I had understood that the WAF bolts in shear were a backup for the real attachment: The clamping action due to the bolts squeezing the two outer and inner WAF plates together. If the bolts were a sliding fit, then the WAFs would need to move to get the holding action without the clamping action. The bolts should be tightened using a torque wrench to get the proper clamping action.
Sid Wood Tri-gear KR-2 N6242 Mechanicsville, MD, USA ------------------------------ Matt Quimby wrote: >> I?vegot my wing spars aligned and attached my wing attach fittings. The >> next step, according to my plans, is to ream the inboard-to-outboard fitting holes from 3/16" to ??. This being obviously a pretty critical step to get right, I?m looking for some input on how some other folks accomplished this task successfully (or, conversely, what methods caused problems.>> I think there's been a misunderstanding somewhere. The 3/16" holes are used where #10 (3/16) bolts hold the WAFs to the spar caps on all WAFs. The only reaming that is done (and it's not always necessary) is at the WAF fitting bolt holes where inboard and outboard WAFs connect together. The reaming is to enable a bolt to fit through the hole because they are often undersize to make sure it's a very tight hole with no slop. Another part of this is that even AN bolts are not all exactly the same diameter, so the purists would buy several reamers .001" apart and shoot for perfection. Mainly you just want a round hole that's a tight fit, and a drill bit really can't get you there (their holes are somewhat triangular when drilled in thin material). More than likely the WAFs were either machined or laser cut, to the holes are already round, but perhaps slightly undersize due to coatings or burrs (laser cutting). I'd measure your bolt diameters and order a reamer from McMaster Carr that fits them. More than likely though, a plain 3/8" reamer will be "close enough". See http://www.mcmaster.com/#reamers/=ypf185 and look for the "decimal sizes" about a third of the way down. Mark Langford ML at N56ML.com http://www.n56ml.com
