My Wing Rib Jig

MY WING RIB JIG:

My jig is made up of two 3/8" plywood 70" x 10" pieces glued (Elmer’s wood glue) together to form a rigid base. I just glued the pieces together while they lay on the garage floor. On top of this using 3M spray glue I attached the wing rib drawing that I plotted from the dimensions on the plans. I did not use the full size wing rib drawing supplied with the plans because it did not match the measurements from the plans (advice from a bunch of builders). Do not use Elmer’s glue to glue the wing rib drawing down. It will cause the paper to stretch, warp and have wrinkles. I should have known better. But, on the bright side, the second time I plotted the wing rib it only took me half the time (about an hour). When laying the paper on the plywood base, tape one end around the plywood. This way you can pull the pattern tight while it is in the air and lay it down smooth. With 3M glue you only get one chance. On top of this I have a sheet of 1/4" clear Plexiglas held down by screws (as suggested by Steve Eldredge). Using 3/8" Plexiglas I cut out 1/2" x 1/2" blocks then glued (special glue for Plexiglas) the blocks along the rib outline. I cut out spacers for the spars from this material also. It takes fewer blocks to hold the shape than you think, I have way too many on my jig, but it works. I initially use these non-moveable blocks to hold everything, but have since removed some of them so I could get the pieces to slide in with out scraping off the glue. The glue will not stick to the Plexiglas and I can pop my wing rib out with out hurting the jig or rib. (Cost about 15 dollars and a 1/2-day to build, including picking up the materials)

When building the ribs I tried using staples to hold the 1/16" plywood gussets on, but I did not like the way it looked after I removed the staples. I’m too cheap to buy a bunch of clamps so here is what I am doing. I glue the rib together without the plywood gussets. Let it dry for about 12 hours, and then I carefully remove it from the jig. With it out of the jig, I glue on the plywood on one side of the rib. To hold the plywood while it is drying, I use "Large Binder clips" that I purchased at the local office supply. They have a 1" capacity and are CHEAP compared to real clamps (5 dollars for 12 binder clips). They work great with the T-88 epoxy I am using. I can now produce great looking ribs with no holes in the plywood, I don't have to waste and remove staples and my jig looks as nice as the day I built it.

Chris