Stumbled upon this whilst working on a project a few months ago. This guy’s method (I’d describe it as “shocking” the line) works surprisingly well.
How to Straighten Brake Line TUBING with (Common Hand Tools) I’d say it works very well with 3/16 brake line and plenty good enough when you get up to 5/16+. Have to kind of calibrate how hard you whack the vise grip depending on diameter of the tubing.
I still prefer to buy the straight sticks pre-flared when possible, but sometimes a run is long enough you can’t get those.
