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WhipMag 3

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Tue Jun 30, 2009 2:59 pm PostPost subject:
diffident
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For OC:

Greetings. I've been thinking about your original "WhipMag" concept. Could it be that latches alone might be sufficient to make the motor work? I'm trying to figure out how to do that mechanically. I was wondering whether you were calculating the 18-inch diameter rotor that you were basing your calculations on using the same rotor and stator magnets as have been used on the WhipMag, and whether 18" was the exact measurement. It's been a while, and I don't remember where I saw it, but it seems that you refined that measurement a bit or inferred that it could or should be refined to slightly plus or minus 18 inches. Also: Have you thought about what the rotor might best be made of?

Cheers,

diffident
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Tue Jun 30, 2009 6:24 pm PostPost subject:
overconfident
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diffident wrote:
For OC:

Greetings. I've been thinking about your original "WhipMag" concept. Could it be that latches alone might be sufficient to make the motor work? I'm trying to figure out how to do that mechanically. I was wondering whether you were calculating the 18-inch diameter rotor that you were basing your calculations on using the same rotor and stator magnets as have been used on the WhipMag, and whether 18" was the exact measurement. It's been a while, and I don't remember where I saw it, but it seems that you refined that measurement a bit or inferred that it could or should be refined to slightly plus or minus 18 inches. Also: Have you thought about what the rotor might best be made of?


Since it hasn't been done yet, the actual requirements are still unknown.

It may be possible to do it with latches alone, but the latches introduce additional mechanical losses and additional magnetic resistance. I don't know if the additional torque gained from the repulsive relationship latching provides is sufficient to overcome these additional losses without some assistance. Magnluvin's idea of using tiny magnets as latches may reduce the mechanical losses by allowing the slowing of the stator to transfer energy back to the rotor. I've discussed that idea a bit with Harvey and Magluvin and it looks practical. The additional magnetic resistance can be reduced using the pivot mechanism I have described.

The 18" rotor size was determined by playing with some magnets on my kitchen table and measuring the distances with a wooden ruler. The basic criteria were:

1) spinning stator magnets should have minimal influence on each other
2) the rotor magnet should have a detectable force applied to it at every point in between stators (repulsive from the preceding stator, attractive to the upcoming stator, or both simultaneously).

For the magnets I tested, K&J D48 and R834DIA, the best stator-to-stator spacing I could come up with was approximately 4 inches. Now that's a seat-of-the-pants WAG measurement of the distance between poles. So add another 1/2" to get center-to-center spacing. So we wind up with 4.5" for stator mount hole spacing. For 13 stators that works out to 4.5 x 13 = 58.5" circumference, actually a bit more. Divide that by Pi, 58.5/3.1416 and get a little over 18.5" diameter for the circle of 13 stators, call it 19". There must be over 1/4" space between the stator center and the rotor's edge. If we call that 1/2" on each side, then an 18" rotor diameter will fit nicely inside.

A smaller rotor could be used if you wanted to have fewer stator magnets. For a 5 stator configuration, that would work out to 4.5 x 5 = 22.5" plus a fudge factor, call it 24" circumference for the stators. Divide by Pi, 24 / 3.1416 and we get a little over 7.5" diameter. Using the 1/2" center to edge from above, that would require a 6.5" rotor diameter.

All this is very, very, approximate, but if anything, I think larger would be better than smaller.

Or you could go for smaller magnets and scale things down that way. See the criteria I used above for determining the spacing.

My current plans are to design a rotor with adjustable, octopus arms that can be configured for diameters ranging from about 16" to over 20". The most difficult issue I'm facing at the moment is the stator design. I want a minimum of mass and a minimum of friction and I need to be able to attach a flinging arm with the tiny latch magnets at the ends.
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Tue Jun 30, 2009 9:12 pm PostPost subject:
Harvey
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I would like to see these measurements in a chart with mass distribution figures. The larger the combined rotor mass, the more sluggish its response to the 'force-period'. It seems we may want a very lightweight rotor itself that can translate its momentum to a remote storage system so that the transfer is done in a way that brings the rotor to a stop in position as the magnets latch into the force position. This will increase the period that the force is applied.

