This Instructable describes the cannon I built to disguise the fog machine I use for my pirate-themed Halloween setup. I was built primarily out of standard 2 x 4 lumber and PVC/ABS plumbing, all available at your local big box hardware store. I apologize for the lack of interim pictures, but I did this project a while ago before I discovered Instructables.
Anyway, The main purpose of the cannon was to hide the fog machine in some context that made sense within the Pirate theme we've had for the last few years. Having the fog come out the cannon as though it were firing seemed like the obvious choice.
Step 1: Designing the Plumbing
For me, most of the fun is in the planning and research. I sketched out some ideas that could be very easily built using simple 2 x 4 lumber. I then went to the local Home Depot and Lowes to see what was available in the plumbing department that would provide the right scale. Once I had all the sizes determined, I started modeling a solution. I'm an Industrial Designer (www.eikedesign.com
) so I used Solidworks to determine the plumbing method. I decided to plumb a path from the fog machine exit up thru the bottom of the cannon to exit out the front. I used a large diameter pipe for the cannon body, a smaller diameter for the fog path, and a reducer on the front of the cannon to mate the 2 and to simulate the thick wall of my cannon.
Step 2: Finalizing the Design
Here you can see a Solidworks rendering of the proposed design.
Step 3: Building the Support Structure and the Barrel
The lower support structure is pretty simple. Each layer of 2 x 4 parts is screwed and glued from below to the layer above. I added deep counter bores to keep the screw length down.
The rings on the cannon barrel were made by cutting short lengths of the main pipe, slitting them, sliding them over the main barrel, and gluing them in place. I oriented the slit gaps on the bottom where they are not visible. The end cap is a standard pipe end cap that's been cut way down in length.
To make the flare on the nozzle end, I added a thin MDF wooden ring and then used auto body compound to swipe the transition.
Step 4: Building the Wheels
The wheels were also made from standard 2 x 4 lumber. For these, I used biscuit joints with the glue to avoid the screws. I used stock closet poles for the wheel shafts with small dowels press fit into cross drilled holes in the shafts (not shown in this image, but visible in the final).
Step 5: Finishing Details
I stained all the wood, and added some black chain and some molded wood detail parts I found at Home Depot to give the cannon some fanciful decoration. I also found a molded resin pirate head in a discount bin somewhere that I believe was originally intended as a paint-it-yourself belt buckle kit. It doesn't show very well in the photo, but I painted it bronze and added it as a cast bronze emblem on the front.
In the original design, I had some simulated strapping that I was going to make from 1/8" by 1" aluminum bar. I ultimately wanted something more Disney-esque rather than historically or structurally accurate so I added some simulated bronze nails using bronze-finished round furniture tacks.
Step 6: Video Demonstration
Step 7: Conclusion
That's pretty much it. I still need to make the straps that hold the cannon barrel in place, and I still may add the strapping to the wheels after all.
I might also add a red light to the inside of the barrel at some point to indicate the cannon firing and provide some dramatic backlighting to the fog. I'd have to make a little electrical harness between the fog machine and the fog timer though to time the light and that may be over my head.
In the photo, I also added a stack of cannon balls made from styrofoam balls painted flat black (the photo is grossly overexposed), along with a barrel that I flamed and stenciled to fit the theme (It says "Gunpowder" and "Barbados").
I didn't include any specifics as I don't know what is available at your local big box store. I'm also a firm believer that you'll get more enjoyment out of coming up with your own design anyway. Hopefully, this Instructable inspires you to do just that. Thanks for looking!