Large Double Pedastal Extension Dining Table

[simeond]

Okay - so I'm seeking out as much help as I can get with this one. I'm relatively new to professional furniture (I've been a hobbiest for years). Its my most ambitious project and I'm overthinking everything! Here's a sketchup model of the table:

The table is 48"x84" closed and 48"x120" fully open.

The top is a veneer of quarter sawn figured ribbon mahogany (african) with a border of 1/4" Peruvian Walnut, 1.5" Crotch Mahogany, and then 1/4" Peruvian walnut again. It will be on a 1" MDF substrate (with the border 2" solid Peruvian Walnut with the Crotch mahog inlayed into it). Here's the border:

The Pedastals are solid Peruvian Walnut. The pedastals:

Sooooo, here's my questions:

1) The curved legs. I am planning on laminating 1/8" strips of the walnut around a form for the legs. I thought this would be superior in strength to jointing up enough boards of the walnut to just cut the curved legs out (leaving vertical seams in the curved leg). Any other thoughts?

2) The pedastals are connected at the top by stretchers, but there is no lower trestle. Should there be? The pedastals are stationary, just the top expands.

Suggestions on these questions or any other issues that are apparent from the model would be helpful!

Thanks!

[Mike M]

It's hard to tell dimensions from your sketch, but the pedastals look a little small for the top. I have a double pedastal DR table (factory made) that is 46x72 when closed. The legs at the bottoms of the pedastals form a 27 inch square. If the base is too small, the table could tip if someone leans on it too hard. This could occur if someone uses the edge to help himself in standing up.

The pedastals on my table are connected to the halves of the top and move when the table expands. There are a pair of slides in the middle to support the leaves. There is no problem with the lack of stretchers since each pedastal is self supporting. Stretchers are only necessary when the pedastals are 'T' shaped.

[Darnell Hagen]

1) The lamination is a good idea.

2) The stretcher would strengthen the assembly, but ruin the design.

Are you sure about your top dimensions? It's gonna be BIG, especially when opened. Heavy, too, with the MDF core. I'm assuming you're using extension rails, if so it will either sag between the pedestals or droop at the ends. I agree with Mike that it looks tippy.

I've blogged about making several different kinds of tables, perhaps there's something there to help you out-

[simeond]

Thank you for the suggestions.

I agree with both of you about the "tippiness" of the table. I have expanded each pedastal and moved them apart slightly, but still only have a 21" square at the base (30" at the top). The pedastals are 18" apart at the base (12" at the top), giving a final length of 60" at the base and 72" at the top. I will be using 2 3/8" equalizer glides which go from 50" to 109". In fully open position, again there will only be 12" gap unsupported by the pedastals in the middle and a 2' overhang on either end. Do you think the slides will "droop" with that overhang? The table will only rarely be extended this far.

Here's the pedastal construction without the top/apron:

Here's the table in fully open position:

And here it is in closed position:

Let me know what you think regarding these changes (particularly if you think it still looks tippy).

Thanks again.

P.S. Darnell, great blog. I'll be spending the evening on it...

[bois]

For a project like this, I would highly recommend building a prototype before the finished product. There are some potential concerns about the stability of the table and proportions here that you really can't go back and fix once you start building the final piece. This is exactly the type of thing that's gotten me burned by Sketchup in the past. Even something just made out of mdf at half scale will tell you a lot (obviously this is a huge piece and doing a full-size model might be asking a bit much). I'd do a model in the fully open configuration.

Definitely laminate the legs too. Once you build the form, you should be able to batch them out pretty easily. Hopefully you have a drum sander to speed the process of cutting the laminates.

Definitely looking forward to seeing the progress and final product on this one. This looks like the kind of design I might end up with if I were tasked with the same job (I'm not sure if that's a complement or a curse though).

[JMadson Custom Wood]

Please build a prototype. That design just does not look safe to me. If I'm reading this right, you want a 21"x60" base for a 48"x120" table. That seems very small in both length and width.

[Mike M]

First of all, why are you keeping the pedastals fixed? The normal approach for this type of table is to fasten the pedastals to the two main sections of the top and have them pull apart so you can add the leaf (leaves) in the center. This solves the long overhang (30") at the ends when the top is opened. You could then use normal glides (not equalizers) to connect the top halves and support the leaves.

Next issue is the tops of the pedastals. I'm guessing that you are making the tops wide enough to support the slides. Again, if you used the conventional approach, the pedastals are fastened to the centers of the tops and the glides are fastened to the tops about 8-12 inches from the edges. The size of the pedastal tops adds little in stability as long as they are a reasonable size. In the classic tables, the pedastal tops are only about a foot square.

As far as the tippiness of the table, I would expand the bottoms and shrink the tops of the pedastals to give it a more grounded appearance. As far as safety is concerned, if you know the weight of the table you can calculate the force in each direction that it would take to tip the table. Think back to the levers you learned about in your high school physics class.

Mike

[simeond]

Again, thank you all for the suggestions.

I've once again tweaked the legs to a 26" base. Given the weight of the table and the leg construction, I feel more confident that this won't be anywhere near a "tipping" hazard.

Mike - regarding the fixed base: this is the customer's insistance. He does not want to have to move the table across his new hardwood floors. The equalizer slides are also at his request.

I've seen numerous double-pedestal extension tables with a fixed base. Most of them, however, have a lower stretcher. Given the wider base and the top stretcher, I am not too concerned about the lower stretcher.

Then, once you decide on a fixed base, seems to make sense for the pedastal tops to be wider, rather than narrower, in order to support the slides. I guess you could have a narrower pedestal at the top with the slides just attached to the top, but then the top would also have to be attached somehow to the pedestals (sliding dovetail, maybe?).

I think I'm settled on the design, now with the wider base. I'll post pictures.

Again, thank you all for your very helpful comments!

[simeond]

So I am finally coming up on the finishing of this large table. It was DEFINATELY NOT without it's challenges!

I wanted to reply briefly with some observations regarding the pedestal design. First, I ended up with a 24" base for each pedestal (36" at the top). What I found was, because of the curve in the legs, I could go a little narrower than a pedestal that was perpendicular to the floor. This is because with a 90 degree pedestal, the pivot fulcrum is right at the edge I the base. Downward pressure on the overhumg top would cause the table ti tip right on the edge of the base thus the need for a wider base and less overhang. But with the curved legs, there is pressure that runs up the leg before it will tip at it's corner.

Not sure if thy makes sense. Overall I was suprised by the strength and stability, especially considering how light each pedestal is. I guess it's all about directionally distributed weight. I'll post pictures when u finish finishing tomorrow or Friday!

Thanks again everyone for the suggestions!

[eric71m]

I like your design and am anxious to see the final product!

[simeond]

Hey Eric:

The table is finally complete. You can see it in the "Critique Room." Thanks!