Why is this important? Recall from previous posts that:

`W = Delta E_k = E_(k2) E_(k1) = 1/2m Delta (v^2)`

( see [url]http://en.wikipedia.org/wiki/Work_(physics)[/url] for details)

This means that the change in kinetic energy of the rotor is where we get the work done from the magnetic forces. If all we are doing is maintaining a rotor RPM, aka momentum, then we really are not getting the full value of the forces at play. But if we repetitively accelerate the rotor from a near zero `E_k` to a max `E_k`, transfer that energy out of the system and use a little of it to position our magnets as necessary, then we will have a winning system.

We know that the WhiPMag II has sufficient force to move the rotor such that from a stopped position, subsequent magnetic interactions will not prohibit its momentum from overrunning the stator by more than 180° of rotor travel. Of course this is largely due to the conservative nature of the subsequent interactions, but the point is that a single well timed conversion of force to kinetic energy results in a substantial momentum even for this heavy HDPE rotor (258g). Adding diameter to this increases the mass exponentially.

Remember, we measure force as mass times acceleration.
And we measure work as vector force times vector displacement. In a rotational system, we measure this as torque times rotation angle (in radians).

So what does all of this mean? It means that the mass of the rotor is dependent upon how far you need it to move between magnetic interactions and how much energy you intend to extract from it during that travel period. And as OC has pointed out, this has minimums, because if we make the stators too close they interact with a negative impact on performance.

We then have a strength issue. As we become lighter, we become weaker. So there is a limit to how light we can make this and still support the force exchanges necessary. Recently I have learned that there is a porous, plastic material that resembles human bone when cured. It is lightweight and strong and may be just the thing for this type of endeavor.

Lets face it folks, you can put more energy into a merry-go-round from a stand still in a one-second push than you can in an hour of slapping it as it passes by. Wink

Cool

(I just realised that the math plug in is missing from Chrome Sad )
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Tue Jun 30, 2009 10:52 pm PostPost subject:
overconfident
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Harvey,

I almost agree. The rotor only needs to be able to overcome mechanical and magnetic losses. Any energy excess can be extracted and stored or consumed externally. As long as a greater mass doesn't cause greater losses (bearing friction), it's not an issue.

Surface area is probably a greater problem for a larger rotor (air resistance).

The slaps being delivered to the merry-go-round are pushing it at the speed of light (maybe more?). Rotor RPM should have very little impact on how much torque is generated. What's most critical is maintaining the optimal relationships between the rotor and stator magnets.

If speed is a problem, it will most likely be on the stator side of the equation. Those are the components that will constantly be varying their speed. That's why I think the stators should be as lightweight and as low friction as possible. In fact, this is my only reservation about using the tiny magnets for latching, it will add mass to the stator. I still think it's the best latching idea anyone has proposed so far.

I wish I could start building right now, but life keeps getting in my way. Even though I have over 80% of the thing completed inside my head, I probably won't even get started until my life settles down a bit, hopefully next year.
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Wed Jul 01, 2009 1:02 am PostPost subject:
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Surface area of the rotor can be minimized by using spokes instead of a solid rotor, but then turbulence would have to be considered.

My resonance tests prove conclusively that regardless of how fast magnetic information is propagated the force itself is constrained by the inertial reference frame; ergo, the slaps have little or no impact whatsoever at high rpm. In fact, if you will recall, the very high speed tests I did were so detached from the stators that the noise itself went away entirely rendering the magnetic forces moot.

But the point being made is that the rotor must go through an acceleration process for each energy transfer, otherwise the force becomes ineffective and momentum destroys the process by refusing to accept or release any kinetic energy.

I could start building tomorrow morning if I could just be made to understand what I am supposed to build and how it is supposed to work.


