I use a small butane torch for everything. I'm an ac mech so i do lots of soldering. if you want to use silver solder and not melt anything get some cool gel.. takes the place of the wet rag and works fine and a peice of copper pipe.. flatten the end of the pipe and cut a notch in a big enough to just fit over the rod.. put it about an inch or two from the joint the copper will take the extra heat and when used with the gel or a wet rag should protect the nylon just fine.. this is how i solder. i flux up the piece, if i am doin say two rods. i do one empty rod first.. i coat the tip where i am making the connection first, reflux and solder it to the other rod. whick works good for wires to. hope this helps