Snap fit on an enclosure

[Greinon @mathilde Sweden]

I am designing an enclosure, and top and bottom should be linked thanks to snap fit. I have to use 3D-printing to make both parts. The material is ABS. I made some trials, but they keep breaking. I am using the design in the following picture. Do you have any idea about how I can strengthen them or something else to prevent them from breaking ? Thank you for your help !

• This topic was modified 3 months, 2 weeks ago by  Pete. Reason: moved

[uhuglue @uhuglue My Robox is a Green Kickstarter Beta]

I think the easiest way to do it would be to ensure that the latches are printed in the same direction as the flex. I have attached a picture so that things are a little clearer.

Of course, getting it to print in the desired direction will introduce its own challenges, so you could print the snap fit tabs separately and glue them in later.

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[BHudson @bhudson I have several Robox units Kickstarter and Commercial Arizona, USA]

@mathilde You are exceeding the bending stress of the material because the latching notches on your tabs are too deep. Reduce the length of the notch, or overhang, by 50% and see if you can work it.

The other possible solution is to increase the height of the latching tab. This will give more bending length, reducing the stress at the base of the tab and allowing more deformation during the snap action.

I operate two Betas and one Production Robox.
See my 3D Hub site at https://www.3dhubs.com/phoenix/hubs/ben

[Henry @henry My Robox is a Blue Commercial Version Washington State USA]

Another think you can try is to separate your clip from the side of the box by about 1 mm. By separating the clips from the sides of the box you have more spring action, more bending action and the clip will be less likely to break.

[click @click My Robox is a Green Kickstarter Limited Edition]

I’ve done similar to in my Raspberry Pi cases. I’ve been using 1.5 - 2mm walls, with 0.6mm recess (round in shape) and similar (1.5 to 2mm) tabs. Tabs are only 0.5mm wider. They work well enough and didn’t snap so far (and I have made quite a few boxes of various sizes using that recipe). I am sure it can be improved…

edit: forgot to add that I am using colorfabb’s PLA, but ABS must be as good as if not better.

• This reply was modified 4 months ago by  click.

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[Kent Hartland @heartlander My Robox is a Blue Commercial Version Kansas City, Missouri, USA]

See if this helps:

http://blog.fictiv.com/posts/from-snap-fits-to-adhesives-a-comprehensive-guide-to-mechanical-fastener-options?utm_source=Fictiv+Blog&utm_campaign=82a2d2b231-Content_Campaign_25&utm_medium=email&utm_term=0_2ae279895e-82a2d2b231-206404137

Kent
Damn Solid Design

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