Design Help for A Table Base to Support Very Heavy Top

[Gene E Miller]

Greetings & Salutations,

I have been away for a long time but am happy to say I am about to dive into
a couple of new projects and I need some help with this one before I can
go to the next one.

I have a very nice polished Granite piece finished on all 4 edges that is
1 1/4" x 36" x 56" that we want to turn into a dining table.

Needless to say that thing weighs a bunch so I need to come up with
a table base that 1. Looks good and 2. can support the weight.

I have not built a dining table before so any suggestions or help with
this will be greatly appreciated.

I do not have at this moment in time any pre conceived ideas as to
style or design only that I have been told by a higher authority (LOL)
that the top needs to be that Granite slab.

Thanks in advance for all the good suggestions and advice that I know
I will receive here.

Gene

[Jamie Buxton]

A good start to dining table design is considering where the people are going to sit. My rule of thumb is that each person needs 24"x18" of table surface. With a 56x36 surface, you're going to have space for four people -- two on each long side, or one each of four sides. This means you could pretty readily put legs at the corners of the table. They wouldn't be in the way of any of the possible arrangements of four people, and there would be space for the chairs to be stowed under the table. (In contrast, if you try a pedestal base on a top that small, the chairs are going to run into the base when they're pushed in.)

So the basic design could be legs at the corners, aprons running from leg to leg, and mortise-and-tenon joints connecting the aprons to the legs. This is a nice straightforward construction job.

Aprons are usually 3/4" thick. However, considering the weight of the top, you might beef them up to 1 1/2".

[Gene E Miller]

Greetings & Salutations,

Thanks Jamie, in my mind I was thinking that a very basic design of legs on each corner would make
maximum use of the space on the table and if made beefy enough would support the weight.

Gene

[Jamie Buxton]

...in my mind I was thinking that a very basic design of legs on each corner would make
maximum use of the space on the table and if made beefy enough would support the weight. ..

The legs don't have to be particularly beefy. They're standing vertical, and the weight of the top is trying to compress them. They're very strong in that direction. You could make them 1 1/2" square cross section, and they'd handle the weight. I'd probably make them bigger than 1 1/2", but that's from visual consideration, not structural. In contrast, the aprons are running horizontal, and the weight of the top is trying to bend them.

[Gene E Miller]

Greetings & Salutations

I have been looking around for some designs that I think would do what I
want to do and also handle the weight of the granite top that I want to use.

I like the design of this table and with some dimension modifications would
work for what I want.

File.jpg

I just have one question.

If I were to eliminate the bottom end streachers and the the single center
streacher do you think this would still be a sturdy base to support the
table top. I like the drawers and I would modify the design to have smaller
drawers from each side so it would become a total of 6 drawers.

Please provide any opinions you might have.

Thank you.

[Kenneth Speed]

Hi Gene,

I think you should keep the stretchers to maintain strength and stability and make the base short enough to provide leg room at the ends of the table. I don't, however, know how much of an unsupported overhang granite 1 1/4" thick is able to handle safely.

Ken

[Don Kondra]

I just happen to be starting a similar commission.

The granite person suggested an unsupported overhang of 8" - 10" would be fine.

My design is in the preliminary stages but I am thinking A&C style gables with only top frames.

Legs are likely in the 3 1/2" square range with 4" wide rails x 1 1/4" thick, mortice and tenon backed up by an interior frame work.

BTW the top is 3' x 6' @ ~ 400 lbs.

Cheers, Don

[Carl Beckett]

I have had a couple different kitchen tables that have approx 3x3 legs and no stretchers. Its holding up fine. I think the key is to use solid joinery where it meets the aprons.

[Frank Drew]

I think the key is to use solid joinery where it meets the aprons.

I agree; Jamie's design suggestion along with sturdy construction (material plus joinery) will support this top just fine. With a table this small (relatively speaking), bottom stretchers would most likely interfere with diners' legs. This would be easy enough to check: make a mock-up table with stretchers clamped in place and sit at it as you would at the real table.