The parting bead that separates the 2 sashes in an old window needs to be
replaced. The wood itself is a stock item, but it needs to be grooved to
accept the zink knife edge flashing. The upper half would be grooved on the
outside, the lower half on the inside. These grooves are considerably
narrower than the kerf on my table saw blade. What is the best way to make
them?

Thanks,

Henry