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> I don’t understand why it’s even considered safe to have one of these springs in one’s garage without a solid shield of some sort.

The shield is the steel tube that runs down the middle of the spring. When the spring breaks, it's got an integral safety containment, similar to the aircraft cable that is often run through extension style springs (which are probably far more dangerous when they break, though less dangerous to service).

> I’m honestly not sure why springs are common at all in this application.

They're nicely matched to the load profile of the door. As the door is fully closed, the spring is exerting maximum upward force. As sections of the door transition to the horizontal track, the spring is simultaneously relaxing some, meaning it exerts around half the force when the door is halfway up and very little force as the last segment hits the turn in the track. It's a pretty elegant match of mechanism to the load profile.

> A rather small motor with a lot of mechanical advantage can easily open a close a garage door, and if a DC or low voltage AC motor is used, it could do so quite a few times even if the power goes out.

Garage doors are actually fairly heavy. By balancing the weight with a spring, you do a lot of favors to your mechanical advantage systems. (Eg: less wear, less advantage needed, the door can open in a reasonable amount of time…) You also do yourself a few favors for when things fail. (Eg: you pull the safety release and it’s possible to open the door without the motor.) Finally, power isn’t free and motors aren’t either; A spring is a really cheap way to reduce the cost of both of these things.

I imagine that garage door openers would either need to be a lot beefier or would work a lot slower without the springs.

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

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.

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...

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.

Deep shafts have a tendency to flood. And that’s assuming you can drill one in the first place.

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.

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.

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

*Wrong link

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.

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.

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.

Plus a counterweight is a big fat weight hanging in midair, so it's pretty obvious what will happen if you let it fall (and where it will land), whereas with a spring it's much harder to tell whether it's under tension or relaxed, and what it might do when the tension is released...

Pistons are theoretically safer to work on, because you can depressurize them without physically manipulating them.

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).

Counterweight = a length of chain that lands in a bucket as the door goes up.

That'd be feasible for new-build uninsulated steel doors, but 200+ lbs of chain for wood doors is a lot.

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.

If the garage door opener breaks, or the power is out, many people might have a really tough time opening the door manually without those springs. They might not be able to even do it at all.

It is still, of course, a valid question to ask if it's worth having dangerous springs up there all the time for the rare event of the opener being inoperative.

Or maybe we just shouldn't have doors that are that heavy?

> many people might have a really tough time opening the door manually without those springs

I think that would be most people. Who can lift over 450lbs from the ground?

450lbs but because it is not straight up but up and back that probably gives a 2-1 leverage so 225lb or 100kg. using your legs to lift it would be in the realm of a regular male weight trainer but not the average jo or jane.

Sure it gets progressively easier as more and more of the door rides horizontally on its rails. But those first few inches where the door is nearly entirely vertical, must be some significant fraction of the total weight, probably >90%.

Not to mention you have to get your fingers or something underneath the closed door in order to begin lifting it in the first place. So the "from the ground" part is not insignificant.

All garage doors I’ve seen had a heavy yank handle on the inside.

That handle's for when the springs are working. It's probably not going to lift hundreds of pounds without breaking.

Your 2-1 leverage assumption is wrong. The first 1' is full door weight plus all the friction in the system. The effective weight will decrease as the panels transition to horizontal, but deadlifting 400 lbs is easier than overhead pressing 200 lbs.

They are surprisingly heavy, which is why you need such a beefy spring. When my spring broke a decade or so ago, I wasn't able to lift the door on my own, and with the assistance of my wife we were just barely able to lift it. Looks like they can easily be 200-500 lbs depend on materials (steel isn't light, but it's lighter than wood for this application), and I guess the issue is that you have to lift hundreds of pounds straight up against gravity.

Could it be made of lighter material. Ironic how the garage door is perhaps the most armoured part of a house

Lighter materials that would provide the same level of durability, security, insulation, and fire resistance would be significantly more expensive. No one wants to pay for that.

But the other 3 walls of your garage are wood?

The other three walls don't have the same demands put on them. For one, you wouldn't need to lift them by hand, so they can be practically as heavy as you want.

It’s less ironic in areas subject to hurricanes. They have a very large area. One of the most damaging possible sequences in a hurricane is when the garage door blows in, then the wind just blows the whole roof off.

I guess it depends what you make it of, doesn't it? Growing up I had a typical corrugated roller door, it was very easy for me as a kid to open it with some of the weight supported by the roller. I think they have springs but they're not as extreme as the tilt/section doors. Apparently you can throw a motor on the end similar to roller blind kits, and they wouldn't have to deal with as much weight as a spring-based door. Of course, I do not live in an extreme weather area (yet).

I lifted mine but probably shouldn't have. I kept sticking stuff under it, a crate, a stool, until I was able to put two step ladders under. The higher it goes, the lighter it becomes since now the horizontal roller starts to take on some of the weight. But it's super dangerous.

When the spring broke, one of them snapped, and the quickly dropping door snapped the other one as well. Surprisingly it didn't damage the door itself. It's a double door so had two springs.

