It starts out with loud, jarring vibrations and large flying chips of wood, as I rough out a cylinder from crude cuts of maple. It then becomes a more delicate process, carefully removing mass to the approximate dimensions of the final mandrel. Then, with about 1/8″ to go, it becomes a labor of immense patience, removing wood by dust, film, and wafer. There’s no way to add back material once it’s gone.
When I am done, I have the three mandrels I use to make the boilers. Including drying time for the glue used to laminate them together, the whole process takes about two days. After all that time making them, I take extreme care protecting the mandrels, practically taking them to bed with me. Since they’re made of wood, they’re very sensitive to humidity, and I’m almost superstitious about what environmental change could leave them warped and unusable.