I left that up to my boilermaker , he just squared them up on each beam then when he cut out the holes for the bushes, he inserted the bushes in the holes with the shaft in place. Then he got the two walking axels in the measured out location on the floor and temporarily welded them together while he tacked in the bushes to the beams. Then it was a matter of welding them up whilst quenching the heat to stop the nylon from melting. We had all the wheels on by major welding time which gave us better access rather than flipping the assembly we just did it from underneath. Then wheeled it under the bin and levered it around till it was square and welded it in place.