Cool
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Wed Jul 01, 2009 4:27 am PostPost subject:
overconfident
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Harvey wrote:
I could start building tomorrow morning if I could just be made to understand what I am supposed to build and how it is supposed to work.


OK, Harvey, here's a start. This is the rotor:

1" Lexan
12" diameter
3/4" hole for bearings
8 slots 3/8" wide and 1/4" deep to hold adjustable 6" long arms

The 2" recess near the center may be needed to mount the disc for the tinies up above the rotor, a little tower.

I didn't draw the holes yet, but I plan to have about 4 or 5 tapped #8 holes along each slot, between center and edge, for screws to hold each arm in place. Arms will have slots in them so they can be adjusted in and out.

The reason the lexan is so thick is so I can lay out 13 slots on the opposite side, so I can reverse the roles by transforming the spinning stators into spinning rotor magnets.

The rotor and stator magnets will be small modules that can be mounted near the end of each arm or on the base with a couple screws. I'm even thinking of cutting slots in the base so the stator magnets can be easily adjusted.

The fixed orientation rotor magnet bracket design is pretty complete in my head, including the pivots, but I haven't tried to draw it out yet. The stator module design is still giving me some trouble, but needs to have a compatible mounting capability so it can be interchangably be mounted on the rotor arms. I envision using 2 screws to mount either type of module on an arm.

Here's a 3D image of the rotor from eMachineShop. If you have the software (a free download), I can send you the .ems file.

http://s285.photobucket.com/albums/ll48/overconfident/WhipMagNew/?action=view&current=Rotor12.gif
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Wed Jul 01, 2009 7:24 am PostPost subject:
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I have a chunk of Acrycast - AX cast acrylic sheet 1.000 inches thick, 11.875 x 13.5 inches in the other two dimensions. I bought it on a surplus table and was going to make a whipmag base out of it before the WhiPMag II was envisaged. I can probably rig up a jig to route the channels, but before I do I'd like to have the arms already in hand for tolerance checking. I have my 3/4" OD 1/4" ID bearings from my original tri-layer rotor. I have the 8-32 taps so thats not an issue either. Of course don't expect this to have the precision that Madprof or Clanzer can provide as I am just using hand tools.

Of course before I spend any time and energy building this I still need to understand how it is supposed to work.

I think I can read ems files with eDrawings 2008, but if not I'll DL eMachineShop.

Do you need me to do any drawings in Visio or ACAD?

BTW, did you see what I explained regarding the maximum torque location?

Cheers,

Cool
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Wed Jul 01, 2009 2:39 pm PostPost subject:
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Harvey wrote:
I have a chunk of Acrycast - AX cast acrylic sheet 1.000 inches thick, 11.875 x 13.5 inches in the other two dimensions. I bought it on a surplus table and was going to make a whipmag base out of it before the WhiPMag II was envisaged. I can probably rig up a jig to route the channels, but before I do I'd like to have the arms already in hand for tolerance checking. I have my 3/4" OD 1/4" ID bearings from my original tri-layer rotor. I have the 8-32 taps so thats not an issue either. Of course don't expect this to have the precision that Madprof or Clanzer can provide as I am just using hand tools.


I'm not pushing you to build this. It's still probably a bit premature. But the rotor and adjustable arms are already gelled. Artwork has always been one of my weak spots. I'm still having difficulty figuring out how to use eMachineShop to locate, drill, and tap the 8-32 holes in the rotor, about 1" spacing from center and every inch thereafter.

I was planning on using 3/8" rod for the arms, just mill 2 sides flat so it is 1/4" thick and cut about 3 adjusting slots about 1.5" long in each one. The rounded edges should slide easily in the grooves and will reduce air resistance as things rotate.

Harvey wrote:

Of course before I spend any time and energy building this I still need to understand how it is supposed to work.


