How to cut a wire from an arduino

[Fr34k]

I'm making an escape room and I want to make a box fall when an ultra sonic sensor senses movement and I want the box to fall with the wire that is holding it cut how can I cut the wire

[technix]

Solenoid-controlled scissor?

[Freelander]

I'm making an escape room and I want to make a box fall when an ultra sonic sensor senses movement and I want the box to fall with the wire that is holding it cut how can I cut the wire

Solenoid,
Heat,
Definitely the solenoid controlled scissors
Semtex,
High velocity rifle round,
RPG,
SLAM,
Samuraii sword with micro gas turbine..

One must ask..  is an 'escape room' and why do you want a 'box' to fall, and what weight is it. ?

Why not just put a bucket on top of the door like we did 50 years ago ? - always worked (at least once)

If you get some photographic flash powder, a small tin (for example - a .22 air rifle pellet tin) - add two feedthrough caps to the lid, a bit of fuse wire inside between the cap inners, and add some strontium nitrate (screw lid on tight and connect bell wire to other end of FT caps..... all you need to do is put a reasonably small current on the bell wire and it will certainly bring your box down. It is very cheap to make and we have successfully used it to make a reasonably sized crater from a rabbit hole.  I recommend at least 10 mtrs between yourself and the 'tin' of boom boom...
 

[jaycee]

Spring loaded rod with a sharp edge ground on end of it, held under compression by a latch pin. Solenoid to disengage the latch. Have the rod fire at a plate with your string/wire on it, so that the impact of the sharp end of the rod severs the wire.

[technix]

Or you can use fusable wires, discharge a big cap into it to break the wire.

[TK]

Answer will depend on the type of wire you are using to hold the box (Wire gauge, or box weight just to image what type of wire will be required to hold it)

[james_s]

A servo operating a pair of scissors or something similar seems like the easiest route. Does the wire have to actually be cut, or could you have the end loop around a pin that is pulled back by a servo or solenoid to release it?

[ez24]

Will the box be empty or full of bricks?  ie what is the weight and size of the box? 

I think the difference is between "ha ha ha"  or RIP

How about an electrified net that falls down like in Big Bang Theory?

[rstofer]

The wire doesn't need to support the load, it only has to hold the catch mechanism that holds the load.
Solder would probably work well if there is a battery battery to melt it.

[jeroen79]

The problem with cutting the wire is that you ahve to replace it every time when resetting the room.

How about a springloaded clamp to hold the wire and a solenoid to pull against the spring to open the clamp.
Saves the wire and only consumes power when opening.

[rstofer]

Ah...

You can take a clothespin, wrap each jaw with copper or aluminum foil, make the connections as Normally Open.  You then put a small piece of insulator between the jaws and this is physically connected to the trip wire.   When the wire is pulled, the insulator pulls out and the circuit goes closed.

[phil from seattle]

Do you need to cut the wire? There are plenty of ways to release a wire without cutting. I'd use a solenoid to pull a pin which holds the wire.

[DBecker]

NASA Standard Initiator

They are very well characterized and understood devices.

I'm half kidding.  But only half.

[sleemanj]

One must ask..  is an 'escape room' and why do you want a 'box' to fall, and what weight is it. ?

https://en.wikipedia.org/wiki/Escape_room

Have become quite popular in the last couple years.

[westfw]

Spectra is a polymer that is very strong, but with a low melting point.  I always figured this sort of thing would involve a length of spectra, a piece of nichrome wire, and a relatively high-current switch.

[CopperCone]

a surefire way to do this would be to discharge a supercap into some steel. The stuff that holds paintings would work. You just unravel some steel cable, then connect a strand to some copper leadwires (use a western union splice for the junction) and put the hanger in the middle of the steel wire. You can buy it at a hardware store real cheap, and you will have a ton of it for different escape room experiences. You could also use a lithium battery with high current.

I would not recommend pyrotechnics due to legal issues. This could result in a drop of molten steel falling on someone though.

I doubt a solenoid is as reliable as this method.

Personally I find escape rooms a bit creepy, perhaps due to certain movies. I believe the "Cube" series takes them to a logical extreme.