Pivoting casters for stability and smooth travel
When designing a mobile base for my tablesaw and its extension table, I was concerned about how a four-wheeled base might twist and rack as the large, heavy saw moved across my uneven garage floor. Using the principle that any three points in space form a plane (like a tripod), I built a frame that includes both a triangular plane for stability and four casters for better weight distribution on the casters.
To create the tripod effect, I installed two fixed casters on the base at the heavy end of the saw to form the first two points of the triangle. For the third point, I built the pivot arm, shown in the drawing, and attached it to the base with a 1⁄2 x 5" bolt, washers, and nuts.
As the base rolls across the uneven floor, the two casters on the pivot arm are free to pivot up and down to conform to the floor, with the bolt acting as a pivot point. Yet, in use, the stand is as stable as any three-point wheelbase.
—Gordon Hofer, Santee, Calif