Vexatious Contrivance

Howdy, wonderful people!

Well, this is one of the more involved mechanical things I've come up with! Complicated linkages are a tricky thing for print-in-place models because parts can't be too close to each other during printing, but that also means there's a degree of play in each connection between parts, and when you link a bunch of moving parts together that cumulative slack in the motion can be rather dismaying. This design, however, is built around the lever being connected directly to the main moving part, which is the rear half of the lid. Then, that rear lid piece pulls the rest of the moving parts along with it.

So, what's actually going on in all those moving parts? Well, the lever pivots on the side of the box and pushes the rear half of the lid upwards. However, the rear half of the lid has that whole cog assembly going on, and what that does is rotate the lid as it moves upwards, so the lid lifts up and tilts backwards. Naturally, the front half of the lid is pulled along, too, but the front half is also anchored by another strut, so the lid is forced to fold along its centre hinge. Then, when the lever is pushed back, that same strut forces the lid to unfold as it lowers, while at the same time the cogs rotate things back to their original positions.

But let's look at the rest of the box! This box is comprised of layers, and there can be an arbitrary number of those layers. If you really want, you can just have the lid and the base! Each layer bolts into the one above it via a set of four bolts that run vertically through the corners, and those bolts actually serve as the attachment point for the layer below, too, hence the file name "chain bolt".

One nice thing about those bolts presenting a threaded interface is that this box has screw-in feet! Oh, and there's also a driver tool that fits in past the thread and into a hexagonal socket inset further into the bolt, to make assembly easier.

Print Description

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

Print Dimensions

The Vexatious Contrivance lid occupies 159mm x 180mm on the print bed and is 89mm tall.

Supports Needed?

Not at all!  Designed for straightforward printing!

Scalability

The tolerances are generous, so it's worth giving scaling a try! :)

Print Orientation

All parts print right-way-up, except the driver tool, which prints on its side.

Further Thoughts

A huge thank you to Courtney from Filament Stories (as usual) for test printing endless revisions to this model! All those bits of play in the system mentioned earlier do often mean that parts don't move quite as they're expected to.

For example, things that should in concept just rotate may move forwards or backwards and then catch or grind against something they're supposed to be keeping clear of. Fortunately there are techniques to anticipate and correct these problems, such as adding small ramps to divert motion into another direction, or trimming bits back until they can no longer catch on anything. But that's the great thing about 3D printing - we can make our fix, run off another test print, and see right away whether things are now behaving themselves!

Happy printing!

xoxo

Sven.

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514 Vexatious Contrivance