Mechanics for modelling a push button latch spring

  • I am designing a door to put on a small enclosure that will open and close upon pressing a button. The idea is something similar to what you would find on an external DVD reader. My problem is with the actual button I understand I will need to use springs for this but I can not figure out the mechanics of the button.

    Are there 3D-printable, mechanical designs that could fit for this purpose?

    I interpreted the question in a manner indicating that Connor wanted to 3D print springs for the button. This would place his question within the realm of this forum. Why would there be currently four votes to close?

    @fred_dot_u, I firstly thought this was a request for a design job. However, as you point out, it is actually a request for ways to design a 3D-printable spring mechanism. I made some slight changes to the question in an attempt to highlight this.

  • A commonly seen method to provide spring action in a 3D printed model is to use a series of curved and straight segments. Some of the designs use the segment assembly in compression, aligned with the plane of the print, while others use the segment assembly for springiness perpendicular to the plane of the print.

    An example of the latter is a squishy turtle from Thingiverse resulting in four legs that provide some bounce to the turtle if dropped from a small height. This video shows the movement of the legs more clearly, as there were no suitable still photos available on the site.

    The image below shows another spring type print from Thingiverse in which the forces are in line with the print plane.

    springy thingy

    The S-curves cannot be too thick or movement will be severely limited, and too thin means impossible to print and possibly reduced lifespan.

    Many designs abound with a search of the 'net for "3D printed springs."

    PLA might be not the best option to print this design with, as it is not very flexible so after some compression and expansion of the S-curves they will become weak and might break. A good material for this design would be ABS or PET or anything that can flex a lot without cracking or breaking.

    A good bit of the durability will depend on the design and use, obviously. The aforementioned Squishy Turtle has been printed at the 3D printer in the public library (4 of them!) and are regularly handled by the general (not-gentle) public. The springy part continues to work after all these hands. In the case of ST, the spring movement is perpendicular to the plane of the loops, providing minimal movement over maximum mass. In the case of the above photo, this would mean that the button would deflect the latch bar downward and not to the left. PLA is rather brittle, yes.

    I believe you can adjust the lifetime of the spring by increasing the thickness of the S curves while also increasing the length of the springs (the greater the length, the lower the stiffness). Spring stiffness is roughly given by the formula K=AE/L, where A is cross section, E is elasticity and L is length.

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Content dated before 7/24/2021 11:53 AM

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