This is one of the more frustrating problems I haven't been able to shake. I keep getting a bend between sections after ferrules have been set. I can't diagnose where exactly the problem is coming from but it's pretty consistent from one build to another.
I use a wood lathe to prep both sections of a rod doing my best to center the section as much as I can. I use a file initially then sandpaper until the ferrule fits. I use top quality CSE ferrules. The final lapping of the male ferrule is done with steel wool so it fits the female end and typically only bare minimum amount of work is needed here.
Nevertheless, when the glue dries and I put the rod together the tip will sit at an angle. I work around this by trying different positions until the bend is downward facing so at lest the rod looks straight when you look top down its length and after adding guides and everything it's less obvious, but this is far from ideal and extremely frustrating.
Any ideas or suggestions?