Here is an idea that may improve yours, Ken: Take a piece of the 1/4 in brass tubing, slot it as you describe, and slide it over the ARC-5 spline.. Then take a short piece of the 9/16 tubing and slide it down over the 1/4 inch tubing to act as a locking collar as well as a reinforcement. Solder it in place on the 1/4 inch tubing if you wish. Wayne