Security screws

[ven]

I might be asked to make a new keyhole escutcheon (surround) to be fixed to the outside of a church door.
The o.d.would be about 30mm or so, a circular steel plate say 5mm thick with a pretty edge and the key shape in the centre.
The steel plate could be weathered i.e. rusted by soaking in Coke (anything quicker?) but I wonder about making the two fixing screws, round head or countersunk, burglar-proof.
I know that one-way wood screws could be bought but where from? i wouldn't want stainless steel ones because they wouldn't 'weather'.
Perhaps ordinary steel wood screws with the anti-clock side of the slot filed off?
Thanks for the replies!

[vtsteam]

Well, best would be screwing it on from inside. Usually there's a couple of pillar shaped bosses on the inside of the escutcheon that are tapped for screws. Screws extend from the inside into that. You could braze a couple of pieces of rod to the inside of the escutcheon plate, and tap them to do the same thing. Or if the escutcheon is thick enough,you could tap it for screws. It might have to be inset in the door a little for that.

[awemawson]

You don't reveal where you are in the galaxy, but I have a few boxes of security 'one way only' screws, you'd be welcome to a couple for the postage if it is geographically sensible.

HOWEVER: they would look naff in my opinion in this situation - the one way feature is achieved by 'camming' the drive slot, so one side has a vertical face and the other a ramp - on a Church door maybe rather ugly.

Why not weld / braze or what ever a pair of studs to the rear that penetrate the door and have nuts on the inside, so fixing is invisible ?

[Fergus OMore]

Many years ago, I designed a set of tamper proof screws that would protect electric meters from being illegally tampered.

Basically,once inserted and over tightened, the screw head sheared off leaving a fairly smooth surface.

I suspect that Screwfix has something similar now.

Nothing new in all this, it was the way that things like sea mines and such were disabled from being rendered harmless by bomb disposal teams.

One of the techniques to fool this is still on the British Secret list.

If you want to rust something- washing soda is the thing. My father was a sapper in the Royal Engineers

And the preacher for next week's service will be nailed to the church door at the end of this service.

Norman

[Arbalist]

I used stainless steel screws on an old house number but used copper paint on them to look a bit better. Looked very nice against the Teak I thought. Not tamper proof though.

[sparky961]

I haven't tried this, so do a test on something that doesn't matter first...

Fasten it using your favourite mild steel fastener with either a Philips (square) or hex drive head.  After doing it up nice and tight, drill out the drive pocket just slightly larger than the circumscribed circle so everything cleans up.

Think of it as purposely and thouroughly stripping the head of the fastener.  It should end up looking a bit like a rivet when you're done.

[sparky961]

.... of course, depending on the desired level of security, a hammer and cold chisel or a cordless drill could easily defeat your efforts.

I suppose this is true of anything called "security" though.  If someone wants "it" or wants "in", it's just a question of how long it takes and how likely you are to be found out.

[vtsteam]

I'd suggest that on an exterior wooden door that, at least, screws can be tightened in the future, as things tend to go loose with changes in humidity.

Under higher humidity the wood swells under the plate but being bolted stationary, the wood surface gets compressed slightly. Then when humidity is low, the inner wood shrinks again pulling the crushed fibers away from the plate. This doesn't usually happen all at one go, but over time it will loosen.

So being able to tighten the screws is important. And if there is ever need to remove the plate, it's a lot easier if the conventional practice of screwing it on from the insde is followed.

[ven]

Thanks very much for the suggestions.
I had forgotten all about shear screws, if that is what they are called.
Screwing from the inside into bosses seems to be about the best, as it would allow adjustments and removal if necessary.
My father was also a Royal Engineer and told me lots of things, but not about washing soda!
Ted, in Lincs

[steampunkpete]

Shear screws / bolts and one-way fixings are OK, but as has been pointed out one is b******r if maintenance is needed. The way I would do it would be hardened screws or bolts right through the door and nyloc nuts on the inside. Mr. Vandal can then try and undo the bolts as much as he likes, but with no spanner on the inside the bolts just go round and round.

However, Mr. Burgular is unlikely to spend a lot of time trying to nick an escutcheon, and Mr. Vandal probably isn't either - so is the engineering solution in proportion to the risk? Damn great clout nails have successfully secured church door furniture in place for centuries after all.

[Fergus OMore]

My father was also a Royal Engineer and told me lots of things, but not about washing soda!
Ted, in Lincs

Apologies but it has been 65 years since I passed 'Alexandra Palace or Ally Pally' and its old rather sinister function in a forgotten world.
So what about a bit of fun- and say 'Heinkel rivets'? I think that your Dad and mine might have enjoyed such things.

Happy VE Day +70

Norman