[Mitja Remus-Emsermann]

Hi all, I am worried about using (or even storing) a magnet with a pull power of 300 Kg. What is the minimal powered magnet that I should be able to use? Also it seems to be hard to source such a magnet in Germany.

 

Any advice? We are keen on trying the protocols to produce beads and to switch our lab to beads instead of spin columns.

 

Cheers, Mitja (Ex-Expat from Christchurch, now at FU Berlin)

[admin]

Ahoy,

Welcome to the forum.

First of all the 300 kg pull-force sounds even more scary than it is.
The magnetic field flux density follows an inverse square law and thus a small magnet,even one with 300kg pull force has very little effect on anything further away than a couple of centimetres.

Unfortunately this is also the reason why we recommend such a strong magnet. During the post synthesis & coating wash steps you will have your bead-rich solution in relatively large bottles. For the magnetic field to be strong enough on the other side of the vessel it has to be very strong on the side with the magnet.

To give you an idea what forces we are talking, here is a handy tool:

https://www.kjmagnetics.com/calculator.asp

If you insist on using weaker magnets you could use several of them distributed around the bottle.

Also, you can use a single, weaker magnet but the beads will take hours (or more) to move out of a ~2 liter suspension.

Cheers

Tim M

[Mitja Remus-Emsermann]

Hi Tim.

 

thanks for the warm welcome and answer. I like the idea of using several magnets, on the other hand, I am also weary about their attraction to each other and the resulting smashed finger or shattered magnets. I will try to get my hands on a proper butch magnet then. I also seem to have some issues sourcing the right kind of small ring magnets in Germany. My University doesn’t let us order from prestigious sources such as AliExpress, do you have a favourite German or European shop you are ordering from?

 

Cheers, Mitja

[admin]

Well yes, I cannot say I did not end up pinching my fingers a few times.
Just remember, it is only once the magnets get really close to each other that the force becomes huge. Hence you usually don’t smash fingers but are more likely to, well .. pinch skin.
So maybe just wear some leather gloves while you assemble whatever you end up creating.

Concerning a  suitable web shop, unfortunately I cannot help you there, I have not been in Europe in years and I just spent some time searching and could  not find the exact Magnets we specified available at any European shop either.

I did however come across this:

Here are my first designs of custom 3d-printed labware constructed with @adskFusion360 software and printed with @formlabs Form 2, at @PlantEvolution lab! #3Dprinting

(1) A magnetic rack for 96-well plates (23 Euro material cost): pic.twitter.com/TPlHSNASRt

— Uli Lutz (@ulrich_lutz) November 27, 2017

If he is willing to share the 3D files with you, those magnets look like they should be purchasable.

Best of luck

Tim M

[Mitja Remus-Emsermann]

thanks I’ll give it a go – it is a bit frustrating that the availability of magnets is so different around the globe.

 

Cheers, Mitja

[Author]

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