Why are we still using springs?
It's an American upper middle class thing.
How I replaced deadly garage door torsion springs (2002)
321–330 of 344 posts
Re: How I replaced deadly garage door torsion springs (2002)
#322Earlier quoted context omitted.
I knew someone in high school who had started work at an auto repair place, and he described the process - and danger - of replacing car springs to me once. I'm sure there are various types of car spring, the kind he was talking about was the stereotypical coil-of-metal spring. There's so much energy in there that a small slip up can be deadly.
It used to be worse. Lots of cars today use a coil-over-strut design that captures the spring. There's still a lot of energy, but it's much easier to manage safely, by the time the nut at the top runs out of threads there's generally little to no force left in the spring. Way back (like... 30 years ago) when I was working on my Mustang, the spring was separate from the strut. You had to drop the control arm enough to…
The back springs in many cars are still separate from the shock absorber and it is those back springs which often fail. I have replaced them on several cars and can only conclude that the job can be done safely as long as you use a pair of reasonable-quality spring compressors - two of them, one on each side of the coil so that it can not pop out. These are used both during the unloading of the old spring as well as when installing the new ones.
Re: How I replaced deadly garage door torsion springs (2002)
#323Earlier quoted context omitted.
I’m baffled too. Changing oil in a car is dead simple and effectively zero risk with a proper pair of jack stands and a modicum of common sense and mechanical aptitude.
Harbor freight famously sold unreliable jackstands for awhile. There’s memes about it in the car community.
There's plenty of unreliable jack stands, especially the folding tripod-type is easily toppled. I still use these but I put a few LECA-blocks and/or stacks of lumber under the edges of the car to catch it in case the jack stands fail. This never happened but I prefer not to end up a statistic of the ´man found dead under car on farm' type.
Re: How I replaced deadly garage door torsion springs (2002)
#324Speaking of things you shouldn't do yourself, I should really get around to replacing that ceiling fan remote unit.
Re: How I replaced deadly garage door torsion springs (2002)
#325Earlier quoted context omitted.
At least according to the article, the main failure mode is fatiguing, so I’m not sure lube would help with that, unless the corrosion is really bad. Most materials have a finite amount of cycles in them (although I’m a bit skeptical of the authors 7 year estimate…it seems low to me)
Roughly 30k cycles is typical. You can certainly design a spring to have infinite life. But it requires reducing average deflection, aka more spring with less deflection per turn.
The article claims a 10k cycle limit for common-grade torsion springs (but again, I'm skeptical). You can design a spring to have infinite life. Still, you must constrain yourself to specific materials (steel and titanium being the most common) because most materials don't have an infinite life on an S-N curve.
Re: How I replaced deadly garage door torsion springs (2002)
#326Good article, but the author is using low numbers for the "speeding bullet" stats.
Like many jobs both around the house and industrial stuff, know what you are doing before you attempt it. But go away with the "it's too dangerous for mere mortals" speeches and special legislation to protect us all. Many people are capable and willing to do work that is hard and or dangerous. Snowflake legislation doesn't help the world work. Darwin awards work for the betterment of society.
Re: How I replaced deadly garage door torsion springs (2002)
#327[deleted]
Re: How I replaced deadly garage door torsion springs (2002)
#328Earlier quoted context omitted.
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.
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.
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Re: How I replaced deadly garage door torsion springs (2002)
#329I had a teacher in high school who was blinded (I think only in one eye) trying to do this repair. You could not pay me enough money to do this repair. >This work is risky, but the risk is comparable to doing your own car repairs, or climbing on the roof of your house to clean your gutters. Notably, "unintentional fall" is the #1 cause of emergency department visits for adults [1], which is why I'd hire a professiona…
It's amazing how comfortable people are with stored potential energy... I do not like powerful springs and bungee cords and the like.
But plenty of people are fine with roofs and springs but terrified of electricity
Re: How I replaced deadly garage door torsion springs (2002)
#330Earlier quoted context omitted.
What about a counterweight or a piston instead (pistons are used in pull down beds which might be a similar load)
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.
Pistons are theoretically safer to work on, because you can depressurize them without physically manipulating them.