Help with large granite conference table
![](https://secure.gravatar.com/avatar/ceb1ee2fe8b7da407bab87e6deff6f6a?s=52&d=https%3A%2F%2Fimages.finewoodworking.com%2Fapp%2Favatars%2F200x200%2Fd.png&r=g)
I need to build a table leg frame to support a heavy 3?x8?x5/4? piece of granite for a conference table (~ 650#). Can anyone tell me how far I can safely cantilever the sides and ends of the granite over the frame? It’d be nice if the leg frame could be well out of the way of feet and knees, which is what requires the overhang. Any comments, suggestions, or info sources would be greatly appreciated.
Replies
Have you asked the vendor?
If you make the frame with 1" square steel tubing, you can bring it out to within a few inches of the table edge without it being visible or interfering with knees. You can build all the visible parts out of wood, screw the steel frame on top of that, and lay the granite on the steel.
Here's a thread with some discussion. If you search for "granite overhang" (without the quotes) at Breaktime, there are 34 messages with those two words. Or you can post your question at Breaktime.
http://forums.taunton.com/tp-breaktime/messages/?msg=46187.1
I'd certainly talk this design through with the granite supplier. I'd also remember that tables in business settings get abused in ways which wouldn't happen in residential settings. For instance, you might well get several people sitting on the edge of the table.
That said, you actually have quite a lot of height to make your cantilever very stiff. You can easily make the composite top (that is, granite plus wood) 3" thick without hitting anybody's knees. Your granite is probably 3/4" thick in the middle, built up thicker right near the edges. That leaves you over two inches for wood underneath the granite. You can make 2" of wood very very stiff, so a long overhang will not flex --- even with idiots sitting on the edge.
Jamie's got the right idea for a conference table. The edge can be much thicker than a cantilevered kitchen counter top.
What I did for my kitchen island, which has a 12 inch cantilever, was to do two things. I put 5/8" plywood on the top of the cabinets and had it cantilever exactly as far as the granite (minus the edge, which is double thickness). I then built some corbels which attach to the cabinets and come out about 10 inches. These corbels are about 24 inches on center. If the conference table top has an edge like a kitchen counter top, this support structure will work fine for you. If you place the corbels between the seats they don't interfere with seating. That's why I chose 24 inches on center. I have bar stools at the counter and everything works perfectly.
John
Thanks for all the suggestions everyone. I'll have my BIL check with the supplier too. Building the frame with some sort of corbels is one of the ideas we talked about early on, and exactly what I've started to design in some of the preview layouts.
Scotty --
The issue with corbels is that people may whack their knees on them. In a business conference room, folks are unlikely to pay enough attention to steer their chairs away from the corbels; they're focusing on business. In your place, I'd not use corbels, but instead make the cantelever itself very stiff.
Jamie
This forum post is now archived. Commenting has been disabled