Magnabolt Box

Howdy, wonderful people!

Magnets are amazing, and this might be my favourite magnetic latching mechanism, purely because it relies on magnets both attracting and repelling, depending on whether the box is open or closed.

I shall explain! You see, this box has a hinged lid, and that lid has an arm on each side that can swing in once the lid is closed in order to secure it. It occurred to me that if the arms contained magnets that repelled each other they would push each other outwards, meaning that the box could close without those arms getting in the way. It also meant that the arms wouldn't rattle around when the box was open, which is a very satisfying thing.

But when the box is closed, those arms need to snap inwards to hold things securely! Initially, I tried to incorporate magnets for this purpose, but then it occurred that there was no need for that at all - just a piece of ferrous metal would do. So, I sourced an M4 bolt (probably from a long-deceased printer), checked that it actually was attracted to the magnets, and incorporated it into the design. And it works! Clearly the attraction to the bolt is greater than the magnets' repulsion to each other.

Oh yes, I should mention there are some push tabs on the side of the lid that pull the arms back to the open position, so that the box can actually be opened again.

So, to assemble this, the important thing is to make sure the magnets are oriented so that they repel each other. There's room in each arm for two magnets, but conceptually it should work with just one in each arm. I intentionally use pretty mediocre magnets for testing, so I doubled up (giving a magnet stack height the same as the magnet diameter, which is the limit to which it's useful to stack cylindrical magnets)

You can of course use any ferrous object in place of the bolt, as long as you can get it to fit :)

Print Description

This is an articulated model so take care that the first layer is nice and neat and that there aren't any print issues such as stringing or overextrusion that might bind moving parts together!

Magnets and bolt

You'll need four 6x3mm cylindrical magnets - two for each latching arm. You could possibly just use two magnets, depending how good your magnets happen to be!

You'll also want a ferrous M4 bolt or something similar that can slot in and attract the magnets! The model allows for the bolt to be up to 30mm long.

Print Dimensions

The Magnabolt box occupies 226mm x 78mm on the print bed and is 55mm tall.

Supports Needed?

Not at all!  Designed for straightforward printing!

Scalability

Scaling this will be tricky as it relies on the magnets to function, and those will no longer fit. So, if you're scaling, you'll probably want to have some other magnet size in mind :)

Print Orientation

The Magnabolt Box prints open, with the base and lid both flat on the print bed.

Happy printing!

xoxo

Sven.

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449 Magnabolt Box