An arrangement of a motor saw and an adapted guide bar arrangement for a motor saw arrangement ("A"), wherein said drive motor unit with its chassis comprises a drive motor unit, the rotatable shaft of which is adapted to carry a drive disc, such as a toothwheel shaped around the periphery (4"), around which toothwheel a portion of an endless saw chain is adapted to run and which saw chain also is adapted with its remaining portions to run along said guide bar arrangement and its guide bar and along side edges directed away from each other and its allotted tracks (2a', 2b') and to the outer end area of the 20 guide bar allotted, by the translation motion of the saw chain, a driven relinking disc, such as a toothwheel or similar, and wherein the motor saw arrangement ("A") with its drive motor unit is adapted to support said guide bar arrangement over an arrangement adapted for clamping an inner end area facing the chassis of the guide bar, such as a clamping arrangement, said arrangement being adapted to be able to take an activable position wherein the chassis included in the drive motor unit becomes solely and is fixedly anchored related to the guide bar arrangement and its guide bar or an inactivable position in which the chassis of the drive motor unit is loose and freely related to the guide bar arrangement and its guide bar and in this inactivated position, by a relative motion or displacement in a direction from the drive motor unit and its chassis, releases from the drive motor unit and its chassis (1 a) said guide bar and during the mentioned inactivating position indicates a pattern of action i.a. for removing the guide bar from the chassis, wherein said arrangement can be brought to said inactivable position by loosening a clamping means and during this inactivated position of the arrangement loosening said saw chain from the guide bar and its relinking disc and displacing the end portion of the guide bar and its drive motor facing end portion along the guide bar allotted, through away-directed side edges of the guide bar oriented plane ("P") and out of the inactivated position of the arrangement, wherein from a clamping position for said guide bar arrangement and to a free position thereof said clamping arrangement is formed as an interrelated arrangement, wherein said interrelated arrangement is allotted a fixed support plate and a displaceable clamping plate coordinated with the support plate for clamping with said clamping means the inner end portion of an intermediately positioned guide bar, wherein the interrelated arrangement is adapted to be brought to an inactivable position for letting the clamping plate be released by loosening the clamping means and the clamping plate and/or the end area for in a first mode of motion being displaceable at right angles a distance ("e"), which distance "e" is exceeding a thickness of the guide bar in a direction from said support plate,but still remaining interrelated or linked together with each other and within a second mode of motion immediately following the first mode of motion letting said end area and guide bar be brought or displaced along said plane ("P") allotted to the guide bar and out of an inactivated interrelated arrangement, and wherein the support plate tightly anchored to the drive motor unit or the movable clamping plate relative to the arrangement is provided with two short projections (7a1, 7a2), each one being adapted for cooperation with recesses (21a1, 21a2) allotted to the guide bar and with between the projections shaped clamping means, such as one with an associated threading, which in its activated position is adapted to hold and clamp the inner end area of the guide bar against the support plate, characterized in that the short outwardly directed projections (7a1, 7a2) of the support plate are each one provided with a circular cross section.