I'm building my first red oak board bow and have it bending nicely on the floor and want to put a string on it but haven't shaped the knocks I have left plenty of wood to shape them without overlays but wasn't sure if I HAD to put overlays on I would rather not and just have a nice clean horn shape out of the oak. Is this possible or problematic?

No you don't have to.

I almost never use them.

I never use them except to bolster a tip with a drying crack. Jawge

if ur  using a b 50 string forget the over lays  if ur  fixin to fool with fast flight then add the overlays  horn or hard wood  brock

awesome thanks alot guys I'll start shaping them tonight...man I love this site hahaha

Just don't cut into the back, just the sides.

I'm sure they aren't needed if you don't cut through the back but if you use the right wood,
wood combinations, or horn it can really set a bow off.  I like using a couple very thin layers of differing wood.  Use super glue and you can work the tips in less than an hour.

Aaron