Project: jseaborn     -     Entry

Dec 31, 2019 2 Sorted and prepped wood for RH spar Category: Wings
I thought it would be neat to start the new spar in the new year so I sorted through the collection of Douglas Fir that I've been keeping since my last project. My desire was to build the RH spar using this lumber. Despite having a couple hundred pounds of lumber, after measuring and careful scrutiny of my current collection, I've got to get more. Some of the lumber that I have has knots in critical locations, or grain that runs out to the edge, or not long or wide or thick enough for the spar laminates. The main spar is a made of six laminations; three on the top and three on the bottom. The laminates are 4-1/4" wide (107.8mm per the plans) and each laminate is about an inch thick (26 mm to be precise). There are three different lengths on the top laminations and 3 different lengths on the bottom laminations. To get the required length and width and thickness requires up to a 13' long section without any knots or grain runout or pitch pockets. There is an allowable amount of imperfections permitted but it's not easy to get a good section of wood.

Sometimes you discover some imperfections when you're prepping the wood. For example, there was a real nice piece about 20' long that was about 9" wide and 1-1/2" thick. It looked like it could be used for a few laminations. As it turned out, there were a couple of knots about a third and two thirds of the way down the length of it. They were not visible from one side but they are clearly visible on the other side. I don't expect that planing the board down to it's required thickness will be enough to remove those knots.

Speaking of planer, after about an hour of using the planer, it decided to make metal and chew up the board that was in it. I'm not sure where this metal came from and what the issue is but that's something I'll have to look into. A quick glance at the blades suggest that they are ok.


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