Drip edge on bottom side of window sill...

Windows

I am going through my house window by window restoring them. THey are double hung with big sills. I just noticed that the underside of the sills don't have that little groove that modern windows have, which i presume to be a drip edge. Questions are -- is it worthwhile to cut one in while I am already working on the windows, and how would I go about doing so with the sill in place? Thanks for any insights.

jlhaslip

is the bottom of the sill horizontal or tipped down?
If there is a tip to the sill or apron, you won't (shouldn't) need the kerf cut.

consider using a palm router with a spline bit.

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Windows

Thanks for the advice. They are horizontal and from the way the paint has peeled under the sills, I should have guessed a kerf cut would be necessary. Thanks again.