Mike TurveyAfter dozens of revisions, I've got a button that I feel is getting pretty close to meeting all the requirements. Here it is:
It's rather unassuming, but it is a highly reliable switch and takes only ~60g of force, with a uniformity of activation pressure across the top surface. Mechanically, this seems a really good solution.
Here is a breakout of the various components:
And here's a picture of the cap holder, and cap insert placed in the cap before being screwed down to the base:
And with the cap holder in place:
A key aspect to the "feel" of the switch is that when in its resting (non-pushed) state, the microswitch is already under some pressure, although not activated. If you don't do this, the switch will feel "sloppy" and rattles around. I found this to be tough to achieve consistently and reliably because it requires component precisions that near the layer thickness of the 3d printer (empirically, somewhere in the neighborhood of ~0.1mm).
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It's intriguing - please would you share more pictures of e.g. the inside of the cap or partially assembled so the principle of operation is apparent?
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Sorry about that. There were supposed to be more pictures in this log that appear to have been dropped when I posted it. I don't see a way to edit the log above, so I just posted a new one with pictures attached. And definitely more to come. This has been a really interesting project for me-- the tolerances ended up being a lot tighter than I expected. That said, I've been impressed at what a 3D printer can reliably spit out.
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Ok, I think there should be an edit button near the log title. Thanks! I wonder which parts of the tolerances are most critical and whether continued design refinement could remove some dependence on material or process tolerance. For example, if it's the height of a part that is critical, can it be made from sheet stock of that thickness to start with? Not a suggestion but an illustration of what I mean. Looking forward to more logs too.
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