Mechanical device trigger with variable time delay (100-500ms)

[tommy7]

This device, if it or something similar exists at all, needs to be completely mechanical without ANY electricity and be really precise and strong (to last a long time).

1. Press a button in order to trigger the start of the delay time. It must start only when the button is fully pressed down (or at a very precise and predictable moment in time)
2. The delay mechanism, whatever it is, will do its thing for the set amount of delay time after which it will popup the button/plate in 3.
3. The plate pops out
4. Fully extended (the time it takes for the plate to be fully extended from fully pressed in, should always be the same)

The delay could be set using screws, a lever, a spring, a ball for gravity or whatever, but it needs to be set very precisely. If set to X, the delay time should always be X. Times must not be off more than +/- 5%.

Is there even a thing like this...? if not, how would one devise a device like this?

When thinking about different solutions for the variable delay time mechanism, which really is at the heart of the device, I'm thinking that gravity would be the most precise way of achieving the same delay even after thousands of runs.

Like this:

1. Press the button which at the bottom has a magnet (in red) charged so that it will repel the steel sphere (in blue)
2. When the button is fully depressed, the magnet will release the steel ball which "hangs" in the black ceiling by a weaker magnet than that of the red repelling force). The black ceiling is variable in height in order to change the delay time.
3. The plate pops out after time X + the time it takes to push the black piston down fully into the tube
4. Fully extended plate

Now, this device also needs to have some kind of rewind mechanism. Haven't figured that out yet. But if the popup plate could be pushed in fully to reset the device that would be enough.

Ideas, thoughts?

 

[ChemAir]

Drag racers have a time adjustable spring button for trans brakes. Shim quantity dictates the time delay. Not sure if it will fit your requirements, though. A similar mechanism could be built with different weights, shims, and springs and accomplish something similar.

Slow reacting button.
Adjustment shims for the above button.

The above switches are electrical, but you may get some ideas based on how they work.

Can you tell us what you mean by "a magnet charged so that it will repel the steel sphere"?

 

[Baluncore]

https://en.wikipedia.org/wiki/Dashpot
https://en.wikipedia.org/wiki/Dashpot_timer

 

[berkeman]

This device, if it or something similar exists at all, needs to be completely mechanical without ANY electricity and be really precise and strong (to last a long time).

How do you reset it? What are the reset mechanism requirements? Why are those requirements important?

Oh, and Welcome to PhysicsForums.

 

[Dullard]

Pendulum.