Brief Description: Fabrication of Spar Attach Blocks abs Angles
The prebuilt Spar Option does not mean the spars are complete. Each Spar needs to be fitted with a Root Wing Attach Assembly and an End Wing Assembly. These are fabricated from aluminum angle extrusion material (or if you buy the Precut Angle Option the angle portion of the assembly will be supplied. However the Attach Block which is part of each assembly must be fabricated for a single solid aluminum solid block. The supplied block must be cut into 4 pieces and fitted on the Wing and Root Assemblies.
Cutting and drilling these blocks was a challenge. I am so happy the Bob (with his machine shop experience) was there to advise, demonstrate and help hold and align this process.
I tested first with a one by one block of wood. Immediately I found that the band saw blade was a little dull and would make square cuts impossible. So off to Harbor Freight for a new saw blade we went. Also while there we invested in a vice that would help us hold the pieces level and secure for the drilling process required. (More money spent that was not counted on!)
In cutting the blocks we found the use of some cutting fluid helped. Cutting a solid block requires that you not rush the saw if you want a straight cut.
Once the blocks were cut we found that because the angle materials had a bevel radius the block needed to also be beveled for a better fit.
With all the component parts made now the assemblies could be held together with the new vice and other grips and holes could be drilled and up drilled for the proper fasteners.
The holes that hold the blocks on to the angle could be drilled to the AN4 hardware size on the drill press. But the holes to attach the angles to the spar and the hole through the spar and the block that would eventually be the attach hole through the airplane frame, we felt need to be done with the Spars attached. So the Spars were aligned, clamped and attached across the garage on saw horses using the three threaded alignment holes as attach points.
