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Steel - Both the Air Skate Legs and Castors were ~1m high. The whole rig was (roughly roughly) 16m x 2.6m x 4m (L x W x H)
SKILLS USED: Metal fabrication (cutting, grinding, turning, milling, MIG welding), pneumatics, and hydraulics
A little behind the scenes of the behind the scenes!
I worked on a project once that was roughly the size of a semi-trailer. Not only did it have to everything required for the shoot, but we also had to figure out a way to move it on the stage and between stages. Below are the two solutions that I fabricated, installed, and operated during the shoot. As with the other projects in this section the designs are not mine.
Air Skates
Once the rig was inside the stage and on set how were we going to move it around?
Every stage has parallel runs of block and tackle manual chain hoists for rigging - but what if there were lights in the way, the rig had to be rotated, or it had to move perpendicular to the runs? The stage rigging as a solution was out.
Other large equipment like cranes or telehandlers were also ruled out because they were not easy to maneuver on a busy set and could damage the set floor.
The solution that the SFX department came up with was to build Air Skates (also called air bearings) into the supports and move the large rig by hand. The idea is similar to an air hockey table, but instead of the whole table providing a cushion of air, it was only supplied by the puck.
Again this was not my design but it was my project to fabricate, install, and operate them.
Because of the fast paced nature of film projects things are commonly designed to be laser/plasma/waterjet cut with a tab and slot design to speed up fabrication.
I can't remember how many legs I fabricated but I'm led to believe it was at least 8.
The leg on the left is upside down, ready for the air skate to be attached. Each leg came with it's own reservoir to buffer any potential air supply issues.
An in-shop test of the finished and plumbed up Air Skate legs. All they are missing was a lick of Chroma Key Green paint!
Caster Wheels
Now that moving the rig on the stage was taken care of, how were we going to move the rig around the studio to each new set?
Considering the rig was the size of a large trailer it made sense to treat it like one and move it around like a semi-truck / articulated lorry.
Again this was not my design but it was my project to fabricate, install, and operate them.
First up was the attachment point to the towing vehicle. This is the underside of the mounting plate and king pin I fabricated.
An example of the drawings I followed when fabricating.
Caster wheels assembled and ready for testing (this is just an additional section that bolted to the rest of the rig). The wheels were linked together by the large bar in front and then in the back a hydraulic ram was used to steer the wheels around the tight corners of the studio.
A closeup of the nice hydraulic ram used for steering.Â
A close up of where the nice hydraulic ram used to be...
After hours one night months into the shoot, I had to move the rig across the studio. As it turns out the hydraulic ram used for steering was needed for another project... WIthout it the back of the trailer was able to swing freely and independently of the towing vehicle (not good). I took a quick measurement of the hole centers and went back to the workshop to cut and drill a scrap piece of box section to act as a placeholder to safely get the project to its destination without crabbing.
A sense of scale of the project moving around the backlot on a nice grey Summer day.
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