An evaporator for an ice making system comprising: a refrigerant conduit ; and front and rear plates sandwiching the refrigerant conduit , each of the front and rear plates having: inner flat portions , each inner flat portion of the front plate facing, but being spaced from, a respective inner flat portion of the rear plate to define a respective spaced portion ; a plurality of triangular fins dividing the respective plate into a plurality of ice forming columns ; a set of first protrusions defined in the respective ice forming columns , each first protrusion on the front plate facing a respective first protrusion on the rear plate to define a respective active cavity , the refrigerant conduit extending through each of the active cavities ; and a set of second protrusions defined in the respective ice forming columns , each second protrusion on the front plate facing a respective second protrusion on the rear plate to define a respective passive cavity , the refrigerant conduit not extending through any of the passive cavities ; wherein the active and passive cavities are interspersed and separated by respective inner flat portions so as to define a plurality of ice forming sites in the ice forming columns of the respective plate . a refrigerant conduit ; and front and rear plates sandwiching the refrigerant conduit , each of the front and rear plates having: inner flat portions , each inner flat portion of the front plate facing, but being spaced from, a respective inner flat portion of the rear plate to define a respective spaced portion ; a plurality of triangular fins dividing the respective plate into a plurality of ice forming columns ; a set of first protrusions defined in the respective ice forming columns , each first protrusion on the front plate facing a respective first protrusion on the rear plate to define a respective active cavity , the refrigerant conduit extending through each of the active cavities ; and a set of second protrusions defined in the respective ice forming columns , each second protrusion on the front plate facing a respective second protrusion on the rear plate to define a respective passive cavity , the refrigerant conduit not extending through any of the passive cavities ; wherein the active and passive cavities are interspersed and separated by respective inner flat portions so as to define a plurality of ice forming sites in the ice forming columns of the respective plate . inner flat portions , each inner flat portion of the front plate facing, but being spaced from, a respective inner flat portion of the rear plate to define a respective spaced portion ; a plurality of triangular fins dividing the respective plate into a plurality of ice forming columns ; a set of first protrusions defined in the respective ice forming columns , each first protrusion on the front plate facing a respective first protrusion on the rear plate to define a respective active cavity , the refrigerant conduit extending through each of the active cavities ; and a set of second protrusions defined in the respective ice forming columns , each second protrusion on the front plate facing a respective second protrusion on the rear plate to define a respective passive cavity , the refrigerant conduit not extending through any of the passive cavities ; wherein the active and passive cavities are interspersed and separated by respective inner flat portions so as to define a plurality of ice forming sites in the ice forming columns of the respective plate . <EOS>