Hi Guys

Does anyone have any tried and tested methods for building a release mechanism that they would be kind enough to share?

I'm talking about the type that is used to trigger 'something', where the effort is far less than the force or load. I've seen systems and also have older props, that use a series of levers to reduce the effort required but wondered if there are formulas or principles to be aware of.

I'm pretty adept at engineering most things but this is causing a few headaches and creating piles of scrap brass. I knew I should have paid more attention in physics class!

Any help greatly appreciated and please feel free to PM me so we're not divulging any secrets.

Nick

A lever consists of a "beam" and a fixed "fulcrum". Given a fulcrum (hinge point) with "zero" friction, the ratio of output to input force equals the ratio of the lengths of each side of the beam - so if your beam is 3 inches long and you have 1 inch at one and and 2 inches at the other the magnification of the force will be 2-to-1.

In the above example, if your 1-inch side is the input and your 2-inch side is the output then it will require twice as much force to move the lever - but the output end will move roughly twice as far. The opposite is also true - if your input is 2-inches long and output is 1-inch long you will put out double the force with half the travel.

When I was younger and less adept at building, I wanted my tilt-n-table to release on queue. So... knowing that the mechanism was timed but very innacurate I set out to revamping the mechanisim. What did I do?

I used a mouse trap. I built an extension from the base that went behind the mouse trap. I had a motor hooked up to a wireless doorbell. Whenever I tripped the wireless doorbell the motor would slap down on the mouse trap releasing the table. It worked every time.

If I were to rebuild this with current technology and my better building skills I wouldn't go this route. It would be 100% digital. The mechanisim itself would more than likely involve a spring similar to that of the mousetrap. I have a project I need to rebuild that also faces the same issue. For that I will likely look into spring release hooks (light duty). Who knows, I might just retrofit another mouse trap.

Kind of difficult to comment without more specifics on the direction of load and release. The best solution will be dependent on the specific scenario.

Many thanks for your input on this and also the folks who sent a PM. I'm getting closer to a solution.

For your info Raven, it's a small device that is spring loaded where the direction of load is vertical and the release is linear, the release relies on a small(ish) solenoid which isn't mega powerful, hence the need to reduce the force required.

If you are familiar with this gimmick for the exploding toilet seat prank, it uses a very low force release on a reasonably strong force. You could probably apply the same principle to your situation.

https://www.google.com/url?sa=i&rct=j&q=......70184562

Here is a pic to illustrate above. Red is hinge. Black is release. Leverage of hinge makes release low force. Contact points should be metal and minimal to cut friction as much as possible.

Click here to view attached image.

Cheers Raven, think I have one of those devices that came with a Sparks Bullet catch. I'll take a look.

Nick