The other day I posted about some goggles I'd made in rapid prototype fashion for a Mad Max-ish character costume for the local Halloween parade. That design came to mind while I was working on a slightly bigger prop, a Gatling-style heavy gun.
Many of my projects start in Sketchup, regardless of the intended fabrication method, because I've gotten used to the ability to size parts and check interference visually ahead of time rather than by experience halfway through a build. I thought something imposing but lightweight would be a good idea for marching in a parade; last year's 11-foot-wide articulated wings (a post for another day) proved logistically difficult so this year, I wanted to stay a little more compact.
An early sketch:
The overall look was sort of self-determining; I wanted a rotating set of barrels with sort of standard proportions. PVC pipe seemed a good choice for barrel material because it's light, you can glue it with CA glue, and it comes in standard sizes. I figured I could use PVC couplers, cut into thin rings, as retainers for the barrels since they're pre-sized to fit snugly on the outside diameter of the pipes.
The "disc" that holds the barrels would be 3D printed, easy enough, and I could mount 608-type skate bearings to give smooth rotation around a 1" dowel center-shaft. I could have gotten away with any sort of bearing, or teflon tape, or really nothing at all probably, but I have like a hundred 608 bearings in a bag so I tend to use them any time I can.
It occurred to me that I could mount a salvaged screw gun ($5 from Goodwill) as a combination handle/drive system and actually have the barrels spin in powered fashion. Yup:
So I printed the disc parts on our large-format printer (12" cubed, home built FDM printer, that's a whole other article) and they came out okay. Certainly good enough for light use, and they'll look fine under paint:
I knocked together a frame out of scrap wood from the wood shop, and bent some unnecessarily burly aluminum bar as a front handle.
The whole deal was primered in flat black, and then I repainted some areas in silver and then hit them with "grime" paint as described in the post about the goggles.
I made a stencil from a cartoonish skull-and-crossbones logo I found online and painted my kill-count on the side of the housing:
I'll post a video soon showing the action. In an effort not to get mistaken for a person carrying an actual heavy gun in a crowd of people, I scrapped the plan to have sound effects and super-bright LEDs in the barrels firing in sequence. That said, the movement of the barrels alone is pretty satisfying.
I love Halloween.
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