An electrically insulating formed channel member is made of a sheet of an electrically insulating material capable of being press formed that is cut to provide radially projecting portions. Thereafter, the sheet is press-formed to form a formed channel member including the channel portion and the projection portions and bent to extend along the inner corner of a rectangular pancake coil with the web located at the inner side of the corner curvature. The sheet material may preferably be a dray paper press board. Ripples may be provided in the sheet material prior to the step of press-forming. The moisture in the sheet material may also be adjusted prior to the step of press-forming.