Remember those old antique thingies with a needle riding in a groove of vinyl, something our ancestors used to reproduce musical sounds? Anyway, some of them had a multiple play capability where you could stack multiple records on the spindle. OK, picture a 12" turntable with one 45 RPM record at the top of the spindle, locked into place. The turntable, spindle, and the disc on top all turn as a single unit. There are 8 tiny magnets mounted around the circumference of the top disc. (I know the image is flawed, in our case there's all these arms sticking out from the rotor with little rotor modules mounted on the ends).

I'm considering these tinies:
http://www.supermagnetman.net/product_info.php?cPath=29&products_id=81
or these:
http://www.supermagnetman.net/product_info.php?cPath=29&products_id=1084

I haven't figured out how to mount the tinies to the edge of the disk (arms) yet. I'm open to ideas. I think the tinies disc needs to have an adjustable diameter as well, but would most likely be just thin flat arms attached to a thin disc, something like an oversized CD-ROM disc, with arms of the same material.

I'll try and draw up the rotor magnet modules next. It's difficult to describe but should be obvious with a drawing.

Stators are more difficult and that's where my current design is stalled. I want stators to be as lightweight as possible. I've been thinking about using a carbon fiber shaft that is bonded to the diametric magnet and rotates as a single unit. The mounting bracket will need 2 bearings, the upper bearing needs to allow the shaft to extend through it, upwards high enough to mount the stator tinies where they can sync properly with the tinies on the rotor. Since the stator only has 2 tinies, it does not need a disc, only a lightweight, but fairly rigid arm (carbon fiber?) attached to the shaft.

I have considered using jewel or ball/cup bearings for the stator. But I don't think that would work well now that there is a requirement for the tinies. So the upper bearing must allow the shaft to pass through it.

Harvey wrote:

I think I can read ems files with eDrawings 2008, but if not I'll DL eMachineShop.


If you are simply sharing a graphic image, use whatever you need to produce it. But if we need to share detailed data, we should be using compatible software.

If you really intend to work with me on this, I think eMachineShop is the most you can expect from me for quite a while. It's the simplest CAD system I have seen so far, and for someone like me that's the biggest factor, and it's free. With eMachineShop, we'll be able to easily exchange fully dimensioned drawings. Also, you can help me overcome some of the simple, newbie issues I have and will have, such as locating 8-32 holes in the rotor slots.

If you want to work on your own (and I respect that), use whatever tools you are most comfortable with, and I'll try to do what I can with what I have.

I have some employment, personal, and health related issues that are all a bit higher priority for me at the moment, so won't be able to spend too much time on this until I can get some of them out of the way.

OC
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Wed Jul 01, 2009 2:58 pm PostPost subject:
overconfident
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Harvey,

I understood what you were saying about the maximum torque, but I still have some doubt about your analysis. I think the reason things smooth out and get quieter might have more to do with the rotational dynamics than the applied torque. I do agree that the torque would be applied for a shorter period of time when it speeds up, and apply less torque per transaction. But there will be more transactions to compensate for that.
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Wed Jul 01, 2009 8:49 pm PostPost subject:
diffident
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To OC and Harvey:

Interesting interchange.
And thanks for your helpful responses.
I’m going to have to backtrack into the forum to understand Magluvin’s “tinies.” I missed the part where there were also tinies in the central part of the rotor—I have access to the Internet at work, not at home.

I’m not sure that I’m envisioning device the way you mean, but a few thoughts:

As you say, Harvey, I could say, too: “I could start building tomorrow morning if I could just be made to understand what I am supposed to build and how it is supposed to work.”

OC, you say: “The reason the lexan is so thick is so I can lay out 13 slots on the opposite side, so I can reverse the roles by transforming the spinning stators into spinning rotor magnets.”

If it’s true that the device would be more likely to work with a fairly lightweight rotor, wouldn’t it be better—and not too difficult—to use, say, ½-inch material rather than 1 inch, and simply make two rotors, preparing the second for role reversal?

I need the drawing!

Please decide to work together on this.

