Since you have a 20" dia plate I'd be tempted to put a "real" load
bearing surface in the center of the plate (assuming that it won't be
visible) and regard the scroll feet as only semi functional feet. In
this case they could be fastened to blind nuts, perhaps hanger bolts in
the feet connecting to threaded inserts in the bottom of the 20" dia plate.

RB

GonnyGump wrote:
Bottom line: Which is stronger, lag bolts or carriage bolts?

Context and details:
I am building a large (12' long) oak dining room table, the base for
which will be two 18" diameter circular columns. Each of the columns
will sit on a 20" circular "plate" (about 4" thick) that, in turn,
will be supported by four scroll feet. The scroll feet will be
cantilevered out from the plate by about 6". My question is how best
to secure feet to the plate. The two options a a) 4-1/2" lag
bolts up through the heels of the feet and into the plate; or b)
carriage bolts following the same path through the feet and plate and
secured with a nut countersunk into the top of the plate. Can anyone
advise me which will be more secure, both structurally and against any
potential wood movement?

Thanks in advance for useful insights and comments.

jdc