There's the old-fashioned drop leaf and gate leg tables which I suppose technically do that, but I suspect you're looking for something larger. I'm curious and will be following this search! :)

We talked about drop leaf but he wants a table that can be sat at comfortably most of the time but expanded outward for company.

Some drop leaf tables can be comfortable for two, but mostly older ones. My mom's old MCM cherry drop leaf dining table was quite comfortable for sitting at the ends. I would look around in thrifts and consignment shops. Most of the newer tables use heavier bracing on the ends to compensate for shoddier construction.

ETA The reason I suggest looking for an old table is that they sometimes have a complex but shallow system of metal braces hidden under the table, as opposed to the large wooden sliders so common nowadays.

There are some really cool round tables that expand.
expanding round table

That is really cool, graywings, but if the sections drop down when it's open, doesn't that mean it would be too high when closed or too low when open? That's about a 4" difference as far as I can tell from the video.

What is the desired length and width (closed and open)?

Not really sure, Oaktown. I guess I'm looking to see if such a thing even exists.

Wow, graywings. That is really cool and impressive.

My parents have a square pedestal table in their family room that is based on a drop-leaf. But, they drop down from UNDER that table. When not in use, they fold back up under the table and latch, and the table seats 4. When they flip the curved leaves up and latch them, the now-round table seats 6 comfortably, and up to 8 if we use slightly narrower chairs. Sometimes they just have two or three leaves up. The chairs that go with the set are kind of game chairs, wide with arms. They got this table in 1971, so I have no idea if they are still made. But, check out game tables as opposed to dining tables, and you might find something like it.

I have a table that does this; it's a vintage enamel top table and the two wings are tucked under the center portion when not in use. There are springs and braces and such. It's not huge- four person when closed up all the way, a comfortable six or tight eight when open all the way.

This isn't my table although it's very similar, I see them at my local antique shops fairly often in several colors with varying levels of decoration.

open:

How it closes up, the leaves do go all the way flush:

Our prior breakfast room table was a 36x54 rectangle that had a butterfly leaf and opened up to a 54" square.

A table can be made to open in either direction, but opening on the length may present greater support challenges.

Of course, you can always turn the table. Most tables move easily enough to do that for occasional use.

Search for flip top table....rectangular dining will narrow it down....

these are vintage but showed the mechanism best. I think there are new ones available. Some nice ones on firstdibs, too, but $$$.

Such a cool idea

I am a long time lurker here but I have jut what you asked about. I bought it from a furniture store in Manhasset N Y , believe it began with a D but they closed.

My table is oblong and hinged on one long side, the hinges are a little decorative and not at all intrusive . You swivel the table top (it has like a large peg in a hole underneath) so that the table top which is two thickness's lays across the base exposing half of the base. Then open on unhinged side and lower, it will lay across the exposed base.

I end up with a large square table, seats very easily 8 persons and can be 12 .

This sounds cumbersome but is not at all. I can do it on my own and am "getting on in years" The table top when open, is an inch thick.

I know the table was made in Italy , mine is dark Jacobean oak colour and a hard wood but do not know what type it just might be European oak as looks a lot like my family furniture from UK.

If he is planning to use a tablecloth, another expansion option might be to make (or have made) a wooden table topper.

Example:
http://inmyownstyle.com/2011/11/how-to-enlarge-a-dining-table-for-extra-seating.html

I forget about it at times, but we have a console table that opens up like that. We use it in fron of the FR sectional at the holidays so we have have another table for dining -- and game playing. Ours has pull out arms for support on the ends of each side. We bought it new about 12-14 years ago and they called it a butterfly table at the time. Our outdoor table is a circle that opens to an oval. You might be able to tell that I like versatile furniture.

If you aren't finding something new or resale through the usual channels, tables aren't that bad to have made custom (well, most of them). Custommmade is a website that connects artisans with folks looking for something unique. I looked there before we found someoen local who made our new table. No, it doesn't change size, but he did make it so we can use it as a counter height now and have the option of reducing it to a regular dining height. ;)

I think you're complicating this. Just get a table that is the width you want and make sure it has multiple leaves. Do be aware that finding cloths for wide tables is VERY difficult! How do I know this? Because both my daughter and I have them and it's the devil to find a cloth that fits.

Rough Linen makes bedding to 120 inches wide. In fact, she's sjown bedding used over tables. I thnk they can make a tablecloth for any table ikely to be used in a home setting. And probably then some.

I'm showing my bias here. When I think of a cloth for a DR table, I automatically think of linen damask and they're no longer made by Ferguson in truly wide widths. Ferguson makes virtually all the Irish linen damask in the world.

Fabrics Store sells linen yardarge. The white rose jacquard is 75 inches wide -- which is probably why you see tablecloths up 70-72 inches wide. I thought I saw something wider, but it either wasn't there or they don't carry it now.

Would this table from Crate and Barrel work for you? It comes in 2 sizes:
http://www.crateandbarrel.com/flip-small-bruno-dining-table/s570092

Check out SKOVBY round expanding table. It is way cool. We saw it in Arizona. Or check out Wayfair using 'extension".

The Crate and barrel table is the same design as mine . Mine is solid wood and curved legs. I see that one is made in Italy too, maybe it is a common design there.

http://www.magisdesign.com/elenco_prodotti/piggyback/

Wow, oaktown. That is an awesome design! The guy said he wants a rustic table, but I'm going to show him this one! Thank you!

So we just saw a tj max commercial and they have the coolest table. It expands length wise and the extension sits under the table and pops up when you pull out the outer edges. This is a great expandable table. So I’m on the hunt for this one. I recorded the show so I’ll take some screen shots and post.

Did you find out about the table? Loved the design and want to make .I have two great walnut planks and would add a center tiled section that would drop down

Any updates for this?

I have an ornately carved RJ Horner that looks like a partners or trestle desk - with a mechanism wherein if you grab it on one of the long slides and pull outward, two leafs on hidden tracks go outwards and then upwards to join the height of the middle .

It goes from the size of a desk to a dining table.

it's quite nice.

I don't know if anyone is following this thread but shoot me an email at airixair@gmail.com if you're interested in seeing more.

I am following and interested to see any pics or links if anyone has...

Sarah Richardson did a home using a dining table that expanded width-wise rather than the customary lengthwise. See https://www.youtube.com/watch?v=xTuqej2o364 where the table is featured at 18min, 45 seconds into the you-tube presentation.

sjb3ip - please see https://www.youtube.com/watch?v=xTuqej2o364 where the table is featured at 18min, 45 seconds into the you-tube presentation.

That looks like what I’m looking for (in Sarah Richardson video) now where to find??