Now that I had a completed set of spars for the right wing I could start the main construction effort. First job was to thread the ribs onto the spars - easier said than done! The plans say to make the ribs a snug fit and they are. The only way I found to get them onto the spars was to tap the ribs an inch at a time, first along the main spar, and then along the rear spar. As the centre rib is 5ft from either end this took some time. However, after a couple of hours of gentle persuasion the ribs were in place and miraculously a wing appeared. Next lengths of 1/4" thick 1-1/4" and 1" wide spruce were cut to fit along the tops of the spars between the ribs. These were then epoxied into place to form the upper spar caps.Finally today lengths of 3/4" linen phenolic rod were cut to fit in the holes in the spar roots and epoxied into place. This material is specifically designed to provide high-strength close-tolerance bolt holes in wooden spars and is available from ACS.
