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.
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 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.
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.
