Large Flat Dining Table - Design Ideas

[Bill Adamsen]

Im looking to build a single surface 5' by 8' dining table. The client is looking for a relatively massive appearance ... that is a side skirt of 4". The top is envisioned to be whitewashed rift sawn White oak or White ash (discussed in the finish forum).

Any thoughts on how to build this top in a way that keeps the weight manageable, and the surface flat? I was envisioning veneering an engineered structure (torsion box) of 1/4" material sandwiching an end-grain balsa or honeycomb (nomex) interior with a thick veneer surface. Would I be able to vacuum bag the structure without collapsing or distorting the core? Other ideas?

[Jamie Buxton]

I'd certainly consider making the top with just solid lumber. It will be heavy, but not outrageous. That is, the table would have those 4"-tall aprons running leg-to-leg, and a 1"-thick or maybe 3/4"-thick top resting on the base. There would also be a couple interior "aprons". The multiple aprons would keep the top flat. Use tabletop fasteners or buttons or the like.

[Wayne Lomman]

I agree with Jamie. He has the right idea.
Further, the weight saving ideas will sound hollow and cheap and the light weight will make it feel cheap. A big table needs some weight to give it credibility. Cheers

[Bill Adamsen]

Gents ... my apologies ... forgot to attach the rendering and "sample." It is evolving as a fairly modern design. Not that solid wood won't work. I'm leery of the stability and weight. Interesting that we consider weight
as part of the value proposition. I also question whether I can find solid wood with the rift sawn quality I think the client demands. They're expecting something that looks like a sheet of rift sawn WO plywood. Also, with a solid top I'd be potentially dealing with a cross-grain problem on the ends.

RiftSawnWhiteOak.jpgTable.jpg

[Steve Jenkins]

I think that I’d use solid stock 1” to 1-1/4 . Make it enough oversized to waterfall the ends and edges. I posted a couple pics of a rift sawn white oak table not too long ago.

[Bill Adamsen]

With air dried oak at about 45#/cubic foot ... an 1-1/4" table top (without waterfall) 8' x 5' would weigh in at 187 pounds according to my calculations. Likely 225 pounds or more with the frame components and edging (edging alone I calculate at about 30 pounds). And that is just the top. I just wrestled a slightly heavier oak built-in desk into place (built as a knock-down) and I just don't think solid wood is sustainable in these sizes and weights.

Has anyone done this sort of project with a torsion box, foam or honeycomb core where they could share best practices?

[Steve Jenkins]

The table I referred to was 42” x9’ x1-1/2” thick. About 180 lbs. you’re right it was heavy then add the base

[Jamie Buxton]

That drawing definitely suggests veneer. However, I would strongly suggest not using standard hardwood-veneer plywood, or the usual sliced veneer. That stuff is very thin -- less than the thickness of a credit card. Dining tables take hard knocks. They get dings and scratches, and 10 thousandths of an inch of veneer will not survive long. On top of that, using sliced veneer at the corners and edges is a fragile point. You also can't ease the corners for fear of going through the veneer. I use sawn veneer for jobs like this. I cut it at 1/8", and count on it being 3/32" or so on the furniture. That's thick enough to be sturdy, and thick enough that edges and corners can be done.

[Wayne Lomman]

The one I made in this style but a bit larger weighed about 330kg from memory. It was made out of sawn messmate veneer on a plywood core. Search out enough good quality timber to cut your own veneers as Jamie says.

A table like this is not generally considered to be portable. It needs weight for stability and the weight needs to be down low. You need to be able to sit securely on the end of the table with your feet off the ground. If you don't, someone will end up tipping the whole Christmas dinner in a pile on the floor one day.

Make the top and base so that they can be separated for getting in the door. By all means use a torsion box or whatever but you will be writing the book. Cheers

[Jamie Buxton]

You asked if you can vacuum bag a torsion box. Short answer: no. Here's the numbers... Atmospheric pressure is 14 pounds per square inch. You have a surface that is 60"x96". Multiply those together, and you're looking at 80 thousand pounds. You really have to veneer the surfaces first, and then assemble them into your torsion box.

[Tom Bender]

Vacuum Bag
You don't have to pull a full vacuum, just pull as much as needed. So that can work

Veneer
Agree with Wayne on making it thicker. Apply it to 3.4" ply. That will not sound hollow.

Stiffness
You could attach a 3" thick torsion box under the top incorporating longitudinal members to connect to the pedestal. Stiff styrofoam should work and be much cheaper than Balsa.