5 ms·

What about a counterweight or a piston instead (pistons are used in pull down beds which might be a similar load)

nradov 2y ago
Sure, but then you have to put the counterweight somewhere which would occupy garage floor or wall space. And the counterweight track would have to be enclosed for safety.
- shiroiushi 2y ago
  It's easy: you dig a deep shaft under the garage and put the counterweight in there. Of course, there may be some cost issues with this solution...
  - naikrovek 2y ago
    you have an odd definition for "easy" I think. garage door springs are safe if you are careful and you use the correct tools and procedures. the instant you take a shortcut with these, you increase the likelihood of a bad outcome. so, don't take shortcuts, and don't do the work if you don't know what you're doing. the professionals know this and that's why we pay them, but they're not special creatures with special abilities; they're people who understand that this is a situation which can bite you, and they act accordingly. Just about anyone can change their garage door springs, if they do so correctly.
  - kayodelycaon 2y ago
    Deep shafts have a tendency to flood. And that’s assuming you can drill one in the first place.
MadnessASAP 2y ago
Still need to store the same amount of energy. A counter weight or piston also has more opportunities for uncontained failure. At least when a garage door spring fails it is still constrained by the shaft running through the middle. For what it's worth, I have also replaced my own garage door spring, and I really have no desire to do that again.
- Retric 2y ago
  The risk isn’t just what the spring does but what happens to something caught in it. Springs can release energy a lot more quickly than a counterweight which can only accelerate a 9.8m/s/s, and therefore more risky to disable.
  - MadnessASAP 2y ago
    A few hundred points accelerating at 1g is still plenty of energy. It also comes with it's own challenges when it comes to releasing it. It also provides a constant force, whereas the force required to raise a garage door linearly decreases the higher it gets. With the consequence that a garage door with a failed motor would slam into its stops over your head rather then into the ground. Followed shortly thereafter by the now liberated counterweight slamming into the ground. https://www.physics.smu.edu/scalise/www/misc/bricks.html https://www.physics.smu.edu/scalise/www/misc/bricks.html *Wrong link
    - Retric 2y ago
      Counterweights don’t need to take a straight path to the ground. The force a weight pulls on a surface is based on the tangent.
      - matt-attack 2y ago
        True but by adjusting the angle you still end up with a fixed weight throughout the run. A spring force changes throughout the movement of the garage door and that’s chosen to match the unusual fact that the garage door’s weight changes as it’s gets progressively rolled up onto the top rails.
        Retric 2y ago
        A fixed weight but not angle means the force varies. Cut the cable and acceleration would therefore also vary with that angle along the track. Springs make a lot of sense from an installation perspective and can be easily tuned to match the specific door design, but if I was working from scratch on a DIY project I would prefer to use a counterweight if there was somewhere it fit.
ethbr1 2y ago
See sibling comment above about the variable counterbalance needed for a normal right-angle tracked garage door. You'd have to match the counterweight to the varying load (i.e. garage door effectively gets "lighter" the more its raised).
- mhb 2y ago
  Counterweight = a length of chain that lands in a bucket as the door goes up.
  - ethbr1 2y ago
    That'd be feasible for new-build uninsulated steel doors, but 200+ lbs of chain for wood doors is a lot.
eternityforest 2y ago
Maybe there could be a mechanism that lets you decouple the spring from the door and instead connect it to a worm drive, which would then be used to take tension off the spring using a power drill, all while it's completely contained in a steel housing.

Sure, but then you have to put the counterweight somewhere which would occupy garage floor or wall space. And the counterweight track would have to be enclosed for safety.

shiroiushi 2y ago
It's easy: you dig a deep shaft under the garage and put the counterweight in there. Of course, there may be some cost issues with this solution...
- naikrovek 2y ago
  you have an odd definition for "easy" I think. garage door springs are safe if you are careful and you use the correct tools and procedures. the instant you take a shortcut with these, you increase the likelihood of a bad outcome. so, don't take shortcuts, and don't do the work if you don't know what you're doing. the professionals know this and that's why we pay them, but they're not special creatures with special abilities; they're people who understand that this is a situation which can bite you, and they act accordingly. Just about anyone can change their garage door springs, if they do so correctly.
- kayodelycaon 2y ago
  Deep shafts have a tendency to flood. And that’s assuming you can drill one in the first place.

MadnessASAP 2y ago

Still need to store the same amount of energy. A counter weight or piston also has more opportunities for uncontained failure. At least when a garage door spring fails it is still constrained by the shaft running through the middle. For what it's worth, I have also replaced my own garage door spring, and I really have no desire to do that again.

Retric 2y ago
The risk isn’t just what the spring does but what happens to something caught in it. Springs can release energy a lot more quickly than a counterweight which can only accelerate a 9.8m/s/s, and therefore more risky to disable.
- MadnessASAP 2y ago
  A few hundred points accelerating at 1g is still plenty of energy. It also comes with it's own challenges when it comes to releasing it. It also provides a constant force, whereas the force required to raise a garage door linearly decreases the higher it gets. With the consequence that a garage door with a failed motor would slam into its stops over your head rather then into the ground. Followed shortly thereafter by the now liberated counterweight slamming into the ground. https://www.physics.smu.edu/scalise/www/misc/bricks.html https://www.physics.smu.edu/scalise/www/misc/bricks.html *Wrong link
  - Retric 2y ago
    Counterweights don’t need to take a straight path to the ground. The force a weight pulls on a surface is based on the tangent.
    - matt-attack 2y ago
      True but by adjusting the angle you still end up with a fixed weight throughout the run. A spring force changes throughout the movement of the garage door and that’s chosen to match the unusual fact that the garage door’s weight changes as it’s gets progressively rolled up onto the top rails.
      - Retric 2y ago
        A fixed weight but not angle means the force varies. Cut the cable and acceleration would therefore also vary with that angle along the track. Springs make a lot of sense from an installation perspective and can be easily tuned to match the specific door design, but if I was working from scratch on a DIY project I would prefer to use a counterweight if there was somewhere it fit.

ethbr1 2y ago

See sibling comment above about the variable counterbalance needed for a normal right-angle tracked garage door. You'd have to match the counterweight to the varying load (i.e. garage door effectively gets "lighter" the more its raised).

mhb 2y ago
Counterweight = a length of chain that lands in a bucket as the door goes up.
- ethbr1 2y ago
  That'd be feasible for new-build uninsulated steel doors, but 200+ lbs of chain for wood doors is a lot.

eternityforest 2y ago

Maybe there could be a mechanism that lets you decouple the spring from the door and instead connect it to a worm drive, which would then be used to take tension off the spring using a power drill, all while it's completely contained in a steel housing.