Well here we go! The first job is to fabricate the W-00009A & B Wing Box J-Channels. This is accomplished by cutting them to length, clamping to the spars, and then match drilling … in other words, you are simply using the spar holes as a template to create the holes in the J-Channel, which is used later on. Once this is realised, it all makes sense! However, as always there is a gotcha. The W-00009A’s are longer than the W-00009B’s, and the raw material comes in 8ft and 6ft lengths. It’s tempting to cut the A’s from the 8ft lengths, and the B’s from the 6ft lengths … DON’T. Use 4 x 8ft lengths for the A’s, and cut the B’s from the remaining two 8ft lengths. That way you will have enough J-Channel left to make the W-00008-L/R’s on page 17-03 (ie 4 x 6ft lengths)!! Thank you to Shaun, a RV14 builder in the US for this tip.
The spars have to be shimmed along their length so they are straight prior to match drilling. They do flex quite a bit at this stage.
Cutting to size
I clamped a tape measure to the end of the J-Channels, then checked the 2″ mark with a Caliper Gauge to ensure correct length measurement.
I cut the J-Channel slightly oversize with a Dremel Disc Cutter.
Then sanded to an accurate length with the belt sander, having checked the table was perpendicular in all planes.
The J-Channel has to be postioned on the spar, with 1/16″ sitting proud. Happily a rivet gauge came in useful, since it was exactly 1/16″ thick.
The J-Channel is clecoed as holes are match drilled. The spar lower flange has several holes which are NOT match drilled due to the inspection access panel nutplate positions. These J-Channels are flipped through 180º and clecoed to the top flange.
The manual says “roll through 180º”. A bit ambiguous until you understand what you are trying to achieve. It’s just a method to complete the match drilling using the top flange which does not have the access plate nutplates. Hence roll the J-Channel “like a sausage on a BBQ” as in the picture above to get the job done.
The overlap causes a bit of an issue. This is because the J-Channel profile varies slightly along their length. Van’s basically say do your best to make the channels snug on the overlap. In practice, some are very good, others not quite as accurate. Thinking about their future use, I don’t think it’s a problem to file the edges to fit, which is what I did. Time will tell I guess?