My bobbins are assembled by me in my shop. I use a precise measurement 3 part spacer system that allows the Alnico pole pieces to be firmly and accurately set into the forbon flatwork. The pole pieces are pressed into the flatwork with a 1 ton arbor press. The bobbin top is also pressed onto the pole pieces with a 1 ton arbor press. The fit is tight and precise and there is no need to glue the pole pieces in place as a result.
The pole pieces are either left flat or bevelled as required.
The assembled bobbins are lacquer dipped to minimize the potential of the coil shorting out due to usage over time. I built a fume hood for my shop for the sole purpose of venting the toxic lacquer fumes while the bobbins dry. The alnico magnets in the lacquered bobbins are wrapped prior to winding.
Bobbin Fabrication Equipment: