Hey guys,I haven't been here for awhile, but this forum is always the bestsource for original and unconventional home and shop solutions,metalworking-related or not!I need to replace the flimsy pine front door of my condo unit. Insteadof laying out like two thousand bucks for a proper prefab securitydoor (I live in a very expensive country), I'm thinking of buildingone myself from good dense plywood, and installing a basic lock, butfor fun and erudition, reinforcing it with a home builtelectromagnetic system, with electromagnets in the doorframe, ironplates embedded in the door, and a hidden magnetic reed switch in theframe. I'd hang small magnet on my keychain, and even if someonewatched me go in, they wouldn't ever guess what I was doing!I know from my high school electricity class that wound-for-the-purpose electromagnets can be super strong but still have minimalcurrent drain. I want to power it with a with like a motorcyclebattery which would be kept up with a trickle charge from the mains.I'm thinking that there must be industrial uses for electromagnetssuited to my purpose (high turn # and resistance) and that I might getsome surplus or even new for cheap.Can anyone suggest what kind of applications would use such magnets orwhere to get them? Some kind of solenoid? Even if I bought new, I betthey could be gotten cheaply if I could find the right source.Note: For the sceptics who think I'm making work; I've been doingmajor renovations, so the tools are out, and I live in a country witha 19% national sales tax!All help appreciated!Robobass

Magnetic doorlocks are off the shelf components, but not small enough to realistically make concealed. There are some odd ball specialty oens that can be concealed, but its a pretty involved installation. They range from 300-1200 lbs of holding force. They usually integrate with a controller and power supply that uses an alarm style gell battery for backup.I'm note sure what you were hoping to do with the magnet on your keychain. Operate a magnetic reed switch to deactivate your maglock? Perhaps you were thinking of a magnetically activated hidden mechanical dead bolt? Some high end jewlery cabinets are made this way, but realistically It isn't much of a deterrant.I suppose if you could clarify the gain you hope to achieve I could point you towards some components that might work. So far everything you have mentioend is all off the shelf stuff from Securitron, or any number of other access control hardware manufacturers.I work with this sort of stuff everyday. Its not super...

DIY electromagnetic doorlocks?

May 16, 2009 21 Replies

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Don Foreman 17 years ago

Might those "manual dogs" be essentially the same function as a bolt?

That's good security.

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David Lesher 17 years ago

Yes; they are rotary, not linear. They're tabs about 1" wide, 0.25" thick and say 1" long. Rotate the thumbturn and they emerge from the door edge and fit into frame slots.

And YES, fire safety aka fail-safe is an issue.

These are sturdy doors. I'm told that in the US Embasssy bombing in 1998; there were casualities opposite the blast; i.e. behind the building. (They died from the underpressure/overpressure wave). But all the ballastic doors held up.

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