A threaded rod securement comprising: a housing having a hole with a tapered inner surface, wherein the tapered inner surface has a wide end and a narrow end; and a threaded rod locking mechanism, wherein the threaded rod locking mechanism includes: plunger pieces (932, 934) movable within the tapered inner surface, wherein the plunger pieces have sloped outer surfaces that engage the tapered inner surface, and plunger piece inner surfaces (952, 954) for engaging threads of a threaded rod to be placed into the through hole; and a spring within the tapered inner surface providing a spring force biasing the plunger pieces (932, 934) toward the narrow end of the tapered inner surface; a back plate that blocks part of one end of the hole in the housing and includes an inner surface with threads that define a hole that is coaxial with the hole in the housing; and a set screw that can be selectively engaged to lock the plunger pieces (932, 934) to prevent uplift of the plunger pieces (932, 934) within the tapered inner surface, or to release to allow the plunger pieces (932, 934) to lift, the set screw engaging the threads along the inner surface of the back plate and including a through hole that is coaxial with the hole in the housing and the hole in the back plate, to allow passage of the threaded rod therethrough; wherein contact between the outer surfaces of the plunger pieces (932, 934) and the narrow end of the tapered inner surface drives the plunger pieces (932, 934) toward one another and toward a center of the tapered inner surface. a housing having a hole with a tapered inner surface, wherein the tapered inner surface has a wide end and a narrow end; and a threaded rod locking mechanism, wherein the threaded rod locking mechanism includes: plunger pieces (932, 934) movable within the tapered inner surface, wherein the plunger pieces have sloped outer surfaces that engage the tapered inner surface, and plunger piece inner surfaces (952, 954) for engaging threads of a threaded rod to be placed into the through hole; and a spring within the tapered inner surface providing a spring force biasing the plunger pieces (932, 934) toward the narrow end of the tapered inner surface; a back plate that blocks part of one end of the hole in the housing and includes an inner surface with threads that define a hole that is coaxial with the hole in the housing; and a set screw that can be selectively engaged to lock the plunger pieces (932, 934) to prevent uplift of the plunger pieces (932, 934) within the tapered inner surface, or to release to allow the plunger pieces (932, 934) to lift, the set screw engaging the threads along the inner surface of the back plate and including a through hole that is coaxial with the hole in the housing and the hole in the back plate, to allow passage of the threaded rod therethrough; plunger pieces (932, 934) movable within the tapered inner surface, wherein the plunger pieces have sloped outer surfaces that engage the tapered inner surface, and plunger piece inner surfaces (952, 954) for engaging threads of a threaded rod to be placed into the through hole; and a spring within the tapered inner surface providing a spring force biasing the plunger pieces (932, 934) toward the narrow end of the tapered inner surface; a back plate that blocks part of one end of the hole in the housing and includes an inner surface with threads that define a hole that is coaxial with the hole in the housing; and a set screw that can be selectively engaged to lock the plunger pieces (932, 934) to prevent uplift of the plunger pieces (932, 934) within the tapered inner surface, or to release to allow the plunger pieces (932, 934) to lift, the set screw engaging the threads along the inner surface of the back plate and including a through hole that is coaxial with the hole in the housing and the hole in the back plate, to allow passage of the threaded rod therethrough; wherein contact between the outer surfaces of the plunger pieces (932, 934) and the narrow end of the tapered inner surface drives the plunger pieces (932, 934) toward one another and toward a center of the tapered inner surface.