I looked for a topic on this but to my surprise I couldn't find one. So I'm making one.

I seen a few things on this site about magnets and making arms, weapons etc interchangeable. There seem to be these "rear earth magnets" that people use, which come in a variety of sizes.

So I have looked around New Zealand and found a few places that have these. I have found two different names for these Rare earth and Neodymium are these the same thing?
They also sound quite dangerous if swallowed and if a small bit chips of the magnet.

So I am making up my first Fell beast. I want to be able to swap the witch king and regular Nazgul around and also the armored head and regular head for maximum customization.

So I get the idea that you drill a hole for your magnet on each piece make sure get the poles rights then glue them in and your done.

Now a few questions:

Is super glue a good glue to use? Could the magnets be strong enough to rip the magnet out from the glue? or the impact of the magnet force the magnet to fall fall out.

Can you use the magnets with out drilling a hole first so it just has one face with glue holding it? for example on a pole arm being able to change the head of the weapon (of course you will need a tiny magnet for this).

Will the arm or whatever you are are using, sit in place with one magnet? will the arm turn too easily do I need to cut groves to make the arm sit in one position? or use two magnets?

Is the danger with these a real problem, has anyone had close calls or accidents?

What size do people get? I am thinking of a 2mm x 1mm seems small enough for a lot of uses. or do I want a few different sizes?

Some pictures would be nice to support you answers.

Thanks in advance.

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Neodymium magnets are a subset of rare earth magnets, but the most common group so the terms are nearly used interchangeably.

No idea what happens when you swallow them, so.. well, don't. A nice metal Black Numenorean model will also be dangerous when swallowed - and I reckon the limited flavour will not make it worth it either. Larger magnets may break, but it will take considerable effort to split a 1 or 2mm magnet in several parts.

A snug 1mm hole with a 1mm magnet inserted will nearly keep itself in place on its own, when almost entirely surrounded by superglue you'll have to destroy the entire surroundings to ever retrieve it. Very solid. Magnets may be strong, but no match for a large surface area held by glue. 2mm flat on a surface with glue should also hold up well enough.

Getting magnet sizes and their strength right is the real trick. A 1mm diameter magnet will hold up a plastic arm, but may not keep it in place very well (could easily rotate, or fall off on slight impact). 2mm is quite solid. 1mm can work for seperate weapons or hands however, and of course is the only option when larger ones won't fit. It may also be possible to combine pinning with magnets, the magnets to hold the parts together while the pins hold them in the right position. Or have one magnet slightly sunken in, while the other protrudes somewhat, for additional support (used this a few times in spearshafts). It's often probably best to use the largest magnets you can for the job at hand, until reaching relatively big ones (two 5mm magnets are difficult to seperate!).

For a plastic Fellbeast rider, 2mm would probably suffice, definitely if combined with a pin next to it (after all, plastic riders of rohan also sit on their steed with just a pin - with a magnet, you will however be fly upside down without falling off). Not sure of the surface area for the head, but the weight should be negligible although the angle is at a disadvantage. 2mm should still hold it well I think; it can hold metal parts pretty solidly.

Thanks for the amazing reply answered all my questions and more. I may as well buy some now.

The suppliers I have looked into and emailed like to brand warnings signs along with the magnet information. I thought the danger would be over dramatized.

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Glad to be of help.

Yeah, any magnets I got also tended to be supplied with a warning leaflet, and of course it isn't entirely silly. The little blighters are remarkably strong, compared to any fridge magnets or whatever people are more familiar with. Two 5mm diameter (1mm thick) magnets can stick together through the entire thickness of one's hand, and if a stack of those is on my desktop, all metal tools within quite a radius can be suddenly attracted to them (sharp knife blades etc...). Even so, it feels a bit extreme to warn for fingers being trapped if the accompanying magnets are 1mm in size - all you really risk with those is inhaling them.

It's quite likely the danger with eating them stems from the interesting and deadly chemicals that are produced when the metals in the magnets interact with stomach acid. This is also why eating batteries and coins tends to be a bad idea.

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