More fitting and tack welding

more fitting and tack welding...

This is about as close as you have to fit the tubes. On the lower part of the joint I can just slip a 1/16th welding rod in at the widest gap. You can get by with a slightly larger gap occasionally but if your fit is a lot worse than this you probably need to take it out and redo it. Even if it is tack welded, it's very easy to grind off the tack weld and pull the tube out. You can almost always find a place where you need a slightly shorter tube and then use the removed tube after you cut off the end.

I placed all of the diagonal braces where I could...

Here I used a clamp to hold the tube in place while I tack the bottom. Then I can remove the clamp and tack the top of the tube.

Eventually, I had to remove the plywood jigs so I could place the remaining tubes. You can now see why I placed slots in the plywood... I only remove one station at a time and fit and tack the tubes at that station. That way, you can keep everything straight and true. Once we start welding, things will start to move around, sometimes quite dramatically. However, by staggering the joints when we weld (skipping around and not welding consecutive stations on the same side) we can mitigate this almost completely. Also, keep in mind that as long as the wing, tail and engine are in reasonable alignment with regards to each other, it doesn't really matter how the rest of the fuselage sits. You could be sitting in the seat listing thirty degrees to the port and the plane would fly just fine. But since aesthetics is important we will try to keep everything nice and straight!

My son is a sophomore at Vanderbilt and he always helps me out when he visits. He is actually building me a shelf/stand for the small refrigerator he got me for the shop for my birthday! He's got quite a bit of experience now building various things. He's done composite work on some aircraft parts, helped me build the shop, helped build a wood fired pizza oven, built a recumbent bike and helped me put a Chevy 350 engine in a Datsun 280z car amongst other smaller projects. He is a great help and I love working with him.

I constantly keep checking level at all stations. Now is the time to slightly tweak the frame while putting in the diagonals. All of these extra tubes are what locks in the shape of the frame.