On Mon, 11 Apr 2005 11:21:17 -0700, lid wrote:

I use rare earth magnets to hold steel doors open and closed, everyone else uses
hooks, doorstops and latches...because that's the way it's been done for years.

You mean like the ones you've been able to buy for Oh, maybe 30-40
years? I installed a bunch of those back in '78 or '79. The also used
electromagnetic hold-open latches on the fire doors that were tied to
the heat detectors. As soon as the temp rose all the fire doors would
close.

Just for the books, sometimes a hook or latch is better than a magnet,
they can hold against a direct pull and require a more specific action
to disengage them. Sometimes that is an advantage. Door stops also
have advantages - can a magnet hold the door open half way? Oh, don't
forget cost as well. Engineering involves a lot more than just
determining if something works.

--
"We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"

Tim Douglass

http://www.DouglassClan.com