Been catching up on chores and unplanned things, but hopfully once again this project can gain momentum.
With straight guage tubing once you determine how long you need the tube, you just cut and miter. With double butted tubing it's a little different. You are shipped a 680mm tube. I've determined it needs to be cut down to 632mm. If you look at the chart, they give you a 680 that has a thickness of .8mm for 102mm, then tapers 51mm to a thickness of .5mm, then maintains a thickness of .5mm for 324mm, then tapers for 51mm to a thickness of .8mm, then maintains a thickness of .8mm for 152mm (The Painted End). So if I cut it down to 632mm I have to cut off 48mm. If I cut it all off on the painted end. I end up with an almost balanced 102/51/324/51/104. But since the bottom bracket is where all the action is. It would make sense to make that butt a little longer. One the flip side, everytime I see a down tube fail, it's because it's buckled toward the head tube. Hmmmmm we will see tomorrow.