Okay so this explanation has been a long time coming. Red Rock is a church that loads in and out every week so we needed a way of speeding up the process while adding a dynamic lighting system to our services. These lighting road cases filled that need. Traditional road cases wouldn’t have worked because of the amount of time it would have taken to rig the lights every week, then unrig and store afterwards. A pre-hung manufactured truss was too expensive and bulky for the size of our room, not to mention heavy.
The idea was to role two 12”x12” x 10’ sticks of box truss fully loaded with lights and completely wired off our trailer, into position in the room, bolt them together and lift them onto the crank stands. Add the set pieces as needed, plug in the power feeds and the data feed and you are ready to go.
The carts needed to fit through a standard 36” wide doorframe and on our trailer. I made them 9’ long (although they really ended up at 9’1” long) so that we had almost 6” to lift them from on either side and to not take away too much rigging space for the lights near the edges. The sitting height of the truss while in the cart was important because it was also the initial lifting height of the rig. I wanted it high enough that you didn’t have to bend over with the load when lifting or returning it to the carts, but low enough that you weren’t straining to keep the load above your shoulders. Based on that I chose 4’4” off the floor as the sitting height of the bottom of the truss. This gave us enough height above the truss to rig smaller lighting fixtures to the top bar and roll them back for storage while still clearing the door of the trailer (6’1.5”).
It’s important to keep in mind that because our trailer door serves as a ramp and it is at an angle when being used as a ramp, I could not design a cart of this length at full clearance height or we would hit the ceiling because of the length and angle. I also had to add two extra casters into the middle of the design so that the cart didn’t bottom out due to the angle. For this reason among others like storage options for all our gear, I used Sketch-up to CAD (Computer Aided Drafting) everything. The ability to CAD things helps you see the potential problems before you are in the build processes. Sketch-up is free and fairly easy to learn so if you try to build something similar I would start by learning this or a similar program very well.
I made the truss compartment 2’3” deep below the sitting point of the truss primarily because of the type of lights I eventually would like to hang off of the truss. This step was crucial, because once built these carts are nearly impossible to adjust. I choose my ideal lights, which I still do not own, used their height and added in the height required for the clamps and came up with my desired depth. Above the truss I decided that 5.5” (a 2×6 board) would clear the doorway of our trailer. The 2×6 board is the backbone of what I call the “truss collars.” They slide down on top of the truss and lock the truss in place via a vertical 2×6 that slides between the truss’ V-bracing. This keeps the truss from sliding during transport. The “truss collars” are quickly attached to the frame of the cart via two hex bolts that feed through the “collar” and through the vertical supports of the cart. They are quickly tightened together via wing nuts. I chose not to put a lid on top of the rig to save money, reduce weight and because we live in a desert climate that rarely gets rain. When we do have moister we can easily throw a tarp over the rig.
The “truss compartment” would need a removable side so that the truss and subsequently the hanging lights would not have to be lifted very high to clear the sides of the case. I designed the cart so that the entire 9’ long width of one side would be on hinges, which folded down and gave easy access to the truss. 2’2” of the height of the side would fold away. This essentially leaves us only having to lift the truss six inches to clear the cart. We always line this particular side of the carts up to the side of the crank stands. Because the hinged door is so long it was made with two pieces of 7/16” plywood and reinforced with a 2×2 frame to help keep it from warping. I didn’t make both sides of the “truss compartment” hinged because the solid side adds rigidity to the overall structure of the cart.
When placed in the cart the truss is sitting on two points on either end, so the ends of the cart are well built. The truss itself sits on a horizontal 2×6 that is attached to two 2×4’s on either end that run the full height of the cart. These vertical boards are reinforced horizontally by two additional 2×4’s and overall by one solid piece of 7/16” plywood that is attached to the outside of the framework. The load is transferred through these end sections to six casters through a ¾” piece of plywood that makes up the base in two pieces. The plywood is also reinforced by 2×4’s laid on end that encompass the entire perimeter of the plywood. There are additional 2x4s spanning the perimeter 2×4’s every 2’ on-center, with a doubled section at the joint of the two pieces of ply.
