Alnico and NdFeB magnets in stock in the states

[ctech]

so there where a few people that ask where to get the magnets and
since the Alnico are really hard to get in a matching size and grade i
thought ill provide them....


Ne528, 0.16usd each 1/8 X 1/8 inch axial magnetized round NdFeB 42 magnet
AL528, 0.16usd each 1/8 X 1/8 inch axial magnetized round Alnico 5 magnets

minimum order 3.20usd

shipping:
USA, USPS 3.00usd (only option for small orders)
Int, send me an email with an address and ill get you a price, item
will ship from VT 05060 USA

payment:
paypal
fees flat 0.50usd
address christin...@gmail.com
send a payment to that address with the quantity and part number

bitcoin
fees: 0.00usd
use Mtgox today's weighted avg as exchange rate https://mtgox.com/
address 15mrMJ52n9nVJoonfFwPY4pqxxxy4gYAp7
send me a msg with quantity, part numbers, shipping address and your
bitcoin address

[Niraj Jha]

Hi ctech,
We have a supplier that we buy Magnets from..
He says they manufactures Alnico as well as any other composition possible
in any shape or size..
If there is a certain type of Magnet that you think we should stock, let me
know we can stock and retail the same along with open-grab, for the Asian
and Australian markets.
Right now we have just two sizes..
http://fabtolab.com/index.php?route=product/category&path=68_120
Would be happy to add more..

Thanks and Regards,
Niraj Jha
+91-80-9578 2777
+001-415-251-9033
sa...@fabtolab.com

Fab.to.Lab
sElectronics 2.0
www.fabtolab.com
www.twitter.com/fabtolab
www.facebook.com/fabtolab

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[Kevin Berger]

Would physically larger magnets have greater "pull" (ie hold more mass than the current design for heavier payload), but be the same for the electronic part? Ie a larger quad copter or ground based 'bot use the same circuit, but larger magnets so it can lift more, but control it the same? I actually plan to use my open grab for a ground based robot, not a copter.

[ctech]

keven: no, larger magnets would decrease holding force....
your are limited by the field you can generate for realignment. holing
force is proportional to the area of the magnet but if you increase
the diameter you also need longer magnets otherwise they can not hold
there field of ~1.4T.
field energy needed for realignment is proportional to volume and
since doubling the area would mean 4 fold increase in volume,
effectively halving your holding force given the same magnetic volume
and field energy. keep in mind for this particular design requires
~15kW of power including ohmic loses for 100uS.... hence many small
magnets are better.
i am setting up to make smaller and bigger versions as soon as this
first stage of the project is complete.....
hope that helped, btw this is all in that paper by Ara Nerses Knaian
andreas