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[November 23, 2005]


Today I started building. I worked on the rear spar, specifically the reinforcement bars. First I took an file and deburred all of the edges and rounded off the corners slightly. I was using a fine toothed file. This went fairly smoothly. Then I clecoed it to the rear spar to the reinforcement bar. I saw immediately that there was a slight gap where the curve of the reinforcement bar was resting on part of the radius of the rear spar. I then took the reinforcement bar and started filing with a vixen file to put a nice arc in it. I must of worked for about 30 mins filing and filing away, making little progress. I stopped doing that and used the vixen file to make nice round ends on the reinforcement bar. I then clamped my reinforcement bar to the workbench and got my electric angle grinder out. After making multiple passes at different angles to promote a round edge, I used the vixen file to make the egde more round and then a file to smooth it out further. It took a few iterations, but the angle grinder worked really well! I found that making a consistent arc in the bar was difficult with the file. When I used the angle grinder, I made a 45 degree pass a few times to knock down the metal at the edge, Then I made 4 more passes - at about 30, 60 then 15 and 75 degrees. That made a nice roundish edge. After that, I used the vixen file to round it a little more, then a file to further round off the edge.

After that, I started to do a final deburring on the edges. I broke out the drill mounted scotch brite pad and went at it for a little. I am still developing a good technique, but this really did a nice job of taking all of the filing marks out. Next I used sandpaper and really smoothed everything out. I only did one end of one reinforcement bar, as that is all that time would allow, but I think I have a good technique down for this thicker aluminum.

This is how thr reinforcement bar should be matched to the spar. Notice how there is no gap at the bottom where the spar starts to curve.


Notice the gap at the bottom...the bar needs to be filed some more to make it match perfectly.


This is how I filed the end of the spars to make a curve. I clamped the bar down near the end and proceeded to round it out using the vixen file.


The end result!

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