Levitating Motor

[Ken I]

Here it is running at 50 rpm under ambient lighting (no illumination lights turned on).

The Windhoek Draught is to amuse Arnoldb - and I was thirsty.

This is to show it running with only one support end (as mentioned in prior posts two spoils the effect - but are there because I have grandchildren). The screws are loose enough to manually fold them up or down.

I took it outside in direct sunlight (low angle winter sun) and it spun up to about 1200 rpm before the collywobbles caused the rotor to strike the field magnets (I've only got ±1mm clearance) and it would have run over the fields and far away has I not had my hands in place for such an eventuality.

I think a couple more milimeters clearance would not hurt.

Ah well - it ticks over nice and slowly on my bar - day or night and that was the intention so I'm happy - Calling this project finished (for now).

Give me a couple of days to tidy up my drawings and build notes & I will post it under the downloads section.

(Sorry the vid's at the bottom but for some reason if I place it further up the post then everything below it dissapers ?)

Ken

 

[John Rudd]

Wow, I'm impressed... :bow: :bow:

How do I make one?

I need one like now so I can impress the guys at work ;D ;D

Nice job Ken..

 

[George_Race]

Hi Ken, great job! I just hope I can be as successful as you have been with your project.

George

 

[Ken I]

O.K. for those of you who may be interested I have finished all the documentation and drawings.

I've loaded it in the downloads section as a *.zip file containing the drawings as *.dwg, *.dxf & a single sheet *.pdf plus a *.doc file of the build notes.

Have fun but they'll cost you a KP point - and that's free.

Regards,
Ken

 

[arnoldb]

:bow: Well done Ken

And properly celebrated as well ;D

Kind regards, Arnold

 

[bearcar1]

Truly a bargain at twice the price, Ken,' I applaud you. Well done and thank you very much.

Jim
BC1

 

[Herbiev]

Well done Ken. It appears larger than i thought when compared to the bottle of local brew. Nice speed too :bow:

 

[tel]

Got 'em thanks Ken - KP paid in full!

 

[Ken I]

Postscript - Heads Up

I have been refining the balance by adding a dab of laquer to any repetetive high point when it stops at night - this is fine tuning to milligrams - and its easy given that the rotation is near frictionless.

However.......

This morning I noted that it is significantly more out of balance than it was yesterday and I have come to the conclusion that it is the result of either differntial curing of the lacquer or the wooden armature changing shape in response to changes in relative humidity.

I suspect the latter - bugger !

So if you are contemplating building this then make the armature out of stable materials (definitely not wood) - I am going to redo mine in acrylic (remember I ballsed up the wind in any case so this is the clincher).

A niggly point to be sure but if you want it to turn dead slow in low light conditions then this has to be right.

Hope I haven't caused anyone any grief yet.

Regards,
Ken

PPS Thanks for the KP's

 

[rhitee93]

I am happy to push you over 60 KP for this one. Many thanks :bow:

 

[Ken I]

WRT my earlier comments about remaking it in acrylic, I am going to add some M2 holes for the addition of balancing screws & weights which will be prettier than lacquered in lumps of solder - hopefully the bulk of the balancing weights will be attatched to the centre piece out of sight. Fine tuning will be by adding cheeseheads & washers or grub screws to these balance points.

I will post these amendments in due course but don't expect it for a week or two. The attatched photo might explain what I'm getting at.

I also have no idea what possesed me to paint the existing armature yellow. Too many Windhoeks perhaps.

In the meantime I see over 100 downloads in little over a day - seems to be attracting a bit of interest.

Ken

 

[boatmadman]

I am in the process of an acrylic version, first attempt at the rotor failed, only because I went for 23mm sq acrylic for 21 mm wide panels which didnt leave enough 'meat' for windings.

Next version I will be using 3 acrylic plates machined for the panels.

Regarding balancing, Ken, your idea for small screws in the centre piece is good. However, from a practical perspective, once the rotor is assembled and I have established the need for balancing, how do I get the screws into the center piece? Is it a case of going in through one end with a long screw driver?

Ian

 

[Ken I]

That's what the semi-circular cut-outs are for - to be sure its going to be a fiddly job.

Stainless AC screws should help here (make sure they are non-magnetic) otherwise use brass cheeseheds.

Get your gross balance by trial and error with modeling clay - replace with screws and washers (or turned bosses).

Do the fine / dynamic balancing on the ends - easier to get to.

Ken

 

[Blogwitch]

Ken,

With regards to you download, thank you very much for making it available.

I didn't exactly download it to make, but to understand it a lot better. Looking at the parts, with the shapes and how they go together, has now made it easy for me to understand what is going on.

I am a funny old git, I can understand things more from a planset than I can from text.

Keep up the good work

John

 

[Ken I]

John,
You're most welcome and thanks for the comment - from one funny old git to another - I know what you mean - sometimes I "get it" from the narrative - but more often from the plans.

Sometimes I just don't get it - the elbow engine eluded my comprehension for some time. Similarly I thought this levitating thingummybob must be quite complex and difficult - which as you can see it isn't.

Regards,
Ken

 

[tel]

I thought being a funny old git was mandatory in this game?

 

[AussieJimG]

Thanks Ken, looks like a great idea for a conversation piece and maybe some Xmas presents (yeah, but you gotta start early). KP paid willingly.

Jim

 

[Groomengineering]

Hey... Who you callin' old? :big:

Great work on the motor and the plans Ken, not sure I'll ever get one built but one never knows. ;D

Thanks and a KP.

Cheers

Jeff

 

[Ken I]

A final (hopefully) heads up regarding the levitating motor for those of you out there building one.

As I metioned previously, ballance is about the magnetic suspended centre rather than the mechanical centre. They should be the same but in an imperfect world they won't be.

If you leave the motor stopped (in the dark) and magnetically suspended, when you next try to run it its slightly out of ballance again and will not self-start in low light conditions.

My speculation here is that the magnetic field of the rotor magnets becomes displaced slightly from standing in one position. The resutlant shift the the magnetic centreline throws its fine ballance out of whack.

Running the motor for 30 minutes to an hour at moderate rpm's resets the field back to normal and ballance and low light running is restored.

Lessons :-

1) Store the rotor off its cradle when not running.

2) If it has been standing don't attempt a high speed "sunlight" run sratiaght away - it will likely wobble itself off and away.
"Run it in" first.

Ken