Oh Snap! 3D printing Breaking parts without breaking


One of the big advantages of plastic is that it can be relatively flexible. We see things that snap together all the time, but when 3D printing you don’t often come across interlocking designs. [Engineers Grow] has a video to help you design snap-in fittings that won’t break.

In the first video you can see below, he covers three settings that can help. The first is the length of the snap element. Second, the undercut size can be reduced. You can also try doing the snap; as thin as possible, although in the example it got too thin and ended up breaking the snap anyway.

The final suggestion, covered in detail in the second video below, is to change the hardware you’re using. The key parameter is called elongation at break. For PLA, the typical value is 8%. ABS is 10%, PETG is 24% and Nylon is 100%. Simplistically, you can assume that a PETG part can deform up to 25% before breaking. That may be true, but it will permanently deform long before that. The video suggests using 10 or 15% of the value to ensure the coin doesn’t lose its shape.

In the third video, you’ll also learn that print orientation matters. Growing the hooks out of the build plate leads to a weak hook, as you would expect.

We have already looked at the mechanics behind these. You can also find a lot of detailed technical data on the joints.


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