You made the decision you made based on what you knew at the moment, so in that context it was the right thing to do. Maybe you've recruited an appreciative colleague, or maybe not. That depends on his integrity, you've already demonstrated yours. Conversely, even though you attempted to help the guy out, did he get it? You can't control that, so it's not on you. But as you've probably learned in life, some folks you can communicate with some you can't, no matter how skilled you are, and how much you've tried. Hopefully he has the welding skills to finish the job properly.