I am trying to understand the mechanism of a lip and groove locking system and how it allows two plastic bodies to stay together in order to make a protective box in which a cellphone will be placed. I am not fully sure on the material yet but I plan to use acrylic, but if anyone has any material suggestions (cheap/easier to manufacture/strong to survive a fall from 8ft), I'm all ears.
To me, it doesn't make sense how the lip and groove system is usually designed (the left picture shows the typical lip-groove cross section). How is that supposed to hold together?? Just a little frustrated haha.
What makes sense is the cross section in the right picture, if you use an interference/press fit. That actually looks like it will hold. I can't think of any fit that would allow the left picture to hold together. Is there an angle between the lip and the groove? Because if I recall, these usually don't have any angles between them, just clearances, which makes it more confusing.
Thanks for any explanations,