Now that I had something to store the dry ice in after I bought it, I was free to start building the actual fog machine. After doing some research, I learned that if you add dry ice to hot water, the extreme cold from the ice will condense the water vapor (steam) into a cloud, thus creating fog. My original plan was to build a plywood box, cut a hole in the front of it, put a fan in front of that, then put a pot on a hot plate under it, and dump the dry ice into that. After some more thinking (and a picture I saw online) I modified the plan. I borrowed a large soup pot from my church kitchen (it holds at least 16 quarts) and I decided that instead of enclosing it inside a large box to catch the fog, I would mount the fan and hose onto a piece of plywood that I could place on top of the pot like a lid.
The first step was to make the fan. There was a time when I had lots of little motors lying around, but they all managed to disappear now that I actually needed one. I found this one on my desk. I forget what it came out of, but it was intended for an airplane I was going to make but never got around to (maybe I will this summer...). The propeller came from a rubber band powered balsa wood airplane kit that I acquired, played with and broke.
The motor, unfortunately, just didn't have the power I needed it to have. It also had a problem, in that it didn't like to start. I went hunting for another one, and eventually found an rechargable razor that my aunt got as a free gift from somewhere. She gave it to me for some reason, and it's sat on my shelf since. (it normally has a guard over the blades on the end... that's why it looks weird)
I opened it up and pulled the motor out of it. The skinny blue thing is the rechargable battery, and the rectangular blue thing with the white diamond is the power transformer. The motor is the brass colored rectangle at the top. The thing on the wires hanging from the bottom is where the power cord plugs in.
The hole in the propeller was too small for the shaft of the
motor, so I got out my drill and made it a little bigger.
Perfect!
Not so perfect, actually. There was something wrong with that motor too, or I broke it. I'm not sure which. It worked the first few times, then stopped working, and I couldn't make it start again. So I took a break from that problem and worked on the hose assembly.
I bought an 8' dryer hose from the hardware store, and attached a cardboard funnel to the end of it. My plan was to mount the fan inside of this, then attach it to the plywood base over a hole that I would cut. When the ice made fog in the pot, this would suck it out, and blow it through the hose to wherever I needed it.
If you haven't noticed, I tend to stop taking pictures when I get frustrated with whatever I'm working on. I ended up finding a motor in an old Erector set that I got when I was really little. The propeller came from a little gas powered model airplane engine that I bought from a yard sale many many years ago and never managed to get running. By some miracle, the propeller fit perfectly onto the motor shaft. I added a drop of hot glue to hold it on, just in case. I took some pieces of fence wire (leftover from the elephant project, actually)
This is it all put together. You can see one of the two holes I cut in the plywood. The visible one is the vent. The second one is under the intake hood.
