Bandylatch Box

Howdy, wonderful people!

I've finally got these things posted! Apologies for the delay and thank you for your eternal patience and support! ♥️ Right, let's see what this thing is, then...

Springs are interesting things, and I've mentioned before that I'm eternally hesitant about printed ones. That's almost certainly a silly position to take, but it's a good excuse to incorporate other materials instead! My favourite so far is magnets, mostly because invisible magnet power, but I just love the way it works in the Lodestone Latch Box, where two pairs of magnets attract and repel to effectively provide a spring mechanism.

However, it's not always convenient to pile lots of magnets into a print, so I figured I'd see what I could come up with using the colourful rubber bands I picked up for the Bandit Box. This time, though, I didn't want the rubber bands visible; they should be springy, but not obvious. So, let's see where things ended up!

I went through a bunch of approaches, including one that had latches where the rubber band held it firmly in either the open or closed position, kind of like a power switch, where there's a binary state, open or closed, and no stable in-between position. It didn't really work well, though, and that's absolutely a great job for magnets, anyway.

Eventually, I progressed towards a pinch-style mechanism, where pulling two latches in would retract pins, and from there it was a matter of working out how to route rubber bands in order to provide sufficient tension, to be able to keep the latch in the closed position. I also figured that there might be a risk that the band would not stretch effectively around bends, and all the stretching might just happen between the nearest bend and the moving part, so I did also aim to maximise the amount of band length between those two things. I'm still not actually sure if that's necessary, but overkill is better than... underkill?!

So, you'll need two rubber bands for the lid. The ones I'm using are No. 64 (87mm x 6mm) ones, but you can of course use anything that fits and has a sensible amount of tension. There doesn't need to be a lot of force involved - the rubber band just keeps the pins pushed outwards, and doesn't actually experience any of the force involved in keeping the lid in the box.

Just feed the rubber bands into the outlined-U-shaped paths, and it's ready to go!

Rubber Bands

As mentioned above, I used No. 64 (87mm x 6mm) bands, but you can use anything that fits and has an appropriate amount of tension!

Print Description

This is an articulated model, so make sure your first layer is nice and neat, and that there aren't any print issues like stringing or overextrusion that might cause moving parts to bind together!

Print Dimensions

The box body occupies 127mm x 80mm on the print bed and is 65mm tall.

Supports Needed?

Not at all!  Designed for straightforward printing!

Scalability

The tolerances in the lid are the main thing you'll contend with when scaling this up or down. If scaling up, the parts will get looser, but the rubber bands should help mitigate that a little! For scaling down, the issue will of course be whether the parts end up binding together during printing (and you'll need smaller rubber bands!)

Print Orientation

Both the lid and box print right-way-up.

File Location

You'll find this one at at 494 Bandylatch Box

Link to dropbox post: https://www.patreon.com/posts/31697592

Further Thoughts

Coming up with sizes for things like this tends to be fairly arbitrary, but in this case it was driven by the size of the rubber bands I had on hand. And the selection of those rubber bands was entirely based being the only size that came in multiple colours at my office supplies store.

So, ultimately, the size of this box was determined by stationery manufacturing and distribution! Actually, that's a bit disingenuous, since the lid and box could certainly be larger, and the latch could just stay the same, so maybe the impact of stationery logistics is really just on the size of the latch itself :P

Either way, though, it's interesting to reflect and realise where these arbitrary decisions came from! :)

Happy printing!

xoxo

Sven.