A Brief Rant -- Believe it or Not -- On Table Legs
Last night I was at a wonderful dinner in Sedona (report to follow in a later post). However, at this very nice restaurant, the table wobbled, as tables so often do in restaurants.
Here is my question: Why do restaurants still buy tables with four legs?? I understand in the old style table, where legs were at each corner of the table, four legs facilitates having 1-4 guests at a table without the legs getting in the way. But most restaurants nowadays use tables that have a single pedestal in the middle, that then sits on -- and this is my problem -- four legs. Here is an example:
Why not three legs? Three legs are inherently stable, and in the pedestal design don't have to be any more obtrusive than four. Even if the ground is uneven flagstone, a table with three legs still will not wobble. A table with four legs almost always will.
Stop the madness.
Spas Kolev:
https://en.wikipedia.org/wiki/Redundancy_%28engineering%29 :D
September 29, 2013, 11:10 pmIncunabulum:
What's even weirder - my experience dealing with furniture suppliers for large-scale purchasing has shown me that the supplier is willing to modify stock designs to accommodate your preferences, often for no additional charge.
September 30, 2013, 12:08 amIts just that its probably never occurred to the purchaser that 3 legs might be better than 4.
Incunabulum:
Except that if you lose one leg out of those four you aren't left with a useable table - it'll just fall over.
September 30, 2013, 12:09 amPeter:
In a bar it's because it helps you spill drinks so have to buy more.
September 30, 2013, 1:19 amFrederick Davies:
You do realise that conflict with human feet are not the main problem with table legs, but the legs of the chairs those humans are using. A three-legged table will conflict with the legs of four chairs around it; if you reduce the number of table legs to three, you will have to reduce the number of chairs to three too. That is a 25% reduction in seating capacity.
September 30, 2013, 3:27 amFD
marque2:
I can tell this - three legged tables - especially with the small footprint shown in your photo, are much much more likely to tip. I can can imagine some lawyer in Arizona and his spate of 3 legged table suits.
September 30, 2013, 6:05 amnaturesgrrl:
Good point! Maybe the restaurant didn't have the money to invest in well-built sturdy furniture. It's a low margin business.
September 30, 2013, 6:33 amaczarnowski:
I'm surprised OSHA hasn't mandated five legs per table...
September 30, 2013, 8:18 amNRG:
That is why I love this blog. No stone goes unturned.
September 30, 2013, 9:20 amMW:
I ate lunch at a square, three-legged table the other day. The leg arrangement is guaranteed to collide with the feet of at least one person. It also produces a much less stable table. If you lean on the wrong corner of it, the table is going to tip over.
September 30, 2013, 9:45 amIvarHusa:
Perhaps it is for the same reason office chairs now have 5 legs instead of 4. They are much less prone to tipping over from a heavy weight being placed at the edge, perhaps a large patron leaning on it to arise from their chair.
My proposed solution would be to have a large, circular base that is flat enough not to interfere with foot placement, and large enough in diameter to avoid the tip-over problem. OK, you still have the teetering issue...
September 30, 2013, 10:33 amRick Caird:
When I started working in 1968 an old timer had exactly the same rant. I repeat it from time to time. Three points define a plane. Four points define something else.
September 30, 2013, 11:46 amVangel:
I agree entirely. When I was in the aircraft building business I was impressed by tool designers who figured out that the best solution to a problem of how to construct a massive jig that would be used to manufacture very large aircraft wings was to start with having only three pads that would support all of the weight. Why is it that furniture makers can't use the same approach for exactly the same reason?
September 30, 2013, 12:13 pmTom Nally:
There are two kinds of stability here. The one that Warren is talking about is the tendency to avoid wobbling. But in the structural engineering sense, stability refers to the resisting moment divided by overturning moment. This is called the "overturning factor of safety".
The geometry of the 4-legged table produces a smaller tendency to overturn. To see a graphic demonstration of this, click the link on my wikispaces site. http://nally.wikispaces.com/file/detail/Two_Tables.pdf
So, even though 4-legged tables have a greater tendency to wobble, they are more stable in the structural engineering sense. When I built a 4-legged stool earlier this year, I placed rubber pads under all four legs. These pads "give" when someone stands on the stool. So, all four legs remain in contact with the floor, even if the floor is a little uneven. But I made the stool 4-legged instead of 3-legged because it was inherently more "stable": less susceptible to overturning.
September 30, 2013, 5:49 pmLeroy:
Four points define a pain*
March 10, 2015, 8:56 am