|Rear spar ready for trimming...|
The spars were purchased from Aircraft Spruce, and boy oh boy....did they cost a pretty penny...with freight shipping due to length, I forked out just over $400 for 4 pieces of 4x1! I read somewhere that spruce trees designated for aviation use are not felled, but are cut at the base and lowered to the ground with chains - to avoid microscopic fractures in the fibres. I'd feel better about the price if that was true :0)?!?
The spars were ripped to width on the table saw. Then I setup the saw blad to rip at a 6.5 deg angle to match the rib spar apertures. I marked out all the rib stations on the spars. Then marked out the tapers at the tip-end. Take your time here...the plans print is small, and very busy. I was going to mark out and cut both left and right wings together, but I felt that If I made a mistake I would then ruin 4 spars instead of 2, so I focused on the right wing only.
The butt doublers were then glued on and left overnight. I cut off the bevel at the doublers as per plan, then focused on shaping the 2 spar tips. I had initially planned to rip a 90 deg cut along the pencil line, then plane in the bevel [see markings in above pic]. However, I decided to set the saw blade on the skilsaw to the angle required, thus creating a compound angle rip in one foul swoop.
Straight edge off-set for the distance between blade & saw plate edge.