Device and a method for moving a jet member

A device for moving a jet member (6) having a nozzle (14), said device comprising

• a carriage (4) movable in a first substantially rectilinear path along a guide member (3),
• first drive means (9) configured to move said carriage along said guide member for moving the nozzle of the jet member in said first path over a layer to be treated by the jet,
• second drive means (24, 25) configured to move the entire device and by that said guide member in a second substantially rectilinear path being substantially perpendicular to the extension of said guide member, and
• an arrangement (21) configured to control on one hand said first drive means for controlling the movement of the impact point of said jet on said layer and on the other hand said second drive means for moving the jet member to move said impact point on said layer an indexing step in said second path when moved at least once between end positions on said first path, wherein the device further comprises
• means (30) configured to enable input of data relating to a geometrical shape of a surface of said layer to be treated by the jet member, and
• means (33) configured to use said data for calculating end positions (S1, S2) of said impact point of the jet member for a plurality of consecutive stripes (S) extending substantially perpendicularly to said second path for indexing, each having a width substantially corresponding to said indexing step and together forming said geometrical shape, and
• said arrangement (21) is configured to control said first and second drive means (9;
• 24, 25) to coordinate movement of the impact point of said jet member between said end positions calculated of the respective of said stripes and said indexing of the jet member to treat a surface of said layer having said geometrical shape by said jet member.