Info Needed for Spring Release Metal Bar

What is your preferred force multiplier mechanism?

How about an umbrella type mechanism...?

I think I would go with linear actuator...

Depends on lots of things.

1.) How quickly does it need to move.

2.) Does the movement need to conform to any kind of time/distance profile (for example a spring will exert more force at the beginning of its stroke; where, hydraulics will exert a consitent force).

3.) How often/regularly does it need to operate.

4.) How many are you expecting to make.

5.) What's the NRE (Non Recurring Engineering) budget.

6.) What's the production budget.

Rubber band powered spear gun? Or maybe compressed air spear gun? Trigger is your release button. Will need to add force multiplier (pulleys, levers, cams...specific to your application). Need repeatability? Check out Jorg Sprave's "Slingshot channel" for his various repeater slingshots, crossbows...

will this work?

https://en.wikipedia.org/wiki/Captive_bolt_pistol

Now for something a little more violent....

Take some leaf springs and some steel cable together with a cocking mechanism and trigger mechanism....

Large circuit breakers use drill motors to charge springs that open the breaker very quickly, also in that same charge cycle enough energy is stored to provide a quick close. The trip bar mechanism moves about 1/2 inch to release the spring energy, it requires about 3 lb. force pressure to release, often is done with a magnetic solenoid. A G.E. Vertical Lift Magneblast 1000MVA breaker mechanism will probably move 150kG horizontally across the floor, at least 10-20cm. This mechanism is about the size of 3 breadboxes, but could be designed to occupy a different space. No hydraulics needed.

You could make a cocking mechanism that used a car spring ...

...and have a steel bolt captive in the end that when the trigger release was pulled would slam into whatever was there...with great force...rather dangerous though...of course you could scale it down to something less intimidating, with say a motorcycle spring...

Here's a cheap option...a drill powered jack..

$43.

A few questions,

1. how did you plan on reset it?
2. does this cycle? or
3. intermittences usage? or
4. a one shot application.
5. does the mechanism need a controlled speed?
6. and most important, what’s your budget?

SE had a good one for a the cattle kill gun, keep in mind, some are powered with a low caliber cartridge. Also a nail gun comes to mind. That may give you an idea.

I know it’s not spring loaded,... but, As may have been mention earlier a linear motor may be your solution if your budget allows it, so I’m guessing you may want it as simple as possible.

the problem with spring loaded with the kind of force you require... the a pretty hefty spring. And I’ll see if I can find some some spring info such as ‘Hookes Law’ ^{sorry, about that} you’d need to at least be aware of, if I find it,... I’ll post it, hopefully in a more easily understandable manner, that would come from suppliers instead of academia...

Found some,... it briefly explains Hookes Law in a some what informative manner and also a downloadable about springs... I did look into it, but if it’s laid out like the overview, should help.

O.P. Kelly Protheroe, surely without disclosing the application, you could provide more information as requested by others in this thread. Otherwise it's like a party guessing game. Is it as small as a toaster or as big as a tank? Is it slow as a tortoise or as fast as a hare? Is it manual or powered? Will it operate once a minute or once a year? Etc., etc... Everyone has on their party hats, but they need more clues.

By coincidence I just solved a very similar problem. I have a large pile of wood on top of a couple of old wardrobes in my shed; I wanted to remove a large flat piece from the bottom of the pile; it would have taken ages to remove all the higher stuff, but, I wasn't strong enough to lift the pile with one hand whilst pulling out the piece I wanted with the other.

By good luck there was an old pogo stick in the shed; I tied a rope loop around the top and bottom (securing it there with tape); then I stood on the foot rests, and, put a loop from both sides of the rope around a stick which I then wound up 'til I had compressed the spring even more than my weight had done. I then jammed the pogo between a bin and a piece of wood above the piece I wanted; when I unwound the stick the pogo extended and lifted the pile so that I could "wiggle" the piece I wanted out.

Of course without more details of your reqirement, I have no idea how relevant this is. Certainly you could devise a better lock and trigger than the twisted rope and stick, and a couple of pogo sticks might just work for you.