Although the vast majority of 10-inch twin-tumbler examples are found with the bed supported on bolt-on, cast-iron box-type feet, early models (and a few of the later type)  had the tailstock end supported on a large plate formed with a large spring-load "ball" assembly. This arrangement, to allow some degree of self-alignment, or to prevent bed twist if bolted down to other than a flat surface, was also used in a simpler form by some other makers who employed a single bolt passing through a heavy dished washer sitting in a hemi-spherical housing machined in the underside of the foot..