@Whippet, I suspect what you're attempting is a proper job rather than wood butchery.Hi.
Maybe I am old fashioned. My understanding is that the purpose of a screw is to clamp one piece to another piece. If you just drive a screw into two pieces of timber the screw will "cut a thread" into both pieces. So how does it clamp?
By having a clearance hole in the first piece under the screw head, the screw thread bites into the second piece and then actually clamps the first to the second piece. It can also be tightened at a later time if the timber shrinks etc.
Cheers.