Fin Brace Tubes
08/20/12 13:37 Filed in: All
I got out my torch and bent the tubes that are to support and align the tailfeathers. As with most operations that are new to me, the first one came out great, then the second two were sloppy I need a better device for squeezing and bending the heated tube that is a little more precise. I am going to do some experiments to see how strong the heated and bent tubes are as that is a questionable procedure in my mind. I am heating the tube with a pair of MAP gas torches which gets the tubes bright orange, but not cherry red. Good thing I bought an extra 3 feet of tubing from A.S.
I ended up grinding some generous curves on the outside of a couple of chunks of aluminum angle to cover the vice jaws, so that when I squeezed, the hot tubing it would have a gentle bend instead of a sharp break at the end of the angle.
Every time the tube is heated and squeezed the aluminum picks up some scale from the steel that has to be scraped off since it’s hot enough to braze the scale to the aluminum surface and stick.
Once the hot tube touches the jaws you have about 2 seconds to complete the bend before the heat is wicked away and the tube re-hardens.
Once the squeeze and the angle look good, reheat and get the whole bend bright orange to re-anneal and let it cool very slowly. I played around with more rapid cooling on test pieces and it makes a huge difference. I had one piece so hard that drill bits could not get any bite at all and just burned.