building dry ice fog machine

[kiwitechgirl]

I was floor LX for a production of Les Mis back in 2001 and we had the biggest dry ice machine I've ever seen - we used it in Javert's Suicide to simulate the river under the bridge, which looked stunning. That would be the only place you'd want to use it - all the rest of the smoke in the show was theatrical smoke, which rises rather than rolling along the ground. Ours was custom-built for the production - by a qualified sparky - and was fairly much what has been described earlier in the thread - a big metal drum (which had been ripped out of an old rain truck from Singin' In The Rain!), 3 elements, tubing, a basket to put the ice in, and a fan, housed in a big wooden box. Ours was a bit more sophisticated in that we had a thermostat in it, so you set what temperature you wanted the water at, and then it would cycle the elements on and off, like your oven, to keep the water at that temperature. Originally it used the pump-and-showerhead method (water is drawn out of the tank by a pump, and showered over the dry ice) but that never really worked for us, so we altered the machine so that the basket could be lowered into the water (external latchable arm) and it worked perfectly. It has a control panel on the back of it (recessed so it can be covered for transport) with a fan switch, indicator lights for each of the elements, a gooseneck lamp so you can see the control panel, the thermostat display and controls, and a low water indicator light. We still use the machine (although it has had a new tank - the old one rusted out) but it was built to last, by a professional who knew what he was doing.

[laserguy216]

Ok Fellow Members, I need to know about the water sensors & over current protection... what kind do I need? and can I find them at home depot?? or ??? thanks

[eternalfire1244]

One place I visited had a dry ice fogger made out of a hot water tank. They took the top off with a saws-all and welded a basket in the top. Worked quite well and was super cheap because they got it from a local dump. They just made a rolling base and installed GFI on the power cable. All in all I think they spent about $80 in parts. A fan in the lid would have been really nice, but I don't think it ever got one. it worked well for the effect they were going for, but would need to be altered for a larger venue or to create a very rapid change.

[laserguy216]

ok things I have now are....
2-55 gallon drums one for cutting off the lid for the other drum.
a blower.... a dimmer switch for the blower.....50' of 3" dry hose..
sealed control box... 2 heating elements & thermostat.... valve for draining.. plumbers putty..wire nuts..
s...

Im off to the stor for GFCI, WIRE, BASKET, &????????????

[Les]

Originally Posted by laserguy216

ok things I have now are....
2-55 gallon drums one for cutting off the lid for the other drum.
a blower.... a dimmer switch for the blower.....50' of 3" dry hose..
sealed control box... 2 heating elements & thermostat.... valve for draining.. plumbers putty..wire nuts..
s...

Im off to the stor for GFCI, WIRE, BASKET, &????????????

Don't use a dimmer switch to control a motor.

[laserguy216]

I tested it and it works, why do you say I shouldnt???? PM me...

[renegadeblack]

Originally Posted by Les

Don't use a dimmer switch to control a motor.

I'm assuming I've got it wrong here... but... I thought that as long as its still a sine-wave it's fine.

[philhaney]

Originally Posted by Les

Don't use a dimmer switch to control a motor.

Originally Posted by laserguy216

I tested it and it works, why do you say I shouldnt???? PM me...

Originally Posted by renegadeblack

I'm assuming I've got it wrong here... but... I thought that as long as its still a sine-wave it's fine.

When you control one or more lights, the load on your dimmer switch is resistive (i.e. a big resistor, which is what they are designed for).

When you control a motor, the load on your dimmer switch is inductive (i.e. a big coil of wire). This introduces a phase component into the circuit (peak voltage and current flow don't happen at the same time like they do with a purely resistive load, even with a sine-wave). It may work for a while, but over a very-hard-to-determine-exactly period of time, the dimmer switch will burn out (as in sparks and smoke).