The shop instructions say to use the NAS bolts to temporarily assemble the center section with the spar spacer blocks. The book says they will fit tight and may require some Boelube and tapping with a mallet. Well, that was an understatement. For some reason, I have two sets of the NAS bolts and not one would actually pass through the spar bars. The threaded portion goes right in but as soon as the bolt hits the shoulder on the shank it freezes. Some Boelube and serious pounding might drive the bolts in but they might never come out. In any case, the fit is just too tight.
I have read some forums and talked to other builders about a variety of possible solutions. My solution was to use some 800 grit emery cloth and polish the NAS bolts to where they still require Boelube and some tapping but not extreme pounding. The large bolts will require the same treatment since they seem to be tighter than the 1/4" ones. I am not sure about the ramifications of removing the gold colored coating from the bolts. I suspect the coating provides some corrosion protection (at least where it isn't scraped away when installing). I plan to look around for an alternative method of protecting the bolts without adding to their diameter (wonder if a cold bluing process used by gunsmiths might work? This is going to take some careful research since these bolts are so critical.
