A compound chop sawing machine comprising: - a base defining at least one work table for support of at least one workpiece; - at least one work head associated with said base, which is movable relative to said work table between at least one upper end-of-stroke configuration in which said work head is fully moved away from said work table and lower end-of-stroke configuration in which said head is fully moved close to said work table wherein the at least one work head is provided with a rotary circular blade at least partly emerging from said head and exposed for cutting of said piece, said work head comprising at least one auxiliary work table, for support of a further workpiece, associated on the upper part with said head and provided with at least one slot from which at least the upper portion of said blade emerges; - at least one guard device for at least one exposed portion of said blade, at the lower active portion thereof, which is alternately movable between a configuration at which it is retracted in said work head to release said active portion for engagement with said workpiece and an extended configuration at which it covers said at least one exposed portion; - wherein the machine further comprises a removable locking means of said guard device in at least one of said retracted and extended configurations, wherein said locking means is of automatic activation/deactivation type and wherein said locking means comprises removable interconnection means interposed between at least two of said work head, guard device and base, which means can be automatically activated upon positioning of said guard device to said retracted and/or extended configuration or upon positioning of said work head to the at least one upper and/or lower end-of-stroke configuration; - wherein said interconnection means comprises at least one catch for retention of said first plate associated therewith and adapted to be removably inserted in at least one housing seat associated with at least one of said base and work head for retaining said guard device in said retracted configuration; - characterized in that said interconnection means comprises at least one tailpiece associated in a rocking manner with said base, said housing seat being made at said tailpiece and said covering element being associated with said tailpiece; - wherein said work head is pivotally associated relative to said tailpiece, said tailpiece cooperating with said guard device for protection of at least one exposed portion of said blade when said guard device is in said extended configuration and/or said work head is in said upper end-of-stroke configuration. - a base defining at least one work table for support of at least one workpiece; - at least one work head associated with said base, which is movable relative to said work table between at least one upper end-of-stroke configuration in which said work head is fully moved away from said work table and lower end-of-stroke configuration in which said head is fully moved close to said work table wherein the at least one work head is provided with a rotary circular blade at least partly emerging from said head and exposed for cutting of said piece, said work head comprising at least one auxiliary work table, for support of a further workpiece, associated on the upper part with said head and provided with at least one slot from which at least the upper portion of said blade emerges; - at least one guard device for at least one exposed portion of said blade, at the lower active portion thereof, which is alternately movable between a configuration at which it is retracted in said work head to release said active portion for engagement with said workpiece and an extended configuration at which it covers said at least one exposed portion; - wherein the machine further comprises a removable locking means of said guard device in at least one of said retracted and extended configurations, wherein said locking means is of automatic activation/deactivation type and wherein said locking means comprises removable interconnection means interposed between at least two of said work head, guard device and base, which means can be automatically activated upon positioning of said guard device to said retracted and/or extended configuration or upon positioning of said work head to the at least one upper and/or lower end-of-stroke configuration; - wherein said interconnection means comprises at least one catch for retention of said first plate associated therewith and adapted to be removably inserted in at least one housing seat associated with at least one of said base and work head for retaining said guard device in said retracted configuration; - characterized in that said interconnection means comprises at least one tailpiece associated in a rocking manner with said base, said housing seat being made at said tailpiece and said covering element being associated with said tailpiece; - wherein said work head is pivotally associated relative to said tailpiece, said tailpiece cooperating with said guard device for protection of at least one exposed portion of said blade when said guard device is in said extended configuration and/or said work head is in said upper end-of-stroke configuration.