Filed, deburred and polished the edges of the 10 HS-904 main ribs. Checked and adjusted the flanges for square. Fluted the ribs until straight.
Another evening of relative calm. Harry Hopkins had laid great emphasis on edge preparation in the metalworking course I took with him back in July and I was determined to get it right. I used the magnifying lamp pictured here to ensure that I was getting a good surface.In the main, it went well but there are two very narrow notches, top and bottom, separating the main part of the flange from a tab that goes under the flange of the forward spar. These lead back to a relief
hole on the actual web and they are so narrow that they are very hard to polish. I got a small file in okay but it was nearly impossible to get at them with the scotchbrite wheel. a small sanding wheel on my Dremel might have done it but I was reluctant to try. I felt I was more likely to increase rather than decrease the chances of creating a weak point where a stress tear might begin so I eased off on the filing in this area. I think the best solution would be to use a sheet of fine abrasive paper folded to give me a profile to match the notch.
I found the 1 inch Scotchbrite wheel on the die grinder invaluable for polishing the edges of the lightening holes but I used the big wheel on the bench grinder for all the rest.Were it not for the novelty of the project as a whole, this process would have become quite boring. My shoulders ached at the end of quite a long session.
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