DerbyDad03 wrote:
On Saturday, February 6, 2016 at 2:38:21 PM UTC-5, Micky wrote:
On Sat, 6 Feb 2016 12:51:28 -0500, Jeff Wisnia
wrote:


When SWMBO and I were leaving home this AM (Late for where we were going
as usual.) I pulled the car out of the garage and pushed the button on
the door opener remote in the car.

We watched the door closing smoothly, but about rive inches from full
down it reversed direction and went back up. Another try produced the
same results.

We had about 8 inches of wet snow here in Red Sox Nation yesterday, so I
jumped out of the car and went looking for some snow or ice that the
door might be striking near the ground and reversing in response to
"overload."

I couldn't find spot like that. I tried adding my strength to the
opener's as the door was coming down by pushing downwards on the outside

If this would work, wouldn't it be a way to kill the neighbor boy and
make it look like an accident?


OK, I'll play along.

First, let's assume a couple of things:

1 - The downward force of a GDO might be enough to injure or even a kill
a very small child.
2 - The neighbor boy that one might want to kill is going to be older than
a very small child. I mean, the kid has to have done something one might
consider worthy of killing for, right? So, he's probably a teenager or
young adult.

All right, with those 2 assumption in play, is the downward force of a GDO,
even set at maximum downforce, enough to actually kill a teenager/young adult?



It isn't just the downforce setting, it's also the inertia of the door.
Our garage doors are wood, and weigh well over 200 pounds each, which
makes for a lot of kinetic energy when they are in motion
..

I'm scared to think of what would happen to the kid's skull if he was
lying in just the wrong spot so his head was on a concrete floor and a
moving door came down on it.

I remember the first time one of the door extension springs broke, and
it didn't have a color code on it indicating its strength. To find out
how heavy the door was I disconnected the remaining spring and used a
bathroom scale with a 2:1 wood lever over it, because the scale topped
out with the door directly on it.

I ended up buying "150 lb" springs and have had to replace them (in
pairs) maybe three or four times times in 30 years when another one broke.

And yes, I did put safety cables inside those springs when the first one
broke, something the builders didn't bother with when we had our home
built. I happened to be in the garage while a door was closing the first
time a spring broke and the noise of the spring whacking against the
ceiling and door track scared the **** out of me. That's when I learned
about the need for safety cables in extension springs.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.