The pipe is EMT thin-wall electrical conduit. As Andrew explained, the verticle uprights are made out of 1 1/2″ EMT and the horizontal ribs are 3/4″ EMT. Couplers are used on the verticle conduits (conduit comes in 10′ lengths so one full length and pne 5′ length coupled together to make of the six 15′ verticles) and horizontal ribs are an uncut 10′. The verticle conduits are measured and marked with medium sharpie approx every 44.75″ after starting 1/2″ in from the first end. After marking, we used a milling machine as a drill press to make quick work of drilling a total of (5) 9/32″ holes in each 15′ verticle member. The hardest part was bending the 3/4″ conduit. A pattern was first drawn on the shop floor using a concrete nail and a string to get our 5′ diameter. Once bent, the 10′ conduit made up close to 2/3 (240 degrees) of a full 360 degree circle. We made very slight bends about every inch along the conduit, often removing it from the bender to match it up to our pattern. Adjustments were constantly made to keep each rib as close to the pattern (and flat) as possible. On our pattern, we found the center of our bend and then marked each rib. We then measured in 1″ from each end and marked. Because these would not easily fit in the drill press, each mark was prick-punched to leave a dimple that would keep the drill bit in the center of the mark… otherwise the drill bit would slip off the conduit when you tried to drill it. These holes have to be drilled after bending, otherwise the pipe would kink right where the middle holes were drilled. All drilled holes must be de-burred, otherwise it could put “a run in the spandex stocking” or worse, put a nasty gash in your body (as Todd found out). Because a carriage bolt has a smooth head, we used these to bolt the pipes together. A carriage bolt has a square part next to its head pn the shaft that calls for slightly larger hole to be reamed out on the outer bend of the 3/4″ pipe. Next, 1/4″ X 4″ carriage bolts are used to fasten all the pipe together. Finish by filing all sharp edges. sawyer

Thanks!