showing how that looks.

I'm thinking of using brass pivot pins (brazing rod?), but any durable nonmagnetic material should do. A pin made of carbon fiber rod or tubing with a teflon insert would most likely be one of the best material combinations for the pivot pin and bushing insert.

If the magnet requires some assistance besides centrifugal force to return to the outer edge, a weak, nonmagnetic leaf spring can be added.

Does this make sense?
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Sat Jul 04, 2009 6:40 pm PostPost subject:
Harvey
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Yes, it makes perfect sense with one small exception.
The way I see it, the stator fields are spherical and the same force that moves the pivot inwards on the approach will hold it inwards on the retreat. The net result will be a conservative action that steals energy from the rotor to move the pivot.

So, from my perspective, in order to be truly effective, we need to be able to force the magnet outward immediately after the equatorial pass, but the magnetic moment will be such so as to force the pivot to rotate inwardly. To put it simply, if the pivot moves inward at the same velocity that it moves outward, the action will be a wash and net to zero - assuming of course that the actions center on the stator magnet.

Both the leaf spring and the centrifugal force (assuming a constant velocity rotor) will be present for both the approach and the exit, so their contribution also nets to zero.

The only thing I need to evaluate here is the pin location which holds that pole position in a somewhat unmovable location relative to the rotor edge. That pole will be forced into the stator field at one angle and exit at another. If this occurs just as the stator is reducing velocity, the combined asymmetry may result in a gain of some type. But I don't see it (yet) adding much torque to the rotor.

Do you see the pin on the leading or trailing end of the magnet relative to rotor direction?

Perhaps we should provide a 90 slot with adjustable stops to allow various angels to be experimented with?

The maximum torque on the rotor occurs when both the rotor magnet and stator magnet are equatorially aligned with like poles facing the same direction. I know I have stated this over and over, but I think the point really needs to be emphasized because it is easily overlooked yet plays a critical part in the outworking of any plausible device.

I have some ideas here I will work on.

Cool
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Sat Jul 04, 2009 7:32 pm PostPost subject:
overconfident
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Harvey wrote:

Yes, it makes perfect sense with one small exception.
The way I see it, the stator fields are spherical and the same force that moves the pivot inwards on the approach will hold it inwards on the retreat. The net result will be a conservative action that steals energy from the rotor to move the pivot.


The pivot won't happen until just after the equatorial alignment. Repulsive force that causes the magnet to pivot inward will simultaneously apply torque to the rotor in the desired direction.

Harvey wrote:

So, from my perspective, in order to be truly effective, we need to be able to force the magnet outward immediately after the equatorial pass, but the magnetic moment will be such so as to force the pivot to rotate inwardly. To put it simply, if the pivot moves inward at the same velocity that it moves outward, the action will be a wash and net to zero - assuming of course that the actions center on the stator magnet.

Both the leaf spring and the centrifugal force (assuming a constant velocity rotor) will be present for both the approach and the exit, so their contribution also nets to zero.


Not if the stator is latched (or slowed) so it is still in a repulsive relationship as the rotor magnet returns outward. The amount of usable repulsion will be reduced by pivoting, but there will still be some there. Something is better than nothing.

Harvey wrote:

The only thing I need to evaluate here is the pin location which holds that pole position in a somewhat unmovable location relative to the rotor edge. That pole will be forced into the stator field at one angle and exit at another. If this occurs just as the stator is reducing velocity, the combined asymmetry may result in a gain of some type. But I don't see it (yet) adding much torque to the rotor.

Do you see the pin on the leading or trailing end of the magnet relative to rotor direction?


Pins will be on the leading edge when the 1/4 x 1/2" cylinders are on the rotor, towards the trailing edge when mounted as stators (spinny magnets on the rotor). The pin location is slightly beyond the end of the magnet so the leading pole will not be able to rotate any closer to the stator (increased magnetic resistance) during the pivoting action.

Harvey wrote:

Perhaps we should provide a 90 slot with adjustable stops to allow various angels to be experimented with?


The image in my head doesn't see anything useful beyond 45 degrees, but you are welcome to try anything you like. I'm just trying to share my ideas. You need to build what makes sense to you.

Harvey wrote:

The maximum torque on the rotor occurs when both the rotor magnet and stator magnet are equatorially aligned with like poles facing the same direction. I know I have stated this over and over, but I think the point really needs to be emphasized because it is easily overlooked yet plays a critical part in the outworking of any plausible device.


I haven't forgotten that. I just haven't benn able to get 'round to testing it. And I don't see any way to achieve that relationship without using gears to get things in sync. If you can figure out how to do it, let me know.
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Sun Jul 05, 2009 7:26 am PostPost subject:
Harvey
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Pivot Holder First Draft:


I think I will eliminate the recess and reduce the material to 1/4" thick. That will lighten it, reduce machining and allow the upper slot to be used for longer magnet assemblies if we so choose.

The current concept uses the single unthreaded hole for the pivot axle. The slots are used for stop adjustments. Springs could be used and the adjustments could serve as tensioning mechanisms. The slots allow clearance for a #4 screw while the two threaded holes (see disc in the hole center) are for 8-32 flathead screws with heads to be recessed into the arm and still allow the arms to be retracted for storage, transport or use. The pivot will still extend at least 1" past the rotor edge.