Cheers,

diffident
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Wed Jul 01, 2009 9:27 pm PostPost subject:
Harvey
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Ok, I DL'd the eMachineShop program and reviewed the forum as well as a couple of vids regarding it's use and providing threaded objects (bolts and holes). Apparently, the program is limited in this regard and will annotate the drawing for threaded holes but will not portray them in the rendering. No problem.

It is interesting how tightly integrated the system is to the fabrication pricing and ordering interface. It looks like once you have it designed, they will fabricate it and send it to you. Very Happy

You have my email, go ahead and send the file so we can collaborate.

Cheers,

Cool
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Wed Jul 01, 2009 9:37 pm PostPost subject:
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diffident wrote:

I’m going to have to backtrack into the forum to understand Magluvin’s “tinies.” I missed the part where there were also tinies in the central part of the rotor


I'm not sure the description here will help much. I think my idea about using the tinies is a bit different than what Magluvin posted here. I have talked a bit with Harvey and did a napkin sketch for him about how it might work.

diffident wrote:

As you say, Harvey, I could say, too: “I could start building tomorrow morning if I could just be made to understand what I am supposed to build and how it is supposed to work.”


I'm not trying to dictate what or how to build something. I have my ideas and you guys have yours. Harvey asked for more information about what I am planning and that's what I have tried to explain. Do what you feel comfortable with. I'll keep plodding on at my own pace, but it may be slow.

diffident wrote:

If it’s true that the device would be more likely to work with a fairly lightweight rotor, wouldn’t it be better—and not too difficult—to use, say, ½-inch material rather than 1 inch, and simply make two rotors, preparing the second for role reversal?


If it's true, yes separate rotors would be a good idea. But if you read my rebuttal to Harvey, you'll see I don't think the rotor mass is a critical factor, at least within reason. Surface area and aerodynamics may be a bigger factor, but I don't see this thing turning faster than about 100 - 200 RPM. So air resistance shouldn't be a major issue either.

Quote:
I need the drawing!


Got eMachineShop? Got an email addy (PM me)? So far all I have is a rotor disc with grooves cut in one side. I still need to figure out the 13 grooves on the opposite side and how to locate, drill, and tap the 8-32 screw holes. And there are more drawings to come. I guarantee they will be crude.

Quote:
Please decide to work together on this.


I intend to work as well as I am able with anyone showing genuine interest and trying to make a positive contribution of any type. Please join us.
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Wed Jul 01, 2009 9:41 pm PostPost subject:
Droid
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Hi Guys, hope all is well
I use Alibre design for my cad drawings and they too offer a limited part free version.
For all my prototyping at work I use a place called QuickParts.
They do various styles of 3d printing and urethane molds for a good price.
Great on quantities and on line quoting based on your cad files.
If I can ever help render any ideas to 3d please do not hesitate to ask.
it's a stronger point for me then my magnetic concepts so if I can kick in in any way I'm game here.
Well Back to welding the mustang
Peace to all
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Thu Jul 02, 2009 1:58 am PostPost subject:
overconfident
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Droid wrote:

If I can ever help render any ideas to 3d please do not hesitate to ask.
it's a stronger point for me then my magnetic concepts so if I can kick in in any way I'm game here.


I'll keep that in mind. You can expect a few cries for help.

The Alibre looks interesting. I might give it a try. What I need is something "simple".
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Thu Jul 02, 2009 10:21 am PostPost subject:
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OC
Anytime, just send a sketch or some dimensions and I cad it out.
I can output various file types so compatibility will not be an issue.
I can also create 3d PDF's
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Thu Jul 02, 2009 4:05 pm PostPost subject:
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When you say 3D PDF's, is that an isometric wireframe view or some truly 3D thing I don't know about yet?
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Thu Jul 02, 2009 4:08 pm PostPost subject:
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Ok, I sent OC a new rotor file - I'm ready to cad the arms - an[color=red]y[/color] discussion as to how they should be?
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Thu Jul 02, 2009 4:26 pm PostPost subject:
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Harvey
in regard to pdf's
Its a full solid view, fully rotatable for viewing.
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Thu Jul 02, 2009 4:38 pm PostPost subject:
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Droid, That's awesome. I love the vector driven nature of the PDF's for zoom in capability. I must check this out. Thanx!

