Saturday 29 May 2010

29th May 2010 - Left strut attach

Work is getting in the way of building at the moment but I suppose it does pay for it. However, I did get a chance to make a bit of progress today. First job was to make the strut attach brackets for the left wing. For some reason I only made one pair originally (back in March 2008). The process for making one of these was first to bend a 9" length of 0.071" 4130 sheet into a U section using the bending brake - this takes considerable force! The legs of the U were originally about 1" long to give the brake a reasonable area to work on. Then the legs of the "U" were shortened to final size using the bandsaw. A smaller section of sheet material was then bent to fit snugly inside the end of the length and welded into place. This was repeated for the second bracket. Then a 3/8" hole was drilled in the end of each bracket. They were then bolted together and the second two holes match drilled through both brackets to ensure that the hole spacing was identical in each. Finally, the top of each bracket was curved where it fits against the outer wing rib.
Next job was to laminate 4 pieces of 1/16" birch 3-ply into the first of the 1/4" 12-ply plates which provide additional strengthening where the brackets bolt to the spar. This is done with epoxy without any filler and clamped tightly whilst the glue sets. The result is a plate considerably stronger than a commercial 1/4" material which would usually be 5-ply.
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