Paging the metal fabricators.

If I wanted to make a metal box that could resist being attacked by
hand tools/electric drills for up to say five minutes, would 4mm steel
(200 Brinell, 82ksi yield) be up to the job? If not, what'd be a good
choice? It'll be around 5"x4"x1", & (virtually) uncrushable due to
what'll be inside it. Weight is an issue - it needs to be as light as
possible.

The follow-up question - could the edges be bent 90 degrees & seam
welded, with the sixth side welded on the back, or is 4mm too thick for
that? I'm thinking of pro manufacturing here rather than DIY "hit it
wiv an 'ammer".

 

assume battery drill, half decent one, decent bits, or battery angle
grinder with cutting disk

tool steel would do it

generally speaking bendability and hardness are opposites, try and bend
something hard and you get stress fractures and breakage.

migh be an idea to start with something like a small house safe, and
modify as required, make sure it's a quality one though.

ideally double or triple walled

again weight might be an issue

HTH etc

 

Hmm- I've recently been using a petrol angle grinder. Fucking hell,
what a tool.

 

I think that's Bonwick's opinion of anyone who uses angle grinders...

 

Battery drill, hand tools & freezing spray are all it needs to cope
with really. The pros armed with petrol angle grinders & portable
plasma cutters aren't worth trying to defend against in this instance.

What about case hardened?

This is a prototype for something I may or may not have commercially
produced (and for which I hold a patent), so bodging an existing widget
is out.

 

It's been done - the tin of sardines I broke the pull thing off last
night resisted every opening-type tool in our kitchen for a good five
minutes. Nearly had my finger off when I did get it open too.

 

if bodging an existing one is out, at least learn from their
construction, double and triple wall safes are very tough nuts to
crack, possibly even worth buying one just to cut it up and analyse how
it's made this saving yourself x amount of development work.

having said all that, from my experiemce of the commercial world, all
you need to do is make it out of cheaper materials to a far lower
standard so it is "affordable" (eg costs a fraction of whatever is
going inside it) and give it some rufty tufty name

depends if it's designed to hold 100 x £50 notes on a regular basis,
or just a driving licence and credit card.

 

What's this for, coke stash?

 

Grimly Curmudgeon says...

He'll need room for the refrigeration unit too, and little compartments
to stop the bottles rattling.

--
Lozzo
Track pixie
GSX-R1000 K1
I haven't lost my mind, it's
backed up to a floppy disc
that's around here somewhere.

 

It's a housing - half of a thing that contains a thing that connects to
the other half of the thing. I think that makes it clear.

 

Armoured penis sheath, a case for a packet of fags or a HDD?

You mentioned case hardening. You could get it made by bending and
welding then case harden the entire thing. Still wouldn't be resistant
to an angle grinder though.

Actually, while electro-brazing steel a few years ago, I accidentally
made a drill-resistant alloy that blunted every fucking bit I put to it
for ages. Never did find out exactly what the original steel was (toecap
grade) or quite what was in the brazing rod.

You mention 5 minutes resistance; I take it this is the likely time any
thief has to get into it before the cavalry arrives.

 

What sort of cavalry would this be for the above application?

 

Tool steel is a bit brittle and therefore a bastard to fold.
If you can get it, use some "Red Diamond" plate - its South African spec
armour plate.
That'll keep the bastards out

Dave

 

http://en.wikipedia.org/wiki/Chobham_armour

 

http://www.uscav.com/

 

You'd like banger racing. They were standard issue.

 

I can just imagine Burnt doing banger racing.

 

To really make life difficult for power tools you need to have a
composite structure. An external hard shell of, say, steel with an layer
of the stuff they put in protective clothing for chainsaw use, followed
by a layer of something like ceramic.

 

if you're crafty you can defeat a lot of the power tools quite easily.

drill, all you need is a material harder than the drill, make both
inner and outer shell out of this

cutting tools, most of them are likely to be based on cutting disks,
and they are made of three "components", (abrasive, adhesive and void)
so you only need to defeat one of them, the void being the easy one,
zinc is really good at clogging up disks and even fine hacksaw blades,
do the job properly and cast the zinc in situ after first adding a high
proportion of aluminium oxides and you're 95% of the way there, just
make sure the outer shell in particular is a good enough material and
it will even defeat oxy acetylene from cutting properly, weak points
then will be door seal and hinge / locking mechanism.

strong / light / affordable

pick any two

I suspect the OP wants all three, that's usually how it goes with these
things.

 

in a Ford Pinto, presumably.