Cool
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Thu Jul 02, 2009 8:23 pm PostPost subject:
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Thanks, OC,

For taking the time to help me. I know your life is busy right now. And thanks for your invitation. I'm going to do whatever I can to help.

Cheers,


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Thu Jul 02, 2009 9:14 pm PostPost subject:
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Is there an OCMPMM Thread we should move this build to?

http://urad.net/forums/gallery/albums/userpics/OCMPMM_ARM.BMP

http://urad.net/forums/gallery/albums/userpics/OCMPMM_Rotor_13_Solid.BMP

http://urad.net/forums/gallery/albums/userpics/OCMPMM_Rotor_13_Transparent.BMP

http://urad.net/forums/gallery/albums/userpics/OCMPMM_Rotor_8.BMP

Had some trouble getting those into the gallery - they uploaded ok, but the gallery couldn't generate the thumbnails I think. So there's the hard links.


Cool
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Thu Jul 02, 2009 10:50 pm PostPost subject:
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@Harvey
in regard to PDF's
I will generate a drawing tonight and PM it to you.
I like using it to demonstrate renderings to managment and sales on the fly.
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Thu Jul 02, 2009 11:15 pm PostPost subject:
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Kewl.
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Thu Jul 02, 2009 11:56 pm PostPost subject:
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I just split the topic, calling this "WhipMag 3".

Images, animations, PDFs, and videos can all be placed on Photobucket. Videos can also be uploaded to the YouTube account.

There is a "WhipMag" account on photobucket. As far as I know, Yada and I were the only ones using it. I'll PM each of you the password in a little bit, just to make sure you have it. I just created a "WhipMag 3" folder/gallery. Have at it!

I have also decided to contribute my YouTube "WhipMag" account to the cause. I just changed the password so the same password will work for either Photobucket or YouTube. If any of you changes the password, please make sure to PM the rest of us.

Anyone else that wants to contribute to the effort, PM me and I'll send you the password.

NOTE: I might need to get to know you before giving out the password. Newbies, please be patient.

OC
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Fri Jul 03, 2009 12:33 am PostPost subject:
overconfident
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Harvey wrote:


Comments on your drawings, don't take this personal:

1) I think the arms should have about 3 adjustment slots, 1.5" long
2) There should be about 4 holes in each rotor slor, about 1" spacing
3) I think we can get a 5 slot rotor superimposed on the 8 slot one , using one of the 8 slots and adding 4 more.
4) If the rotor's threaded holes for arm adjustments on opposite sides will interfere with each other or come to close, they can be radially offset by 1/4" or so to avoid problems. Then they can be drilled all the way through.

5) And something I forgot to mention above, but I've said many times before, stator bearings should be nonmagnetic, plastic or ceramic. No magnetic bearings except the main rotor bearings.

Everything else looks good! Very Happy
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Fri Jul 03, 2009 1:26 am PostPost subject:
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1 & 2) I had originally thought of doing it that way for strength reasons but decided a hold down plate under the screw heads would suffice. The ribs between slots will interfere with certain adjustment locations - but if you feel strongly enough about it, I will change it up.

3 & 4) I attempted to do this and the track walls align with several of the screw holes. I think I will have to translate the existing tracks by some degrees of rotation and try again. This rotor is already out of balance*, I hope we don't need some of that material volume for balancing holes.

Gone for the evening - back late tonight.

Cheers,



Cool

*This is an optical illusion because of the hidden track that is perfectly aligned under the other. I just did a center of gravity computation and it shows the rotor perfectly balanced. Wink
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Fri Jul 03, 2009 2:34 am PostPost subject:
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Harvey wrote:

1 & 2) I had originally thought of doing it that way for strength reasons but decided a hold down plate under the screw heads would suffice. The ribs between slots will interfere with certain adjustment locations - but if you feel strongly enough about it, I will change it up.


