Compact, light, reloadable sear (trigger) mechanism

Post date: 2026-11-13 05:20:38

I am trying to build a tiny RC mechanism to: 1) load a spring with about 12J 2) hold 3) release that load instantly 4) re-engage for another round I have roughly 80g to work with, and I would love to do all of this with one tiny servo or a small motor like an n20. I can think of several ways to load the spring, but I cannot picture releasing with the same motor.

The goal is to launch a one pound robot in the air after it reaches the launch plate (but before it escapes). Load time can be longish (like 5 seconds).

The current spring concept is a steel or carbon fiber bar, deformed downwards by either a cable or a cam or an incomplete gear plus rack combo). Depending on needs, worm gear to prevent back driving the motor is doable.

I'm trying to learn about release methods that will work.

RC glider tow release sounds promising
An airsoft trigger mechanism (or a part thereof) seems designed for this.
For either of those, I can only imagine a second motor (a servo) that pulls a pin and resets it.

The cam and incomplete gear (mutilated gear might be your term of reference?) both have two problems I can imagine: they have to hold lots of force when loaded (though the cam could look like a compound bow cam, which reduces force needed to hold), and they would easily rotate to the released position if I hold that motor on for an extra second.

This is surely a problem that was solved before the industrial revolution, but I don't know how to look up options.

I'm open to machining a custom part, or not, depending on what will work.

I'm looking for a "here's the book published ages ago with options", or "actually, there's a servo motor that can magically disengage to release quickly without frying electronics" response, but a "you're thinking about this wrong" could help if it's true.

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