Well this is some of the finer welding I've done! And by that I don't mean best, I mean I had 2.5x cheaters in my helmet and wore 3x reading glasses. I did have the seat post in just past the weld area, and after every 3/8" of weld I would spin the seat post to cool the weld and make sure it wasn't seized in place. I did only drill a 3/8" hole in the seat tube before the welding. After the weld, I opened up the lock tube with a die grinder and smoothed the inside of the seat tube with a tiny drum sander on a die grinder. A little de-burring with a chainsaw file and that's as good as it gets.