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| The first thing I built was the Master template/drill jig. This will serve as the absolute reference for all routing and flanging dies as well as form blocks. I used a piece of 3/4" MDF for mine. I began by cutting out and gluing the Drawing #4 full size Mylar rib drawing to the MDF Blank with some high tack spray adhesive. I then marked all key points, such as the centerline, alignment pins , hole centers and spar lines, with a center punch and cut out to the line with my band saw and final sanded with a disc sander to remove the line. This gave me a perfect representation of the wing shape.
To ensure all my holes were perpendicular to the material I planned to drill I cut 25 pieces of 7/16" .095 4130 tubing 3/4 " long. These I deburred on both ends and flattened on one side with the grinder. The flattened side will grip the epoxy and prevent the guide from turning in the MDF. They were then heat treated to prevent wear.
29/64 " holes were then drilled at each location previously marked on the MDF using a drill press to ensure all holes were perpendicular. I then mixed some West System Epoxy and thickened it with Colloidal Silica. This gives a very stiff paste that when set is as tough as steel. To prevent the epoxy from going through and gluing the blank to the work bench I applied plastic film to the back of the blank. This stuff is adhesive on one side like tape except wider. It was developed to be put down over carpet and stairs during construction to protect the carpet and wood. It is cheap and like duct tape has a million uses and is sold at any home improvement store.
I then liberally applied the epoxy mixture to each drill guide and pressed them into each hole in the MDF. Wipe off the excess and don't worry about getting a lot in the drill bushings After hardening use a 1/4 in reamer to clean them out and take the bushing to the final 1/4" id size.. The finished product works very well and is very durable. It does take a little extra time to build one like this but the end result is worth it. Every hole will be the same in every rib built and every rib will be the same.
Completed 03/04/2005. Time to complete 6.5 hours. |
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