I don't feel strongly. It just looks a bit flimsy with that long slot.

Harvey wrote:

3 & 4) I attempted to do this and the track walls align with several of the screw holes. I think I will have to translate the existing tracks by some degrees of rotation and try again. This rotor is already out of balance*, I hope we don't need some of that material volume for balancing holes.

*This is an optical illusion because of the hidden track that is perfectly aligned under the other. I just did a center of gravity computation and it shows the rotor perfectly balanced. ;)


3) Now that I think about it, it should be out of balance if we reuse one of the 8 slots as one of the 5 slots. It should be in balance if we could somehow cut 5 completely new slots that don't intersect any of the other 8 slots, probably impossible, so scratch that idea.

At the low RPMs I am expecting, balance shouldn't be critical, but something like 10 or 15 grams could easily cause major problems. There's plenty of meat available in that rotor, but figuring out just where to put a balance hole would be a real challenge. 8 slots on 1 side and 13 on the other will do nicely.

4) I think we should be able to find an 8/13 relationship where the screw holes don't line up with slot walls. If not, maybe we will have to go with the 1/2" material and make separate rotors, as Diffident suggested. That would probably make you happier too.
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Fri Jul 03, 2009 9:15 am PostPost subject:
Harvey
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Ok, I didn't get back as early as I hoped Sad - don't know if I will work on anything before sunrise - might need some sleep.

We may be able to use shortened tracks for a 5x pattern - I'll think on this.

Sometimes it is cheaper to machine two parts instead of one, there are a lot of factors. If I am using this surplus material, it won't matter to machine both sides.

I still need to understand how the magnets are going to interact so we can ensure maximum torque during the transactions. I get the simultaneous push/pull, and the transfer of energy from the stator to the rotor during the braking period, but I'm getting lost after the pull has ended and everything is in a balanced state. How do we flip things to get a new push/pull?

Confused
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Fri Jul 03, 2009 2:01 pm PostPost subject:
overconfident
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Harvey wrote:

We may be able to use shortened tracks for a 5x pattern - I'll think on this.


OK, but don't spend too much time on it. It's nothing important, just a convenience.

Harvey wrote:

Sometimes it is cheaper to machine two parts instead of one, there are a lot of factors. If I am using this surplus material, it won't matter to machine both sides.


There's pros and cons. 1 or 2 parts isn't important unless weight or surface area turn out to be critical factors.

Harvey wrote:

I still need to understand how the magnets are going to interact so we can ensure maximum torque during the transactions. I get the simultaneous push/pull, and the transfer of energy from the stator to the rotor during the braking period, but I'm getting lost after the pull has ended and everything is in a balanced state. How do we flip things to get a new push/pull?


OK, I'll try to get back to my cardboard mockup and put the pieces together so you can get a better feel for it.

I tried to use eMachineShop to design a rotor magnet module last night. There must be something seriously deficient with the right side of my brain. It doesn't seem to matter whether it's crayons or autocad, there's a disconnect between what I see in my head and what comes out on screen or paper (nothing new, I've been graphically challenged all my life). Or in this case, the software just gives me an interminable stream of error messages.

All I want to do is cut a 45 degree arc shaped recess, 1/4" deep, into a block of plastic. How hard is that? I spent a couple hours trying to do it and failed miserably.

I'll see if I can get my sweetheart to help me draw it out on paper.
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Fri Jul 03, 2009 7:36 pm PostPost subject:
Harvey
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Sounds like a sector of a hole chamfer.

The thing I have to keep reminding myself is that this program is 'machine' driven. IOW, if a real machine (mill, laser cutter etc.) cannot do the work needed to create a surface, the program fails. So to make a chamfered arc may require two parts to be joined at the center of the arc.

Wait...I just re-read your post, you want a 45° arc 1/4" deep - I got it - what major and minor radius?
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