Plastic mold fixing structure for chassis

A molded plastic fixing structure for a chassis, comprising:

• a chassis having upper and lower surfaces and a substantially circular central opening therethrough;
• a substantially cylindrical boss disposed in the opening in the chassis, and extending above the upper surface of the chassis, said boss penetrates through said opening and substantially contacts the chassis within said opening;
• at least one of upper and lower substantially rectangular boss supporting sections integrally formed with the boss, said boss supporting sections being flush with the corresponding chassis surface, each supporting section including a width dimension which is substantially greater than a diameter of said boss;
• a substantially rectangular fixing support groove recessed around the opening and disposed in at least one of the upper and lower surfaces of the chassis and having a predetermined depth and a predetermined size from both the upper and lower surfaces of the chassis, said support groove having a width dimension which is substantially greater than a diameter of said opening, said fixing support groove preventing said boss from dislodging from said chassis during rotation of said boss, said opening and said support groove are aligned along one central axis, said opening intersects said support groove, and at least one of said upper and lower boss supporting sections being molded and disposed in and contacting the corresponding fixing support groove;
• and
• a movable member mounted on the chassis at the boss so as to move in contact with said lower surface of said chassis and said boss supporting section.