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Hey, everyone. I thought I'd share a project I've been working on for the past few months. For years (literally) I've wanted to build a 3-axis skull, and this last Halloween season I finally started to work on the project. Here you can see my third attempt in motion on my workbench:
As you can see briefly in the video (when it shows the plate without the skull), it's based on halloweenbob's design.
V1
My first attempt at the project was in the months leading up to Halloween. I dove head first into the project without a ton of planning. I knew there was a lot of knowledge I'd have to obtain by just doing. I also was under some tight time constraints if I wanted the prop working for the 2014 season.
I created the clear plexiglass plate by hand in my garage, using mostly a plunge router:
I made a few mistakes along the way though. The biggest mistake I made was using too narrow of a rod. The rod was too narrow to really handle the stress I was putting on it, and the animatronic ended up only being active for one night of the haunt. For the one night that it was active, I had a programming bug that prevented the character from being fully animated. And I was out of time -- when I had any chance of finally rectifying these issues the season was over.
V2
After Halloween, I went back to the drawing board. I realized that my attempts at cutting the plexiglass in my garage were not precise enough. The slop in the design meant that I couldn't get the servos exactly where I wanted, they wouldn't be held in place as tightly as I had hoped, and overall the entire system just lacked the precision I needed for the stress I was putting the animatronic under. It was time to pull out the big guns. I contracted a laser cutter:
The laser cutter milled my second design with sub-millimeter precision into 0.25" plexi. What a world of difference! The plate was gorgeous.
Designing purely in 2D and then imagining how it would assemble in 3D is a tricky thing to get right the first time though. I missed some measurements, misjudged how wide the laser kerf would be, and overlooked a few other issues in the design. The plate was good for taking measurements off of for refining the design, but it couldn't actually be used in an animatronic.
V3
And that brings us to the third design, the one in the video. After some revisions to the design I sent it off to the laser cutter again, and received this some time later:
The design still isn't perfect, but it's entirely usable (as seen in the video above.) The main rod comes in at a hefty 3/8" thick. The skull is a standard Lindberg skull. The four servos are being controlled by an Arduino with an Adafruit servo board. I do software development for a living, so running this project with an Arduino was just the natural choice.
The project is still far from complete. The software still needs a lot of refinement, and I've got some some other cool features in mind that I'll post as they progress.
As you can see briefly in the video (when it shows the plate without the skull), it's based on halloweenbob's design.
V1
My first attempt at the project was in the months leading up to Halloween. I dove head first into the project without a ton of planning. I knew there was a lot of knowledge I'd have to obtain by just doing. I also was under some tight time constraints if I wanted the prop working for the 2014 season.
I created the clear plexiglass plate by hand in my garage, using mostly a plunge router:

I made a few mistakes along the way though. The biggest mistake I made was using too narrow of a rod. The rod was too narrow to really handle the stress I was putting on it, and the animatronic ended up only being active for one night of the haunt. For the one night that it was active, I had a programming bug that prevented the character from being fully animated. And I was out of time -- when I had any chance of finally rectifying these issues the season was over.
V2
After Halloween, I went back to the drawing board. I realized that my attempts at cutting the plexiglass in my garage were not precise enough. The slop in the design meant that I couldn't get the servos exactly where I wanted, they wouldn't be held in place as tightly as I had hoped, and overall the entire system just lacked the precision I needed for the stress I was putting the animatronic under. It was time to pull out the big guns. I contracted a laser cutter:

The laser cutter milled my second design with sub-millimeter precision into 0.25" plexi. What a world of difference! The plate was gorgeous.
Designing purely in 2D and then imagining how it would assemble in 3D is a tricky thing to get right the first time though. I missed some measurements, misjudged how wide the laser kerf would be, and overlooked a few other issues in the design. The plate was good for taking measurements off of for refining the design, but it couldn't actually be used in an animatronic.
V3
And that brings us to the third design, the one in the video. After some revisions to the design I sent it off to the laser cutter again, and received this some time later:

The design still isn't perfect, but it's entirely usable (as seen in the video above.) The main rod comes in at a hefty 3/8" thick. The skull is a standard Lindberg skull. The four servos are being controlled by an Arduino with an Adafruit servo board. I do software development for a living, so running this project with an Arduino was just the natural choice.
The project is still far from complete. The software still needs a lot of refinement, and I've got some some other cool features in mind that I'll post as they progress.