Now that we're all caught up we can continue.
On Monday I laid out the template for the wingtip bows. This was made a little trickier because the dimensions are to the inside of the tubing, but the Zero position at each end is at the outside of the tubing. There are no dimensions for the endpoints of the inner curve, they just have to be extrapolated.
The dimensions are given from the tip rib at various stations, every 2 inches for the leading edge, and every 6 inches after that. I laid out on a piece of lauan. A nail was driven in at each point, and a thin strip of 1/16" plywood was sprung around the nails. You have to eyeball the curve to make sure it looks smooth, or "fair." This is the stage where you start extrapolating the end points; you make the line look right and make sure 3/4" tubing will fit the rib. In my case, one of the points was about 3/16" too far in to create a fair curve. This was shifted outboard and everything else worked out.
The next step is to bend the tubing, for which we'll need a bending jig. Many people have had good luck with an electrical-conduit bender. I have access to one, but for some reason I decided it would make sense to build my own bender. It's constructed based off a drawing from Tony Bingelis for bending 1/4" and 1/2" tubing. This was my first and only warning that I was heading down the wrong track.
Two pieces of 3/4" plywood were glued together and had a 3/4" wide round groove routed in the edge. Drywall screws reinforce this. A steel strap with a hole in each end was fabricated. This strap holds the tubing in place during bending via a bolt through the strap and plywood. All was looking good.
And then I tried to bend. The long, smooth bends came out great, but any of the sharper bends needed for the leading edge of the wingtip bow resulted in kinking. The plywood isn't strong enough to resist the outward forces of the tubing walls in tight bends and so the tube can kink, so that was about 4.5hours wasted. I think I will still use the bender for the gentle curves, but I need to get a conduit bender for the sharper curve in the wingtip bows.
The last project wasn't part of the airplane build, but I think it will make a significant difference in how I use the shop. I fabricated myself a little raked shelf to hold my laptop and charger. The shelf lets me see and reach the keyboard while keeping the screen at an easy viewing height. Now I can have my computer playing relevant/inspiring content while I work, and also puts reference material close to hand while keeping my bench clear. I am very pleased with this one.
On Monday I laid out the template for the wingtip bows. This was made a little trickier because the dimensions are to the inside of the tubing, but the Zero position at each end is at the outside of the tubing. There are no dimensions for the endpoints of the inner curve, they just have to be extrapolated.
The dimensions are given from the tip rib at various stations, every 2 inches for the leading edge, and every 6 inches after that. I laid out on a piece of lauan. A nail was driven in at each point, and a thin strip of 1/16" plywood was sprung around the nails. You have to eyeball the curve to make sure it looks smooth, or "fair." This is the stage where you start extrapolating the end points; you make the line look right and make sure 3/4" tubing will fit the rib. In my case, one of the points was about 3/16" too far in to create a fair curve. This was shifted outboard and everything else worked out.
The next step is to bend the tubing, for which we'll need a bending jig. Many people have had good luck with an electrical-conduit bender. I have access to one, but for some reason I decided it would make sense to build my own bender. It's constructed based off a drawing from Tony Bingelis for bending 1/4" and 1/2" tubing. This was my first and only warning that I was heading down the wrong track.
The last project wasn't part of the airplane build, but I think it will make a significant difference in how I use the shop. I fabricated myself a little raked shelf to hold my laptop and charger. The shelf lets me see and reach the keyboard while keeping the screen at an easy viewing height. Now I can have my computer playing relevant/inspiring content while I work, and also puts reference material close to hand while keeping my bench clear. I am very pleased with this one.
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