My dad also made a tabletop for me years ago! Kudos to our creative fathers!
My goal was to be able to set up the new top by myself if necessary. If I remember correctly, Dad cut the plywood piece in half widthwise, thereby making the top in 2 pieces instead of just one. Underneath on each piece he attached a U-shaped frame made of wood pieces that measured to fit snugly over the blanket-covered real top. I could then sort of drop/slide each new end on. I seem to remember some kind of side bolting to secure them together (it was over 35 years ago).
I really like your dad’s addition of the half-round edges! Makes it safer to handle and prevents wear and tear on your tablecloths, I would think, besides more attractive once covered.

Hi Greg – I don’t know how to enlarge a round table except for making a new round top for an existing table using 2 x 4’s or 2 x 6″s. I am in the process of doing this right now to make my round dining table in my kitchen to be 60 in diameter. Right now it is 46″. Have you googled ” how to make a round table top out of wood. A bunch of YouTube videos will be listed.

Here is round table top extender that is pre-made: https://bit.ly/39s3lCJ

Hi James – Yes your idea would work on some tables depending how the underside it constructed. It would make it easier to just turn a baton to secure the top. Thanks for sharing your tip.

Hi Susan –

Around the edges of the table, it is not tape. There is half-round molding glued and nailed in with finishing screws. It is mitered at each corner. My dad added it to smooth the edges. Tape would work, though since the wood will be covered with a cloth. I would use a good quality of duct tape.