Your 1" threaded rod has a yield strength in tension of approx. 35,000 lb. if you used mild steel.

The tensile load on the rod was probably on the order of 2,000 lb. or less.

The reason that you had to use 1" rod was to overcome the massive bending moment caused by the fact that the load was not aligned with the centerline of the rod.

On the Klann, or the clones, the load acts almost perfectly down the center of the actuation screw............thereby ensuring no bending moment on the screw............and allowing no risk in fully compressing the spring.

Any of the purchased side pull compressors with threaded rods of less than 1" are not satisfactory for the task.