I'm surprised you were unsuccessful with heating. Not surprised it didn't work the first time, but after repeated attempts, because this sort of practice is exactly what is needed to help adjust the amount of heat needed.

There's a point, which we cannot describe in words, where the nylon stops being softened and begins actually melting. I think this is close to 200 degrees F, and the reason the book might suggest boiling water as a heat source.

Of course, once the nylon melts, it will not shrink back. My technique was also swaging, but the swaging force needed is tough to deliver to a somewhat flexible tubing; holding it is the problem you solved with the oak equivalent to the tubing clamp used in a flaring tool.

When I heated the tubing with the heat gun, I was applying that swaging force at the same time with the tubing clamped in my left hand, as much as I could, as the heat gun was manipulated in my right hand to GENTLY warm the very end of it. Being careful to confine the heat to the 3/4" at the end, so the swaging force would not distort the pipe further back was the tricky part.

But next time, I'm going to make a clamp like you did. My experience with those for flaring metal tube makes me ask: what length did you make your clamp? In other words, how much of the tube's length was in the clamping portion of the drilled hole? Have a photo? I love the vinyl tape fix, too.


--
Art Benstein near Baltimore

"I don't think you can get cold in Volvo 240 series. The AC can't do it and the heater won't let you." -darkdelta