The first frame I fabricated I used HJ lugs as they were a real good fit to the tubes (Reynolds 531) I did it without help outside of the Paterek Manual and some basic knowledge from 30 years prior in a high school shop class. I kept in my mind the idea is to flow the filler (silver 54%) from one side of the lug to the other side where the flame was located. This is a simplified explanation, but it is the essence of what to do. On the first lug I saw how the silver flowed to the flame, and it made sense as to how to do it. The flame can also be used to "drag" the filler deeper into the lug, which I discovered on the first lug. Yes, a little bit of overheating occurred, but nothing detrimental to the durability of the frame.
Still riding that frame 20+ years and 20,000 + miles later. It is still a real pleasure to ride.