How do you fix table tops to the frame?

Paul tends to use turnbuttons, which are screwed to the underside of the table top and slot into stopped mortice holes in the aprons. You can get an idea as to what this looks like in the following blog:

We have made a video on making turnbuttons, which is available on our website if you sign up for a free membership (we also offer a paid membership which gives access to all of our projects including several tables which feature turnbuttons):