Step 1: Cut the angle iron pieces for the frame to length using an angle grinder. Just as when buying wood, we tried to find straight pieces of iron with no twists or bends. Conventional wisdom says “measure twice, cut once”, and this certainly holds true for cutting the iron – too long and you put the frame out of skew, too short and there won’t be enough material to drill through for fastening bolts.
Before cutting, we sanded the angle irons using a coarse grit (80) for a rough textured look to match the wheels. If you don’t have access to an angle grinder, you can use a hacksaw, which makes a cleaner cut but takes longer. Remember to sand out the burrs after cutting.
Step 2: Cut miters on all horizontal pieces of angle iron. We used a combination square to lay out the miters on the ends of all horizontal pieces so they’re on the same plane without overlap. This allows the shelves to rest flat on all four “arms” of the horizontal frame.
Step 3: Measure and mark the angle irons for holes; drill using a drill press.
When measuring to position the middle shelf, be sure to account for the thickness of the recessed shelf, as well as the thicknesses of the bottom and middle shelves. If you simply put your hole halfway up the frame, spacing between the shelves will not be equidistant.