I'm new to 3d printing and need to design and print a case on an Ultimaker S5 using PLA. The case is box like and consist of a top and a bottom part. I was thinking about cantilever snap-fits to join the two parts. I read that these snap-fits need to be printed in the X-Y-plane for better stability. However with the bottom/top side down the walls will be in the Z-axis and thus the snap-fits would be printed in the X-Z- plane. If I would print the part lying in it's side I would need a lot of support in the inside. How am I supposed to do this correctly?

Also what tolerances should I use to make the parts fit well while still being separable?

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    $\begingroup$ Welcome to SE 3D Printing! $\endgroup$ – Pᴀᴜʟsᴛᴇʀ2 Nov 5 '18 at 14:44
  • $\begingroup$ I removed the printer as this is not a printer specific question. $\endgroup$ – Trish Nov 5 '18 at 16:03

Let's look at the general design.... it is a case... so a box of to halves. And we need some kind of connector...

How about splitting the connector into a separate C-shaped piece? That way the connector clip can be printed with the C to the plane, getting maximum durability out of either pice. You just need to print some short overhangs, the clip going around the central box, possibly in dedicated notches. Also, this is easily removable from the outside with a screwdriver. And easily replaceable. Also, both sides could be identical, if designed in the right way.

Or we use a slot in the lower body, and a Y shaped slot in the top, and make the connectors have a flat hook that matches into the lower body (push in from below) then the split top pushes through the top and latches in... This isn't removable from outside easily.

Third alternative: bolts. If the item inside the box - a PCB? - is going to be bolted to the lower case anyway, why not add extra long screws and have the top case be bolted to the lower case with the same screw that holds the PCB in place? Or, just use a pair of additional bolts and nuts on the corners.

Edit: Recently, Angus aka MakersMuse uploaded a video discussing snap-fit connections and how to make them 3D printable with the example of a backpack buckle.

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  • $\begingroup$ I like the idea with the C shaped clamp. Is this better than pins on one part and holes on the other that make a press fit? This would at least be invisible. I have a PCB to put inside but I don't think it's a good plan to have the pins go trough the holes in the PCB because they could only be 2.5mm in diameter and would need to be about 18mm tall. Maybe I can make the case a little bigger and add Pins and holes in the outer corners? $\endgroup$ – xuma202 Nov 5 '18 at 16:39
  • $\begingroup$ C-clamps means, that your sides might be identical. also, some addition about using for example longer screws... $\endgroup$ – Trish Nov 5 '18 at 16:39
  • $\begingroup$ identical sides is not relevant for me because I'll need various cutouts anyways. Screws might be an option. $\endgroup$ – xuma202 Nov 5 '18 at 16:47

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