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First a slightly oversized (+1/4") blank is cut from angle stock.
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Dimensions are transferred from the plans to the blank using a ruler and permanent sharpie marker.
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Many of the parts need to halve the angles adjusted (either opened to greater than 90 degrees or closed to less than 90 degrees). There are many ways to do this, but I settled on the direct approach: hit it with a 4 lb hammer. I am using smooth particle board underneath the part to protect the edges from marring.
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After hitting, check the resulting bend angle against the template.
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It is easy to over bend the part, which the template shows here.
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To close the bend angle, the part is slowly squeezed in a bench vise.
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Eventually, you will have a correct, uniform bend angle on the part.
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Next, the blank is cut to shape on the band saw.
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Be sure to wax the blade before every cut to prolong the blade life.
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After the initial cutting is complete, the edges are smoothed and sanded using the belt/disc sander. I use 80 grit belts and 60 grit discs. They make short work out of the aluminum.
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Areas that can not be sanded on the belt sander are dressed using files. My favorite all around file is the 8" half round file I got from Brown Tools. Quality is superb, and it works extremely well.
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The part is then smoothed, debured, and polished on the Scotchbrite wheel. The wheel turns the edges into silk, but if you are not careful, it will take off too much metal. It is not difficult to do, but does require a bit of finesse.
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Once smoothing is complete, the part is ready for drilling holes.
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Holes are first center punched using a Harbor Freight spring-loaded center punch. Then, they are usually pilot drilled to approximately 3/32" using a #40 drill bit in the drill press.
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When the drill breaks through the back side of the aluminum, it leaves a bur that must be removed. If you back up the part with scrap wood, this bur can be reduced in size, but chances are, you will still need to dress up the hole.
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Holes are then debured using my deburing tool (an Avery #59010 Hex Adapter with #01050 cutter in a cheap cordless drill).
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Any remaining imperfections are hand polished out using medium (maroon) and fine (gray) scotchbrite pads.
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Lastly, the part is compared to the plans to verify it's accuracy or identify areas to rework/fix (worst case reject the part all together). The part is now finished and ready to prep for priming (should you choose to).
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