Hi Brian,
Yes that’s also an option depends on what goes on the 13mm diameters in the finished article.
It’s also possible to start with the 13mm diameter pieces produced with the cutters sweep a given
Slope and length around the ends then use the new edges to sweep the main circle thus creating the larger diameter.
I did an experiment this way but the larger circle is not concentric to the 13mm and not necessarily a perfect circle.
Cheers
Barry