The ornamental design for a steamgeneratingbase for irons, as shown and described.
FIG. 1 is a left side view of a steam generating base for irons;
FIG. 2 is a right side view of the steam generating base for irons;
FIG. 3 is a front view of the steam generating base for irons;
FIG. 4 is a rear view of the steam generating base for irons;
FIG. 5 is a top view of the steam generating base for irons;
FIG. 6 is a bottom view of the steam generating base for irons; and,
FIG. 7 is a top perspective view of the steam generating base for irons.
The broken lines shown in the drawings of the steam generating base for irons are for illustrative purposes only and form no part of the claimed design.