Lee just for what little it's worth I built one of these a year or so ago and don't think much of the method of jigging. If the wood is soft the structure is pretty light to be able to work on and hold any trueness on the rods. I would and did rather jig with blocks from the leading and trailing edge to solidly hold them straight and parallel throughout the building. Sheet the top, then turn over and re-jig to sheet the other side. Pretty hard to build in warps that way.