Every chain saw manual tells you it's dangerous, just as every pool owner knows a pool is dangerous. Every day you ride your motorcycle, you face danger. And every time you mow the lawn, you face life-threatening injuries.
Winding and unwinding garage door torsion springs 'is' dangerous.
On the Richard Kinch site, there is a calculation where the end result is that the force, if something goes wrong, is such that the winding bars will be thrown at greater than the speed of a bullet. An 18 inch long bullet is definitely not something you would want your body to be in the path of.
In addition, having the torsion bar suddenly spin up to 7 or 8 revolutions could cause the door to suddenly do strange things, which could startle someone and cause them to topple off the ladder.
However, given the rather minimal forces it took me to wind my quarter-inch thick torsion spring, I would think it unlikely that a winding bar would casually slip out of your grip. It could slip out of your grip, but, I would think it perhaps more likely that THE WRONG SIZE winding bar could (easily) slip out of the winding cone. Or that the right size winding bar which is not placed fully into the winding cone could slip out of the winding cone.
Those would be dangerous mistakes that Dan Musick's DIY warns against.
- He says, NEVER NEVER NEVER use a screwdriver, for example!
- He shows how to tape the winding bars, to see when they go in all the way.
- He explains how to measure 'swing', which is the fit tolerance of the bars.
- He warns to keep your head and body out of the kill zone.
- He warns against the use of flimsy ladders and of untidy work environments.
- He warns against unbolting the stationary cone before unwinding springs.
- He warns to disable the GDO so that nobody opens it from the outside while you're working on it. etc.
I suspect many (perhaps even most?) of the accidents are due to people NOT following those simple safety procedures ... which are all fully within the users' control.
There are things OUTSIDE the users' control that can go wrong.
For example, there is the remote possibility of the winding cone breaking, or of the spring breaking. Or of an earthquake happening just as you start to unwind the spring. Or of a black widow spider biting you as you wind away.
These are simply risks you have to live with.
As Richard Kinch said, it's no more dangerous than a whole bunch of other dangerous things we men do all the time.
I agree that I was very surprised how uneventful and unfrightening the entire operation was. Unwinding is clearly less stressful than winding; but even winding is on the stress level of, say, climbing a tall ladder.
The forces, while formidable if let loose, are easily that which any adult male would have no problem whatsoever with (at least for the
0.250"x36"x2"ID spring that I wound and unwound a half dozen times).At the beginning, my biggest fear was that I would forget a step; but, I had mulled the entire sequence over in my mind many times before I ever took wrench to bolt - so it was actually anti-climactic when I first wound and unwound my spring.
Even so, I was doubting myself, thinking "this is so very much easier than everyone made it out to be ... maybe I'm doing something wrong".