[My job got in the way of progress on this project for a couple of weeks, but I am back to it, at least this week.]
Having started the extension table, I thought this was a good time to consider how I was going to mount it to the Incra fence. The Incra TS-LS Owner's Manual, on page 11, tells you exactly how to do this – for a 3/4” table:
The strip should be 1-3/4” high to support a 3/4” table. If you use these dimensions, the extension table top will align with the saw top. They suggest drilling a 3/8” hole for a 1/4” bolt to give some play for adjusting it.
But my extension table is two slabs of 3/4” MDF with Formica on top and bottom, for a total thickness of 1-5/8”. By subtraction, I determined that I needed strips 7/8” high, and made prototypes that were not long enough, using scrap plywood. Because 1/8” protruded from the bottom, I decided to cut the final strips, of oak, as 3/4” square. I recalculated the position of the holes accordingly, drilled them, and mounted one:
Cutting a strip to the thickness of the table, I tested the mounting and thought I would be able to get the extension table aligned properly.
-- Mark, hack amateur woodworker, Medford (greater Boston) MA