A wire saw with an endless diamond wire (w) - wherein said diamond wire (w) is arranged to run between two generally parallel guide liner pipes (1a, 1b) - wherein said guide liner pipes (1a, 1b) are arranged to be inserted into each one of generally parallel boreholes in rock, for a section between said guide liner pipes to be sawed out, - wherein said guide liner pipes can be arranged in pairs of parallel drilled holes to form a cut out hole with polygonal cross-section such as rectangular, - said guide liner pipes can be (1a, 1b) arranged in generally horizontally drilled holes, - wherein each guide liner pipe (1a, 1b) comprises oppositely facing slits (5a, 5b) to allow said diamond wire (w) to run to an opposite of said guide liner pipes (1b, 1a); characterized in that - each said guide liner pipe (1a, 1b) is provided with a longitudinally extending wagon with a motorized tractor arranged to pull said wagon along a guide rail within said guide liner pipe (2a, 2b); - in that each said wagon with said tractor is arranged as leading in the worming direction of said wire saw in said guide liner pipes (1a, 1b); - in that each wagon is provided with a front wire wheel (6a, 6b) and a rear wire wheel (7a, 7b) arranged to guide the diamond wire (w) internally between themselves in each guide liner pipe (1a, 1b), and wherein said diamond wire (w) runs in its cutting direction across between said guide liner pipes (1a, 1b) from one of said front wire wheels (6a, 6b) to an opposite of said front wire wheels (6b, 6a); - in that at least said two front wire wheels (6a, 6b) are driven each by its separate motor (8a, 8b) and arranged to drive the diamond wire (w); - in that said guide rail is a pitch rack rail and wherein said tractor is provided with a motorized driving gear wheel towards said guide rail and with one or more back supporting wheels to keep said gear wheel steadily towards said guide rail; - in that said diamond wire (w) runs in its return direction across between said guide liner pipes (1b, 1a) between the opposite rear wire wheel back to said rear wire whee; - and in that each wagon comprises a telescopingly extendable stem, each with a linear actuator arranged to tighten said rear wire wheel (7a, 7b) in a backward direction relative to said front wire wheel (6a, 6b) in order to put said diamond wire (w) under tension. - wherein said diamond wire (w) is arranged to run between two generally parallel guide liner pipes (1a, 1b) - wherein said guide liner pipes (1a, 1b) are arranged to be inserted into each one of generally parallel boreholes in rock, for a section between said guide liner pipes to be sawed out, - wherein said guide liner pipes can be arranged in pairs of parallel drilled holes to form a cut out hole with polygonal cross-section such as rectangular, - said guide liner pipes can be (1a, 1b) arranged in generally horizontally drilled holes, - wherein each guide liner pipe (1a, 1b) comprises oppositely facing slits (5a, 5b) to allow said diamond wire (w) to run to an opposite of said guide liner pipes (1b, 1a); - each said guide liner pipe (1a, 1b) is provided with a longitudinally extending wagon with a motorized tractor arranged to pull said wagon along a guide rail within said guide liner pipe (2a, 2b); - in that each said wagon with said tractor is arranged as leading in the worming direction of said wire saw in said guide liner pipes (1a, 1b); - in that each wagon is provided with a front wire wheel (6a, 6b) and a rear wire wheel (7a, 7b) arranged to guide the diamond wire (w) internally between themselves in each guide liner pipe (1a, 1b), and wherein said diamond wire (w) runs in its cutting direction across between said guide liner pipes (1a, 1b) from one of said front wire wheels (6a, 6b) to an opposite of said front wire wheels (6b, 6a); - in that at least said two front wire wheels (6a, 6b) are driven each by its separate motor (8a, 8b) and arranged to drive the diamond wire (w); - in that said guide rail is a pitch rack rail and wherein said tractor is provided with a motorized driving gear wheel towards said guide rail and with one or more back supporting wheels to keep said gear wheel steadily towards said guide rail; - in that said diamond wire (w) runs in its return direction across between said guide liner pipes (1b, 1a) between the opposite rear wire wheel back to said rear wire whee; - and in that each wagon comprises a telescopingly extendable stem, each with a linear actuator arranged to tighten said rear wire wheel (7a, 7b) in a backward direction relative to said front wire wheel (6a, 6b) in order to put said diamond wire (w) under tension.