Need advice in building this table

[TomFromStLouis]

Here is the underside of my factory built pedestal table. When the halves are pulled a support leg hinges down from each half. It is an adequate but not a robust bit of engineering.



As I mentioned above, my experience with this table has been that single pedestal design is best for round tables and if you want expansion leaves then simply choose a firmer base.

The OP's picture shows a table that is simply not meant to expand; the base cannot support a large cantilever.

[teetomterrific]

One more option... If you make the table where the central cylinder pulls apart and you insert and connect a stretcher between the two halves that would provide the stability and support you need. I wouldn't make the stretcher and leaf too big though. Maybe 24" or so. Possibly use alignment pins and secure the stretcher with clamp locks on the bottom. Secure one side, drop in the leaf, push it together and secure the other side. The stretcher would be the same width as the cylinder halves. at least on the ends.  You could make an inward curve along the length so it wouldn't feel so massive.

[ianab]

I'm going with "You can't always get what you wanted" 

 
The table in the picture looks nice, it's practical and relatively simple to build.

The curved legs like that mean you don't have the severe stress points that fail on most "single post" type tables.  I've to an old table in the shed they the MIL gave me because it had basically fallen apart. Big solid wood oval top of native Rimu that's like $8 a bf / ft to buy these days, so the top was worth saving. But if I rebuild it I will go with a solid trestle sort of design

Trying to make it extend is of course possible, but you end up with something mechanically very complicated like Tom posted (and not very stable). Or a bit "Mickey Mouse" with extra spare legs. 

Personally I'd go with the basic and elegant round OR something with a more stable base. Could be a round top on a more conventional base, that slid apart and converted into an oval. But having a more solid frame under it makes it a lot more practical.

[Mark A Smith]

Have the legs move with each side. You can buy hardware that is meant for an expanding table. However, the number and size of the leaves (24" each is about right) will depend on the expansion length of the hardware you can actually install with the fixed portions of the table.

Use dowels in the table and leaves and good leaf clamp hardware and you won't need extra legs.

[glzahn]

Thanks for all the great input.  Finally finished planting my garden and can now move onto other projects.  I'll re- read all the comments and take everything into consideration before I start the build.

Thanks again!!!