Once I had figured out the “Truss compartment” and the overall structural layout of the cart I was left with a large compartment underneath that was 8’6” wide and 1’8 ¼” high with 2’1” worth of depth. It took me a while to figure out exactly what I wanted to do with this space. Up to this point we were using lots of tote crates for storing all our wiring and gear. Although the totes were labeled they were often hard to find because they could be placed anywhere and could easily blend in amongst the others, costing us valuable time. For this reason, I wanted to make specific drawers in the truss carts that would not only give gear a specific home, but would also be placed in a specific location when rolled into the room. By reducing the number of separate pieces this helped to eliminate a lot of the complications behind loading the trailer itself. I also knew that we would be purchasing some lights that would be placed on the floor for up lighting set pieces. These too would need a road case, not to mention a hazer case and a lighting console case. Knowing this, I laid out the remaining space to accommodate as many of these factors as possible.
For the majority of the remaining space a sliding drawer system made the most sense with the exception of the space where the hazer would sit. I decided to make several drawers and make them out of ¾” hardwood ply. The hardwood ply is less prone to warping, which allowed me to use the space more efficiently. All drawers were designed to be 1’11” deep from front to back and placed on 22” 100lb rated drawer slides. Here again I placed a larger hinged door that spans the full length of the cart in front of the whole section of drawers. The latched door acts as a locking mechanism to hold the drawers in place during transport. The door is placed on the opposite side of the cart from the “Truss Compartment” door so that one door would not block access to the other section. Again, I used a 2×2 framing system on the interior of this door because of the length. That’s why the depth of the drawers were reduced to 1’11.”
I laid out the space by creating a small drawer specifically designed for the size of the console I wanted with adequate space for foam to line it, and for additional wires and console lights. I then designed a long drawer for the long strip lights I wanted and again allowed room for foam lining. I wanted the drawer to be able to house up to eight of these long lights, although I intended to only own five. Below the strip light drawer I designed two smaller drawers of equal size. One is used for our smaller slim par light fixtures while the other drawer is for miscellaneous gear like gaff tape. Bellow the lighting console I designed a drawer that houses all our dmx wire. Once these set of drawers were in place the remaining space would be used as a compartment for our hazer. Therefore five drawers and one extra compartment encompassed the space of one of the carts.
For the second cart I decided to duplicate the dimensions of the lighting console drawer and the dmx drawer. The smaller drawer was again lined with foam and is used for audio gear (DI boxes, microphones, etc.) and the larger drawer houses the audio snake. I split the remaining area into three even sections, which made three large drawers. One of these drawers was designated for audio wire, another video wire/gear, and the other all power wire. Recently we have added a projector cart, which I will do a post on later that now houses most of our video gear.
To mount the drawer slides to the actual frame of the cart I placed 3/4” plywood dividers between the drawers in their laid out positions and screwed them into place from the plywood above and below. I mounted the slides to the boards first and then installed them in the carts in their designed locations. From there I took actual measurements of their real physical positions and made adjustments to the drawer’s actual dimensions as needed so that they fit perfectly when constructed. This was crucial because the drawer slides aren’t very forgiving and 1/8” makes a huge difference as to whether or not the drawers would actually slide.
We have been using these carts for nearly a year. I’ve added handles onto both ends of each cart for ease of use when steering them into place. One drawer has settled badly and gets hung up from time to time. It’s scheduled to be fixed this summer, but other then that these carts have worked out great. When the truss is bolted together and fully loaded down with six moving heads, up to nine slim pars, and up to five strip lights it can take as many as six guys to lift it into place, but we usually have less on the truss and can often get by with only four guys.
I touched on this in my Designing a Lighting Rig post, but if the school we meet in had let us hang chain motors the weight of the truss would be nearly irrelevant as their would be no need to dead lift the whole rig. So if you decide to follow a similar path please pursue chain motors if you can, even though they cost a bit more then crank stands.