FM Concepts posts working video 4/7/2009

[magnetman12003]

I have not found any 8mm x 20mm rod magnets in the USA.  Shipping from overseas would be expensive.

I have nineteen  3/8 dia. x 1.25 long powerful rod magnets I can use to make this device. I know thats not what the inventor used.  They were not cheap.

I dont mind giving this a try using what I have but would only use a cement that when dry could hold the magnets in place.  Also of needed I could remove the magnets easily without busting them to pieces. 

Any cement/epoxy recomendatrions that can securely bond magnets to steel, plastic, or wood and still  be easily removed??  Mind you-- Hot glue gun epoxy uses heat which destroys a magnet quickly.  Thats out.

[ramset]

MagnetMan
Bill [Landon] used liquid nails,pL200-pL400 [home Depot etc..]
Still gonna be a pain to get apart [use the minimum]
Chet

[DMBoss]

I have not found any 8mm x 20mm rod magnets in the USA.  Shipping from overseas would be expensive.

I have nineteen  3/8 dia. x 1.25 long powerful rod magnets I can use to make this device. I know thats not what the inventor used.  They were not cheap.

I dont mind giving this a try using what I have but would only use a cement that when dry could hold the magnets in place.  Also of needed I could remove the magnets easily without busting them to pieces. 

Any cement/epoxy recomendatrions that can securely bond magnets to steel, plastic, or wood and still  be easily removed??  Mind you-- Hot glue gun epoxy uses heat which destroys a magnet quickly.  Thats out.

Well your mounting holes should not be terribly loose fitting, though that is tricky with the slanted ones.

But a thickened cyanoacrylate (Krazy glue), along with a "kicker" or accelerator will hold Neo's nicely if the fit is tight.  And you can remove the adhesive with cyano debonder.

Go to a local hobby shop and they have lots of professional cyano compounds and kickers and debonder. (always have some debonder on hand because you will glue fingers together at some point)

But don't spray the kicker at or near the glue bottle nozzle!  And try not to spray kicker on nearby virgin mounting locations....

the vertical magnets could be made to be a press fit if you had decent machining facilities - and then they'd not need to be glued, but you could press fit them and remove them easily.

or you could also drill and tap small stainless set screws through the edge of the rotor too, and hold the magnets that way. again this would make them removeable without a mess.

BUT for a press fit into bulk stainless - be careful.  it's hard and if your interference fit isn't right you will shatter the magnet.  It will take some trial and error on test holes in a scrap piece of the same rotor material to get the exact interference fit to work. (interference fit is where the bore is slightly smaller than the rod that is pressed into it - here probably only 0.0005" smaller or less)

A press fit into plastic to hold Neo's is easy, as the plastic deforms easily compared to the fracture strength of the magnet - but stainless is a different story.

DMBoss

[Craigy]

I thought i would knock this up, but although the rotor is the correct size i am using 12x 6 mm n40 neos.  Disc is perspex, and most of the neos are friction fit , no glue required.  The slanted neos are held in place using hot melt glue from a glue gun. Easy to apply and easier to peel off, which makes modification or removal of magnets fairly painless

http://www.youtube.com/watch?v=uWyWGT2Aois

part 2

http://www.youtube.com/watch?v=A24EKWIgZzo

the rig will work equally well ( Or Badly) upside down or right side up. Reducing air gap on these magnets below 15mm makes the rotor rise up the shaft..enjoy

[DMBoss]

I thought i would knock this up, but although the rotor is the correct size i am using 12x 6 mm n40 neos.  Disc is perspex, and most of the neos are friction fit , no glue required.  The slanted neos are held in place using hot melt glue from a glue gun. Easy to apply and easier to peel off, which makes modification or removal of magnets fairly painless

http://www.youtube.com/watch?v=uWyWGT2Aois

part 2

http://www.youtube.com/watch?v=A24EKWIgZzo

the rig will work equally well ( Or Badly) upside down or right side up. Reducing air gap on these magnets below 15mm makes the rotor rise up the shaft..enjoy

Craigy:

Nice try.  Yes it looked to my eye the inventor used hot glue on the tilted magnets in the hi res photos found at PESwiki.

