Magnets for inflight mounting.

[seanrx]

My first Q on here 

So, am building some wheels up Spits and don't want to drill holes for a stand.

If I glue a magnet inside the fuselage, will it grip onto a steel stand? (I can fabricate my own stands)

I can buy magnets with up to a 3kg 'pull' of various sizes. 

Are these strong enough/too strong?

 

Edited September 17, 2020 by seanrx
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[dnl42]

Welcome aboard! 

 

You didn't say what scale, but the 1/48 Hurricane I just completed weighs 50g. So, why not try some magnets out? I agree too weak or too strong could be a problem.

[Work In Progress]

If the magnet and the stand are separated by a layer of plastic then it all depends on the separation, and the only way to find out is to test with a component. Magnetic strength drops off dramatically with distance. Really you want the magnet flush with the surface of the model.

https://www.intemag.com/magnetic-frequently-asked-questions#strength

[seanrx]

Hi. 

Ta for the replies.

That magnet strength table, great info there. Now I just have to choose a shape that'll fit flush onto the join when inside fuselage.

I'll take some pics of the fitting to post up.

[Vlad]

Have you thought about using circular/cylindrical magnets? That way you can drill a hole of the right diameter in the plastic, glue the magnet in and have a flush surface that leaves no separation (other than a little filler, primer and paint thickness). If the fuselage area is not flat, you can use several smaller diameter magnets in this manner, arranged in a line or square or whatever to best suit the shape of the metal stand. If you need it stronger, you can attach matching magnets to the stand instead of leaving it bare metal.

Edited September 18, 2020 by Vlad

[Black Knight]

23 hours ago, seanrx said:

My first Q on here 

So, am building some wheels up Spits and don't want to drill holes for a stand.

If I glue a magnet inside the fuselage, will it grip onto a steel stand? (I can fabricate my own stands)

I can buy magnets with up to a 3kg 'pull' of various sizes. 

Are these strong enough/too strong?

 

yes

I did a test with some very small magnets

Best is go for N50 or N52 rated magnets

No matter what the pull, its going to be blocked by the thickness of plastic. If you can, thin that area.

 

I did a test a while ago. This is what I wrote up for another modelling forum:

 

I have some small disc magnets; 10 x 1mm
They are N52, just about the strongest available


My test subject was a new tool Airfix 1/72 Gnat.
The magnetic force needs to get through this thickness of plastic;


1 wasn't strong enough, 2 was getting there, but 3 was even better
With three magnets laying flat to the belly I could get the Gnat to hang off a SM scalpel handle. It'll spin round, rock from side to side and fore/aft, but not fall off. It takes a right shake to make it do that

The magnets were held into the Gnat by white-tac around them; anything between them and the plastic reduced the magnetic force getting to the scalpel handle. It was a tight fit getting the magnets near the c.o.g. I tried them on edge but there was not enough magnetic force.

 

Adding magnets to each other increases their power, but only up to a point, thus 3 magnets each 10 x 1 mm stacked is = to 1 of 10 x 3mm and so on until the depth is greater than the diameter and you start to get a reverse in strength.

[seanrx]

BlackKnight.

Great info to read.

Have ordered 10x25 N52 rectangle, a good shape for a Spit, quite flat underneath at its wing/body joint.

Or magnet on the stand and a steel stud in place of the landing light. My Airfix 1.48 is a good choice for that, as i lost its clear part. 

Edited September 19, 2020 by seanrx
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[JackG]

From my board gaming days, I recall you could purchase flexible magnetic strips.   They can be cut to the required length, and would easily sit flush to the contour of the surface they attach to.  I can't comment on how strong they are for the intended purpose,  nor suggest a specific product.  They do come in the option of rolls, strips, and precut squares and some have a peel back adhesive side.

 

 

regards,

Jack