Re: Safe Room Door Lock

[Robert L Bass <sales@xxxxxxxxxxxxxxxxxxxxx>]

On Wed, 8 Feb 2006 09:58:00 -0700, "Crash Gordon"
<webmaster@xxxxxxxxxxxxxxxxxxxxx> wrote:

> Yes saw the movie.
>
> It's really not intended to be a people safe-room although it could sorta be
> one...more of an informal secured room in a snow-bird house for him to hide
> large paintings and shit like that.
>
> I doubt though that a screwdriver could pry opened (towards you) a 600lb mag
> lock...I've tried blasting against one that opened away and couldn't do it
> with my massive super strength :-)

I forced a 600-lb lock open with my shoulder once and I'm only of
average strength -- not exactly a weight lifter.  :^)   It really
wasn't all that tough.  They're not intended to keep bad guys out
-- more for limiting movement of personnel.  If there's a wall or
other rigid, parallel structure nearby, a strong man could open
the door using leg pressure.  It's surprising the amount of
pressure even an average adult can deliver in a leg press.

Consider the leverage of a 12" long screwdriver with 1/2"
inserted into the space between the door and the frame.  There's
a 23/1  mechanical advantage.  The thief only has to apply about
30-35 lbs of force.  Note: If it were linear motion the figure
would be just over 26 pounds, but the screwdriver is describing a
circular arc so the required force in a tangential direction
increases somewhat.

If the door opens away from the lock it's even easier -- take a
run and hit it with your shoulder.  I weigh just over 200 pounds.
At a 15 mph sprint that's more than enough force to pop a 600-lb
lock.  With a 1200 pound lock it would be significantly harder to
pop.  If you use an 1800 pound lock the required force would
destroy the door before the magnet would give way.  :^)

The difference in cost between a 600 and a 1200 or 1800 pound
lock isn't all that much.  You might want to explain the options
and let the client decide what he wants to spend.  Most folks
will part with a few extra dollars if they can see a significant
advantage in the hardware.

--

Regards,
Robert L Bass

Bass Burglar Alarms
The Online DIY Store
http://www.BassBurglarAlarms.com