The ornamental design for a tablebase, as shown and described.
FIG. 1 is a first perspective view of a first embodiment of a table base;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a side view thereof, an opposing side, a front and a rear being identical;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a first perspective view of a second embodiment of a table base;
FIG. 7 is a second perspective view of FIG. 6;
FIG. 8 is a side view of FIG. 6, the opposing side, a front and a rear being identical;
FIG. 9 is a top view of FIG. 6; and,
FIG. 10 is a bottom view of FIG. 6.
The uniform broken lines shown in the drawings are included for purposes of illustrating portions of the table base that form no part of the claimed design; whereas, the non-uniform broken lines shown in the drawings are included for purposes of illustrating environment and form no part of the claimed design.