Binding of the Delrin wheels reminded me, that in my 10" kit the wheels washers and bearings came preassembled but I found the washers were too thin to allow any tightening without binding of the wheels. The seperate 5mm washers that came in the kit were about .2mm thicker, so I ended up swapping all the washers to make things work. When I talked to Colin about the problem with the washers it was like he didn't understand, and said I was tightening too much. If the bolt and nut can still spin with the fingers in the wood frame I wasn't tightening enough in my book.