I toyed with the idea of replacing the springs myself but after asking around doing a few searches decided it's best I pay a professional to do it.

My garage door is no longer connected to the opener, I just swing it up manually twice a day. My kid can do so as well without issue. Maybe mine is lighter.

Are the springs still in place? If yes, then they are still doing most of the work.

They exist, but are not connected to anything. It just swings on the rollers.

The springs are different than the opener. I don’t think the springs can be disconnected, they have to be carefully removed. You would know if they were or were broken, because you couldn’t open the garage door.

Side-mounted extension springs can be easily disconnected with the door up (and ideally clamped). GP describing them as "not connected to anything" makes me suspect that they're extension springs, which can be easily/casually inspected and determined to be not hooked up to anything. Torsion springs you probably need to look to see the marks on the spring wind up (or make a straight chalk mark on it and see if that twists uniformly).

The opener doesn't support the weight of the door, that's the springs.

That's why it's surprising how heavy the doors are. Springs make it very easy open and close the garage doors with one hand, so we get used to it. When springs snap, (they all have a limited lifetime) the doors suddenly feel surprisingly heavy.

Don't know your situation but I'd dare to suggest fix the opener, simply because it means not standing right underneath, you or your kid, when the springs snap. It was quite startling when that happened.

I recently accidentally drained the battery on my car while I was fixing unrelated stuff on the door (and therefore had the door open for 3 hours). I bought a "jumpstarter kit" which is basically a 12000mAh LiIon battery (3.7V) and some electronics. It's just a little bigger than a large mobile phone, but you clip it to the car battery and it's capable of providing 12V at 600A to turn the starter motor for up to 5 seconds. That's 7.2kW from a shockingly small device. I treated it with all due respect.

Some pedantry:

1. It’s unlikely there’s power conversion circuitry in the kit. It’s almost certainly a few cells in series.

2. I’d be surprised if it can actually produce 600A at 12V. It’ll be “12V nominal” into an open circuit, which is really more like 14V for a 4-cell Li-ion setup. But even a 600 cold cranking amp lead-acid battery only supplies 7.2V at 600A.

1: That's not what the manual says. But you're probably right anyway. I haven't cracked the box open to check.

2: Yes, you're right I'm sure.

I’m not an expert in how springs break but wouldn’t an ejection of material require the spring breaking in at least 2 places that are close enough to not loop around the rod? I’m curious if anyone’s ever been hurt by one breaking (other than when actively working on it).

I’ve also never heard of a shrapnel-based injury. Only door falls or torsion bars breaking arms.

I’ve actually replaced these in two houses, and yes, they’re dangerous, but honestly a little common sense and a straightforward (printed, with a buddy double-checking) list of steps you take with each quarter turn.

It’s super important to have the right torsion bars. Don’t try to invent your own.

I am a terrible person and have done this twice with a couple angle-ground pieces of rebar (almost perfect diameter) + a pair of vice grips.

On the one hand, nothing went wrong because I was careful. And rebar actually works really well.

On the other hand, it was pretty dicey, especially near the maximally-wound state when you're putting serious muscle into another quarter turn.

110% agreed on it being a 2 person job though. Reason #1: so someone is there to call 911. Reason #2: you'll need someone to cable up the drums while you're adjusting the spring, and it's way easier with 2 pairs of hands.

Realistically, any household maintenance task which needs a checklist and a second pair of eyes and arms to be done safely, is often going to be carried out by someone who feels that they can manage without either.

I'm far from an expert but many (most?) kinds of spring are hardened steel. It's not hard to imagine how they might shatter under the right stress.

Anecdotally, yes, it happened to me. An older extension spring setup where each end of the spring had a J-shape hook. The hook itself sheared off of the body of the spring and shot a ~2 inch steel boomerang across the garage. Fortunately my only injury was psychological and temporary.

The replacement spring was constructed differently, with the "hook" portion replaced by two complete loops of metal. The safety cable runs through that and would hold it back during a similar failure.

It’s usually a requirement that, in an emergency, you can disconnect the electric opener and open it by hand. Certainly if there’s no second door to the garage, this seems essential or you’d be trapped if power or anything in the opener fails. Springs make this possible.

The spring counteracts the weight of the door. In the event of motor or electricity failure a well adjusted spring/door will be easy to manually open. A direct drive/worm gear would require an uncoupling mechanism and the ability to lift the full weight of the garage door overhead to get out.

Attention is required when changing these, but they really don't pose that great of a risk. I've been present when one broke, and I've changed them myself. As noted by others - the spring stays contained by the metal shaft. They really aren't worth substituting with something that has more drawbacks when a spring's lifespan is on the order of decades.

> I’m honestly not sure why springs are common at all in this application.

Properly adjusted springs effectively cancel out the weight of the door. This makes it easy to open and close with and without an opener, and greatly limits the danger of a door falling closed under it's own weight, which can seriously hurt someone.

One of my garage door springs snapped unexpectedly while my housemate was opening the garage door. I'm glad nobody was under the door at the time since it slammed so hard it put a bend in the bottom section.