A machine tool comprising: a machine frame; a work carrying assembly for carrying a workpiece, carried by said machine frame for reciprocal movement along a work axis; and a cover assembly carried by said machine frame and including cover portions disposed to cover selected areas of said machine frame proximate said work axis. The cover assembly is not connected to the work carrying assembly but is operable to effect movement of said cover portions commensurate with movement of said work carrying assembly. The work carrying assembly includes a work carriage and said machine frame mounts a slideway proximate said axis and extending in the same direction as the work axis. The work carriage extends in the direction of said work axis but is of lesser extent than said slideway such that portions of said slideway to either one, the other or both extremities of said carriage assembly may be exposed upon said reciprocal movement of said work carrying assembly work carriage. The cover portions cover the slideways that may so be exposed. A first cover portion is disposed to cover the slideway to one side of the work carriage and a second cover portion is disposed to cover the slideway to the other side of the work carriage. Each cover portion includes a plurality of telescoping, slidably interrelated covers which are moved with respect to each other to cover more less of said slideways as such become exposed or become covered by the work carriage.