Design open for discussion.

Cool
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Sun Jul 05, 2009 1:54 pm PostPost subject:
overconfident
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Harvey wrote:
Pivot Holder First Draft:


Can't see the image. Problem at your site?
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Tue Jul 07, 2009 6:56 am PostPost subject:
Harvey
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Funny, I can see them both - In my post and in your quote.
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Tue Jul 07, 2009 6:58 am PostPost subject:
Harvey
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It would be nice to be able to assemble all the parts that eMachineShop creates into a complete assembly.

I wonder if that PDF program will do that...hmmm.
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Tue Jul 07, 2009 3:30 pm PostPost subject:
overconfident
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Harvey wrote:
It would be nice to be able to assemble all the parts that eMachineShop creates into a complete assembly.

I wonder if that PDF program will do that...hmmm.


Would be nice.

P.S. The image is coming through just fine now. Yesterday it acted like it couldn't access your server. Maybe your server was just busy at the moment (someone downloading a video or something?).
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Tue Jul 07, 2009 11:11 pm PostPost subject:
Harvey
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Here is the New Lower Mass design for the Pivot Holder

Larger Resolution

(The mounting holes were supposed to be #6-32UNC)

Cool
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Tue Jul 07, 2009 11:47 pm PostPost subject:
overconfident
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Harvey wrote:
Here is the New Lower Mass design for the Pivot Holder


OK, time for a couple questions:

1) What's the long slot at the outer edge for? I envisioned a thin lip or wall there to keep the magnet from pivoting beyond the edge. And I think it should be fairly thin to allow the rotor and stator magnets to get pretty close to each other.

2) Is the short slot for mounting some sort of "stop", and maybe a leaf spring as well?

Corners and edges should be rounded, more aerodynamic.
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Wed Jul 08, 2009 2:28 am PostPost subject:
Harvey
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1.) This a slider for an adjustable stop along the top to allow extension beyond or below 90

2.) This also is an adjustable stop, and yes I do see a leaf or long arm coil spring having a place in both arrangements.

Round edges add cost to machining and only matter when the surface speeds reach about 80 MPH for the material sizes we are working with. But there is a safety factor to consider at any cost.
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Wed Jul 08, 2009 2:45 am PostPost subject:
Harvey
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Also, the upper slot can be used for longer pivots if desired, or even mounting dual rotators for some feedback oscillations (going back to your original dream). So it gives us a few options.

Cool
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Wed Jul 08, 2009 3:39 am PostPost subject:
overconfident
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Harvey wrote:

1.) This a slider for an adjustable stop along the top to allow extension beyond or below 90


At its outermost position the magnet should be 90 degrees to the rotor radius. I think a thin almost 1/4" high lip would work well to constrain it there. I don't see any need for an "adjustable" stop. In my mind, there should be no more than 1/8" from the outer edge of the magnet poles to the outer edge of the bracket. The outer edge should also be curved so minimum clearance between rotor bracket and stator is at the center of the bracket. An 8" radius will probably do nicely.

Harvey wrote:

2.) This also is an adjustable stop, and yes I do see a leaf or long arm coil spring having a place in both arrangements.


I can live with that.

Harvey wrote:

Round edges add cost to machining and only matter when the surface speeds reach about 80 MPH for the material sizes we are working with. But there is a safety factor to consider at any cost.


Anything we can do to reduce losses is a plus. Safety is also worth some consideration. Cuts, bruises, and blisters do tend to interfere with my activity.
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Wed Jul 08, 2009 3:49 am PostPost subject:
overconfident
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Harvey wrote:

Also, the upper slot can be used for longer pivots if desired


I don't think longer pivots will be needed. Pivot point should be just a tad beyond the face of the pole, just enough so the leadin pole of the magnet can never get any closer to the stator than when the magnet is orthogonal to the radius of the rotor.

Harvey wrote:

, or even mounting dual rotators for some feedback oscillations (going back to your original dream). So it gives us a few options.


I did play around with some dual rotators, but that wasn't in my dream, just double vortices, N and S.
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Tue Jan 26, 2010 4:41 am PostPost subject:
overconfident
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diffident wrote:
@OC:

Any new thoughts or designs on how to do the latching mechanically?
Do you think that 13 stators are required, or can we work with the old WhipMag parts to work up a latch that works?

Cheers,

diffident


Diffident,

I moved this reply to the WhipMag 3 thread, where it belongs.

I was inspired by Magluvin for a different, magnetic latching concept, something he calls "tinies". I have the materials here now to build a prototype stator and see how well it works. Most of the info is here in this thread.

If you have any questions, ask away.

OC
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Tue Jan 26, 2010 9:42 pm PostPost subject:
diffident
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Sorry, OC,

Didn't realize I was in the wrong thread. I remember the "tinies"; seems I recall them as tiny magnets. (It's easy for me to be wrong.) Thanks; I'll review.

Cheers,

diffident
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Tue Jan 26, 2010 9:48 pm PostPost subject:
diffident
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OC,

I see my memory has failed me again. I see that you answered one of the questions I had a few months ago. I'll pay better attention!
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