NOVELTY - The method involves providing an insert (102) with a side surface of approximately same shape as a connection face. The insert is positioned in an open mold (103). Layers of material (105) are placed in the mold to form a part (101) of a blade shell unit (100) in which the material layers are placed in abutment to a side surface (104) of the insert to form a side surface (108) of the shell part of approximately same shape as the connection face. Resin is provided to the layers and allowed to partly cure. The insert is removed. The insert is temporarily fixated to the mold.    USE - Method for manufacturing a part of a wind turbine blade shell unit of a wind turbine blade (claimed).    ADVANTAGE - The method enables manufacturing the wind turbine blade in an effective manner in sections or in parts yet assembled with sufficient joint stiffness. The method enables manufacturing the part of the wind turbine with improved control on geometry of bonding or joining surfaces, while reducing production time and cost on tooling and molds for the production of wind turbine blades. The method enables the shell part and add-on component to be connected closer to or at an erection site so as to greatly simplify transportation of the wind turbine blade. The method enables an angled surface portion to enable the shell part and add-on component to be connected in a scarf joint, thus yielding increased contact surface area between the connecting part and high joint strength. The method enables the insert to be held effectively in position by a simple unit so as to improve precision of the geometry and position of the side surface and the joint.    DETAILED DESCRIPTION - The material layers are fiber-reinforced sheet material layers e.g. glass fibers and carbon. The insert is made of plastic, wood and metal. INDEPENDENT CLAIMS are also included for the following:    (1) a wind turbine blade    (2) a method for manufacturing a wind turbine blade shell unit.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional perspective view of a mold for a wind turbine blade with a build-up of a shell part using an insert.    Blade shell unit (100)    Part of shell unit (101)    Insert (102)    Open mold (103)    Side surface of insert (104)    Material (105)    Side surface of shell unit (108)