There comes a time in everyone's life where they think to themselves: "I really need a giant vortex cannon." No? Just me? Well that's okay, I'll show you in case the mood ever strikes.
Now, I've embellished this one quite a bit. If you just want the cannon itself, you can just cut out the hole and skip to the sewing/bungee part.
You'll need a few supplies to build this:
- A 32 Gallon garbage can. Preferably not used and soiled (gross). The "Brute" ones seem to be well suited to this.
- 1 Sheet of 3/4" plywood. Paint grade is fine. I went with "blondewood" ply from the blue store.
- 1 2x4x8
- 1 length of 1/2"-13 threaded rod
- 1 length of 1" flat bar steel or aluminum (just for looks, completely optional)
- 2 3" 1/2"-13 hex head bolts
- 8 1/2" washers
- 4 1/2"-13 nuts
- 2 1/2"-13 wing nuts
- 1 box of 1 1/4" construction screws. Not drywall screws - they're too brittle.
- 14 small washers to use with those construction screws.
- 2 yards of ripstop nylon
- about 16 inches of nylon webbing
- Approximately 8 feet of bungee/elastic cord.
- 8+ foot cam strap (like you would use to tie down kayaks or equipment on a trailer. A ratchet strap would work but is overkill.)
All of my fusion 3D files I used are attached for reference.
A few disclaimers:
I used a 3d printer for the bushings, but you could probably make this work without them by using wood spacers and extra washers, and just smaller holes in the wheels.
I also used a large cnc router that few people likely have access to. You could draw plans on craft paper use spray adhesive to attach it to your plywood, and cut it all out with a jigsaw if you're determined.
Step 1: The Main Axle.
The first thing we'll want to do is trim the part of the 2x4x8 we don't need off, but leave the rest as one piece. Leave 55" available to use.
Using a handheld router, set your guide or fence so your cut is dead center on your 2x4. Using a 1/2" half round bit, cut a 1/4" deep channel the full length of the 2x4. You could also make a 1/4" deep and 1/2" wide dado cut with a table saw or even circular saw with a guide, but the router with the right bit is a much cleaner and easier solution.
Cut the section of 2x4 in half - two 27 1/2" sections. center the threaded rod in it, glue and sandwich the two 2x4's together. Clamp it and let it dry for a couple hours.
Cut a 20" piece off of the remaining unused 2x4. This will become a step for the rear and will add some strength to the cart.
Make some straps with the flat bar to give it an authentic look. Use a torch and vise to make the bends easier. Affix it with a few holes drilled and some framing nails. Torch the whole thing to raise the grain and give it a dark, weathered appearance.
Step 2: CNC and 3D Printing Work
While you're responsible for your slicer and tool paths, all the .f3d files are attached to this for your use.
I cut this all out of 3/4" "Blondewood" plywood from the blue store. Both the complete cannon and flattened files are available. It all fits on a single 4x8 sheet of plywood easily. Parts were seperated from their tabs with a chisel and mallet, any excess/tabs trimmed with a flush trim bit on a handheld router, and all the edges were sanded smooth.
As for the bushings - I printed them with PLA at 60% infill on an ultimaker 2. If I did it again, I'd probably use ABS and with 1mm thick walls. I did have to ream out the holes with a drill and deburr the bolt holes to get everything to fit. The reason for the silly infill is that these need to stand up to some abuse. If kids are going to play with this, you know it's going to get beat up.
"But I don't have a giant CNC router or 3D printer!"
I don't either. I joined a local hackerspace that has these tools. If you don't have a makerspace or hackerspace near you that can help, there are alternatives. All of this can be hand drawn on paper templates and cut with a jigsaw. It would be time consuming, but it's possible. The bushings can be made with some scraps, glue and a hole saw or even just stacking up some extra washers, and using smaller holes in the cart, wheels and cannon mount.
Step 3: Prepping the Garbage Can.
This one is pretty easy. The "Brute" garbage can has a perfect sized ring in the bottom normally designed to attach to a wheeled cart. I drilled a hole near the edge of that ring, and we used the handheld router with a flush trim bit to cut out that ring perfectly. You could of course do this with a jigsaw, reciprocating saw or even a keyhole saw, but the flush trim bit on a router is the best way to go by far here.
Step 4: Building the Cart!
Start with affixing the rear plate with wood glue and either screws or brad nails as shown.
Glue and clamp the rear "step" on top of the plate. This 2x4 piece should fit exactly between the side pieces. Two screws should be put in through the sides and into the 2x4 on each side.
Up front, get some glue into the notches for the axle. Rest it on the axle. I used a couple brads driven diagonally to hold it in place, but this wasn't very effective. There should be 20" inches between the sides up front, and the axle should be centered.
