Now that we have shown you several ways of making the mortises for floating tenons we should also tell you the best and easiest ways for making floating tenon stock. You should make some of this for each router bit size that you will be using for the mortises and just keep some on hand.
I use my surface planer to accurately make tenon stock in the router bit sizes that I commonly use. If rounded edges are desired to fit the router bit mortises I then cut them using a bull nose router bit of the appropriate size in my router table, but I don't usually bother with this since the strength of a tenon is mostly achieved by the sides of the tenon and glue bond to the sides of the mortise. I just make the tenon length fit the flat parts of the mortise. The 1/2 round hole at the end of the mortise that is left provides a good place for the excess glue to go. When I need floating tenons I just cut this previously prepared tenon stock into the lengths and widths that I need.
Charley