Pedestal table stability

[alex grams]

Does anyone have any experience or rules of thumb about making single central leg pedestal tables and their stability? I have a design and it flares into 4 feet at the bottom (in a cross pattern), each 10" long from the center. The table top is 29.5" off of the ground, and is 45"x35". What are some things i should look for to ensure stability. I really don't want the table to be top heavy or unstable.


Thanks in advance.

[Sam Yerardi]

Did you mean 10" from the center? At 10' I wouldn't think you would ever have a problem.

[alex grams]

yes. while the 10' would be very stable, it would prove difficult to pull a chair up close enough, plus keep tripping everyone in the kitchen. :)

[Sam Yerardi]

That being the case I guess the simplest answer is to determine where the center of gravity is for the table. If that point can fall outside the diameter encompassed by the spread of the legs by more than some minimal amount, say 6" off center, then you might have a problem. I'm not sure if my answer made sense.

[alex grams]

It makes sense, i just didn't want to sit down and calculate centroids and centers of gravity, it will be tedious but simple. I have it modeled in sketchup, but unfortunately that doesn't calculate centers of areas/volumes from what i can see.

[Sam Yerardi]

Pragmatically the way you would do it if you had the physical table in front of you is to suspend it from one point, make note of where the plumb line falls, then suspend the table from another point, make note of where the plumb line falls. Do this at several points. Where the plumb lines cross is the center of gravity. Another way is to break the table into rectangular objects but this method I believe will require the assumption that the density of all the material is the same. Find geometrically the center of mass of each rectangle. Then you can use these points to find the resultant point of all the rectangles together. I would envision the top as one rectangle, the column as another, and the leg system as the other.

[alex grams]

The VCG calculation is simple enough if you simplify the shapes (and they are all the same material).

The question though, is how much side force at the table top should a table be able to handle before stability becomes an issue.

Time to take my bathroom scale and push on some stuff to see how much i could expect to exert.

Or, maybe i am making this too complicated.

[Sam Yerardi]

I don't think you're over complicating it. I was reading about million dollar law suites today on faulty table design that resulted in deaths so it's a worthwhile subject to look into. One benchmark might be to consider the heaviest person that could sit at the table and lean on it. There is undoubtedly a government standard on it with respect to product testing. You could check with product safety information sources in your state.

[Mike McCann]

I have built 60" round poker table with a 10" pedestal. I monted the pedestal on 2' x 2" piece of plywood and then monted this to the bottom of the table this was plenty secure. I also belong to a poker table making forum and the have a lot of great info on mounting pedestals to tables. I will pm you the forum address.