Attach the gussets to the rear of the axle and flush up against the sides as shown. glue on the back and side of each gusset where it meets the axle and side wouldn't be a bad idea. Two screws attach it to the axle, and two more on each side to the side pieces, as shown. Use a speed square as a guide to mark the area where your screws go.
For the cannon mount, a 1/2" hole needs to be drilled in the center of each of the small side plates. glue and screw these small plates to the ends of each of the crescent parts. This won't be very strong now, but it will be firmed up once it's attached to the cannon itself.
Optional: Use a torch to flame the whole cart and all your wooden pieces for a weathered look.
Note - a brad nailer goes a long way with a larger project like this for efficiency, but isn't needed. Clamps and time will work just as well for your glue joints.
Step 5: Attaching the Cannon Mount.
With the cannon mount assembled, lay it on the garbage can at the point you want it to pivot at. Trace two lines with a permanent marker from the same side of both stretchers, this is where we're going to drill our holes for mounting.
Because we're not only drilling into the edge of plywood, where it's somewhat weak, but also this is holding a moving part - drill 7 evenly spaced holes along each of your traced lines.
Using 1 1/4" construction screws with washers screw the mount onto the garbage can. You can use some CA glue or epoxy to help hold the mount if needed, but once the first screw is in, the rest is pretty easy.
Step 6: Preparing the Baffle.
**Note: After about 300 shots, the baffle started to tear from where the nylon webbing was sewed on. I will be repairing this by sewing in a canvas circular patch in the middle of the baffle, then attaching the webbing to that instead. The ripstop was just not up to the task of getting abused for hours.**
I've done this the fancy way with some sewing work. You could certainly get creative with zip ties and gaff tape here, but I suggest sewing if you can.
I recommend using a heavier denim or upholstery thread, but with an all-purpose needle in your machine.
Cut a 48" diameter circle out of the ripstop. Pin or clip and fold the outer inch and a half back over itself to make a sleeve, where we'll thread the cam strap through. Sew the sleeve up. The fabric will fold over itself at times and ripple a little. It has to work - not look pretty. The sewn in side will be hidden anyways.
Cut a small part out where the strap can be threaded through and the buckle for it can hang out.
Cut an 8 inch long piece of nylon webbing, a 3 inch long piece, and four 1 inch long pieces.
Mark the center point on the fabric. the longer 8" strap will be our handle. Sew this to the side the outer edge isn't folded over and sewn on so your seam remains hidden. I recommend sewing the 1" square of nylon webbing on the other side of your stitch to prevent tear out. This gives your thread something much more substantial to hold onto than just the ripstop nylon. I did experience minor tearing before I did this. Stitch a square on where it mounts and few zig zags. You really can't have too much stitching on this part, so have at it. See the video for some examples.
Do the same on the opposing side with the 3" piece and the 2 one inch squares. This is where our bungee will thread through, so you want it 90 degrees perpendicular to the handle.
Thread the cam strap through - a wire coathanger or similar would be helpful here.
Tie your bungee to one handle of the garbage can. If you have the same one as me, there's some conveniently placed holes in the handles that you can thread it through.
Thread the bungee through the smaller nylon webbing loop you made in the baffle. Leave the other end untied for now.
push the whole baffle through the ring you cut in the end of the cannon. Pull it out the other side, and use the cam strap to secure it around the outer lip of the can.
Pull the bungee somewhat taught, and tie it into the other handle as shown. You've got yourself a working cannon now.
Step 7: A Few Extra Touches...
I used an old 700C bike inner tube as a "tire" around the wheels. Not to protect the ground, but to keep the plywood edges from blowing out. I secured it with some staples.
Some scrap wood blocks and pulleys were used to reduce the abrasion on the bungee and it makes it easier to pull back.
A gopro-mount-compatible crosshair was printed just for fun.
Step 8: Final Assembly.
Mark the length of the threaded rod needed to install the wheel, bushings, 2 washers, nut and wing nut. Leave a little extra, and cut the rest off with a hack saw or grinder. Clean up the sharp edges.
Attach the wheels with a washer, then the wheel with bushing, washer, nut and wing nut in that order.
Attach the cannon with the bushing and bolt, washer, through the mount, another washer, and a nut.
You've got yourself a cannon!
Step 9: Fire!
Have some fun! Ruin some hairdos. Fill with fog machine smoke and make giant smoke rings that go for 50 feet!
Thanks for sticking along and feel free to comment with any suggestions or questions. Always happy to help.
Second Prize in the
Make it Move Contest