That may pose problems with replication.  Most neos have a max operating temperature of 80 degrees C, and completely demagnetize at 350C.  But between these two temps some change or loss of magnetization occurs.

Hot melt glue is either 120C or 195C so he may have altered the magnetization of the tilt mags by repeatedly removing and regluing them this way! (which does not bode well for any replication, including my bet even he cannot replicate it if that is what makes it work) (just gluing the mags once probably won't alter them, but repeatedly removing and regluing them with hot melt adhesive might, especially if you had to use a heat gun to get the whole assembly's thermal mass up to the softening temp to remove or move the tilt magnets)(and altering the magnetic properties of the neos, is what Steorn's reputed effect is all about, isn't it?)(they [Steorn] say only "bad" magnets work - which could mean ones that are only partially magnetized)

But still you cannot conclude it doesn't work if the replication has not duplicated the geometry relationships of the magnets, and the mass of the rotor, and the same single bearing wobble he used. (all single bearings will wobble/tilt)... since the magnetic forces are inversely proportional to the square of the distance between magnetic field sources - tiny changes in geometry will have large effects!

And his center shaft/bolt is steel!  the black oxide finish on this socket head cap screw indicates it is hardened steel.  Also if he used 304 (18-8) stainless for the rotor, it is slightly ferromagnetic too!  Both these will affect the magnetic behavior of the whole system!

You can't do stainless on that toy lathe, but you could do brass, and it's about the same density as stainless....(hey I'm not knocking your lathe - having any one, even a toy lathe is better than nothing)  Also try the correct proportions for your magnet sizes.  In other words don't stick to his 70 mm dia rotor and 27.5 mm radius centerline for the mags.  Draw his in exact scale and use the proportions as a guide - like his magnet diameter is 100% with respect to the magnet circle, and the circumferential space between magnets is x % - and extrapolate that to your smaller magnets for circular positioning.

So you have to adjust your magnet circle radius to a smaller amount to retain the same magnet vs circumferential spacing relationship on the 22.5 degree intervals between the 16 rotor magnets, if you use smaller diameter magnets than he does. (you can't change the 22.5 degrees but differing radii makes different magnet diameter vs circumferential space relationship)

the rotor mass is important even if only from the flywheel mass point of view!  There is boost and drag torque occurring with this rotor.  And even if you had a small net boost torque, if the flywheel mass isn't big enough to store enough energy, it will not self run at a slow speed!

The inertia of the flywheel when it rotates has to be above a certain value to stay turning when it encounters the drag torque zones.  So even if you had a net boost torque of 0.0005 N-m, the peak drag torque will be in the -0.5 N-m range!  That will grab and stop a lightweight rotor, unless that rotor is spinning at say 1000 rpm!  And at 1000 rpm any bearing is going to have +.002 N-m of drag torque.

You need enough mass to "turn over" the drag torque humps at a slow enough speed to not encounter too much bearing and wind friction!  So lightweight plastic rotors - are not ideal by a long shot!

His is about 265 grams, for the stainless and magnets - which are both roughly 7.5 grams/cc.  Perspex or acrylic sheet is about 2.7 g/cc.

Also your dual bearings have wayyyy too much friction to begin with.  I just did run down tests of a light PVC rotor on a single full ceramic bearing and spun up by hand as you did, it takes 30-45 seconds to come to a stop.  Yours stops in a few seconds.  Way more friction than the inventor got net boost torque! (rule of thumb, the rotor/bearing should take 20+ seconds to come to a stop with a finger flick to get it going, in the absence of magnetic forces - less and your friction is likely too high) (one may need to try various different bearings to get it right)

IF this "motor" is real and not a hoax, by no means is a replication simple or easy!  He's spent what, a year of trial and error on this?  Going at it with less than accurate replication; in an afternoon or two and expecting it to work right off, might be a bit unrealistic.

DMBoss