Mendocino Motor Under Construction

[d-m]

OK I like this, but confused about one thing on the magnets, you can buy them Axially Magnetized or Diametrically Magnetized see here
http://www.kjmagnetics.com/magdir.asp
it would seem to me you would want diametrically for the lift but axially for the rotation or will it even matter ??
Dave

 

[dsquire]

Yes the finer the ballance the better it runs in low light conditions. In particular its ability to self start.

I also posted another caveat in my thread - if you didn't pick up on it, I've repeated it below.

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 straight away - it will likely wobble itself off and away.
"Run it in" first.

Ken

Ken

I have been following along on this and find it very interesting. Regarding the balance issue, here is a quote that I found on K&J Magnetics web site which was posted by Dave (d-m).
http://www.kjmagnetics.com/faq.asp#time

I am not sure if this applies to the balance issue or not but will post it for you to see.

25. Will neodymium magnets lose strength if they are held in repelling or attracting positions for a long time?
In most applications, the answer is simply "no". If the magnets will be exposed to higher temperatures while in repelling applications, the answer is "possibly". The exact answer is a bit too complicated for a FAQ answer, and requires specifics about the application.

In any case there sure is a wealth of information available on K&J Magnetics web site regarding Neodymium Magnets.

Cheers

Don

 

[d-m]

OK I like this, but confused about one thing on the magnets, you can buy them Axially Magnetized or Diametrically Magnetized see here
http://www.kjmagnetics.com/magdir.asp
it would seem to me you would want diametrically for the lift but axially for the rotation or will it even matter ??
Dave

OK I'm thinking that either I asked a really dumb question and no one wants to hurt my feelers or there is no answer to this. So Ill ask if any one has ordered magnets if they could supply part # and suppliers
Thanks Dave

 

[boatmadman]

Here is a link to where I got mine from:

www.magnet-shop.net

and the magnets I used

(shaft RM-12x04x06-N and the bottom RM-15x08x06-N)

 

[Ken I]

Dave,
Not a dumb question as the magnets can be ordered polarised axially or radially.

The standard is axial - with opposite flat faces being North & South - that's the configuration needed for this motor.

Don,
Thanks for the links.

Regards,
Ken

 

[George_Race]

I got mine on eBay, here is the address:

http://www.ebay.com/itm/10-Neodymiu...095?pt=LH_DefaultDomain_0&hash=item22fe7e5097

The 1/8 center hole fits my brass shaft very nicely.

George

 

[d-m]

Thanks Ken and Boatmadman
now I have a place to start
Dave