Abstract: There is disclosed a doctoring apparatus for doctoring a cylindrical rotating surface of a machine. The doctoring apparatus includes a blade carrier assembly for holding a blade for doctoring a cylindrical surface. The blade carrier assembly further includes at least one movable tenon. The blade carrier assembly slides across a supporting surface of a doctor back. The doctor back includes a mortise which is sized to loosely receive the tenon to permit the tenon to slide within the mortise as the remainder of the blade carrier assembly slides over the supporting surface of the doctor back. Once the blade carrier assembly is located in a position relative to the doctor back, an adjustment mechanism carried by the blade carrier moves the tenon into locking engagement with the mortise. This adjustment mechanism is a releasable securing mechanism which allows the tenon to move in and out of locking engagement.