To create perfectly expanded tubing for soldering or brazing,you must use soft copper or fully anneal end of tube to be expanded

Six Easy steps:
1. deburr inside of tube.
2. anneal the tube if necessary(for hard or thickwall tube).
3. screw the expander head on expander.
4. put the end of tube on expander head.
5. tighten the relief valve knob to n position then pump handle until tube is expanded to the end.
6. Return the relief valve knob to FF position to loosen expander head. remove expanded tube.