I have found that using a 2-1/2″ diameter hole that is 1/4″ deep is a good way to mount blanks for plates and shallow bowls on the lathe. It is easy and very secure.
It’s a lot better than using a chuck screw. Because chuck screws and shallow holes don’t mix well.
I drill a 2-1/2″ diameter hole that is 1/4″ deep with a Forstner bit. Then expand my 4 jaw chuck into the hole.
You also need to clamp the blank down to the drill press table. A big drill bit can easily catch and rip the blank out of and/or thru your hand. Any sharp edges or corners on the blank will shred your hand.
The cheap “Steelex” brand Forstner bits currently available on Amazon for $2x work ok. The Amazon reviews vary quite a bit. Getting a good one is a crap shoot. I have gotten 2 winners recently.
Note: Amazon dynamically prices everything. I purchased a new 2-1/2″ Forstner bit last week for $20. Today the lowest price it will show me is $28.91. If I wait a few more weeks then the price will probably go back down to $20.