Rosemary Anslie | Magnetic rosetta

[boguslaw]

@witsend
I hope you don't mind.

Original post by witsend:



Originally Posted by boguslaw :
Sorry that so late, but do you have a picture of arrangement of magnets ? I found it extremely interesting.
Reply:

Hi Bogus, at last someone's expressed interest. I've even tried to alert a 'magnet enthusiast' at Ou.com - to look at this. It's definitely off topic and no I do not have a diagram. But here's the thing. Buy your magnets first - ferrite is fine - but make sure that the n/s axes are at the top and bottom of the 'cylinder'. Not along it's length. You'll need about 12 - 16. Then cut the aluminium to fit so that the radial axes are are near the centre as possible. BY THE WAY - a small overlap of the magnets needed at either side of the alumunium to ensure that you can 'tie' it easily. So check that the outside and the inside diameters are slightly less than the length of the magnets. From memory I allowed a gap in the centre of about 1/2 inch. Then tie them with cotton thread. Glue won't cut it. Then hang them from cotton thread from the centre. The repulsive forces get very strong as you add to the build. It's great fun and quite an extraordinary result. It also retains a single justification which is quite unusual.

Actually I hope Harvey also reads this because I've realised, latterly, from youtube postings that he's also interested in magnets. It's an easy test to set up. I have other interfaces that I'd like to explore. But this one is indeed strange - simply because of that 'retained' spin justification. Not sure if it's typical but suspect not.

[boguslaw]

@witsend
I hope you can drop schematic later. English is not my native language and I must confess that without a picture it's hard to me to visualize that device.

[Mark]

Neat! I'm also interested.

Rosemary,

Let my see if I'm grasping what you describe. I picture a large aluminum washer. The magnets are cylinders (could they be rectangular blocks?) north poles facing toward the center, south poles facing outward. Magnets on both sides of the washer. Kind of looks like a flower with a hole in the middle? Then? Glue the magnets on or wrap with cotton gauze to keep the magnets on the washer? I'm lost now.

[witsend]

Hi Bogus and Mark. My friend has kindly agreed to draw the schematic. We'll post it soon. And Mark - don't try gluing. The repulsive forces are too strong. You need to tie the magnets on with cotton thread.

I'm sort of glad you took this off Aaron's thread but I'm not sure it merits it's own thread. It's just a short little experiment. In any event. It'll be the shortest thread in the history of the forum. At least it'll be here for the record.

Thanks guys. I'll post when I hear from my friend.

[ddmdragon]

Magnetic Device Pics

Hi All,

Rosemary has asked me help out with some visual aids

Hope it helps

[witsend]

Many, many thanks ddm. Such good schematics. Really a magic dragon.

Ok. So here's the thing. These have been shown as rectangular bar magnets. I've only tested them on cylindrical ferrites. The beauty is that the ferrites are cheaper, their width is narrower and you can fit many more onto the frame.

They need to be tied with cotton onto the frame. I literally used a needle and thread to ensure that I could knot them securely. So you guys are going to have to ask your wives / girlfriends to help - unless you're into sewing.

Then all I did was sew a small series of threads across the 'hole' and caught the centre with a long doubled thread. Just so you can suspend it from the middle. Then just let it hang. It pumps into action. Broad sweeping turns in one direction ending with that cotton rope twisted out of recognition. Then straighten the cotton and repeat. Nice toy - give it to your children to play with - but work out how to retain that spin. There's got to be something of interest if you can hang it from a frictionless bearing - maybe a magnetic bearing - if there are such things.

[Mark]

OK, thats what I had pictured, so the magnets can be flat then. The hard part will be putting the magnets on the ring. I would think glueing them first then wrapping.

Then the whole unit will spin in the air if you tie a string thru the middle and hang it?

Wit you posted before I did, got busy at work for a few minutes, I'll give this a try looks neat!

[witsend]

Hi Mark. Please consider testing cylindrical ferrites rather than flat - only because that's what I used and it works.

Delighted you'll test it. It really is a fun gadget. Should interest nephews, neices, grandchildren or children generally. And there's a puzzle here which may be worth attending to. How can one keep that spin? I just know nothing of the hardware required - but I've a shrewd idea that there must be a 'floating' bearing of sorts. Something that won't stall from the weight of the construct. I've got an idea that there are such things as magnetic bearings that would cut it. But I'm not sure that this is true or if it's something I also just thought about.

And that's another point. If magnetic bearings are not actually extant - consider getting this made. It's got to be an efficient gadget if there are two levels of magnetic fields aligned with opposing or 'like' poles. Truly frictionless - provided obviously the applied force is not extreme enough to overpower that 'repulsion'. Anyway - I'm either imposing on someone's patent or I've given an idea for a patent. Hopefully the end product will be a really good bearing.

[reddb49]

Tie something like a fishing line swivel on the end of the line, might just work. Something like this,

Fishing swivel - Wikipedia, the free encyclopedia

[witsend]

Tie something like a fishing line swivel on the end of the line, might just work. Something like this,

Fishing swivel - Wikipedia, the free encyclopedia

We obviously think on the same lines as I actually tried this. It doesn't work. And I also suspended with nylon thread - which also kills the spin. There's something about the twist in the thread that lends the arrangement its torque - but most anything hung will spin and then 'unspin'. These magnets just keep going and going. It twists the cotton in ever shorter lengths while the thread sort of tries to ravel into new levels of thickness. Hope I've explained that.

Whatever, it seems to pump with energy and describes really wide circles. I found it fascinating.

[Mark]

Hi Rosemary

So the picture posted is what you constructed except the magnets were cylinders. Did the cylinder magnets have a hole in the center or were they solid? And the "washer" was aluminum. Were the magnets on the top and bottom of the washers aligned with each other like in the picture? Do you remember the dimension of the magnets?

Thanks Rose

[witsend]

Hi Mark. The magnets were cylindrical - solid (no holes) and aligned like the magnets DDM shows. We also used ferrite magnets because they're quite cheap. Use as many as you can fit on the frame. And the frame was aluminium. I had it cut especially.

Love to know what you find here Mark. All I can promise you is that there's a really energetic spin. Quite intriguing.

[Mark]

Do you remember the size of the magnets? If your not sure just approximate.

[witsend]

Hi Mark - sorry I've just seen this. They were about one inch in length and about 1/4 inch in diameter. They were also 'snub nosed' rather than just 'cut off' at the ends - but I'm sure that won't be critical. Just align them so that they leave a small gap in the middle for you to get a balanced position to hang them.

[witsend]

BTW - I've seen that magnetic bearings are in use but usually with induced fields - rather than permanent magnets. I can see that it would be difficult to construct this wih permanent magnetised bearings - but surely still feasible. Anway - If possible, then I think one would possibly be able to retain that spin.