I decided to weld in the bottle bosses on this frame and that turned out to be a bad decision. I did a test in a scrap piece of tubing and ended up completely melting the boss, because the arc tends to jump to the sharp edge of the boss and there isn't much mass, so it just melts. I did get the two bosses welded in to the seat tube, but it wasn't pretty and I ended up going to the mill to mill the faces flat. The bosses on the down tube went a bit better. I tried putting a stainless bolt and washer in the boss, while welding, to act as a heat sink and the washer helped with protecting the edge of the boss. I also raised the AC frequency, on the advice of someone who had experienced the same issues, and that also helped. I can say with some degree of certainty that any future frame will have Rivnuts installed for bottle bosses.
