First we have to decide what size of coil we want to create. I’m going to be using enamelled copper wire 0.63mm in diameter, simply because it was easily available at the time.
0.63mm diameter wire is close to the American wire gauge size 22awg. A half kilogram spool of 22awg is about 280 metres.
I’ve made a coil former from a centre core of 60mm diameter, with side cheeks screwed on so that it can be dismantled after winding. In order to prevent the newly wound coil from simply springing apart when dismantling the coil former, I’ve taped string across the core in 4 locations around the former.
Once the coil is wound, this string will be tied to hold the coil together.