We claim the ornamental design for a portion of a saw blade, as shown and described.
FIG. 1 is a top perspective view of a portion of a saw blade embodying the invention;
FIG. 2 is a right side elevation view thereof, the left side elevation view being a mirror image thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof; and,
FIG. 5 is a back elevation view thereof.
The structure depicted by means of broken lines in the figures has been shown for illustrative purposes only and forms no part of the claimed invention. The portions of the saw blade shown in broken lines having unequal length segments illustrate the boundary of the claimed design and form no part of the claimed design.