OK, all you math wizards, here's one for you:
Given a pedestal table with a top diameter of Dtop, a bottom diameter
Dbottom, and a height H, define a function f() such that
Dbottom = f(Dtop, H).
You can assume that the table is symetrical about the center axis.
For all of you non math wizards, what's a good rule of thumb for
how big to make the base of a pedestal end table approx. 20" tall?
I posted the same question not long ago.... Here's the link...
On Wed, 13 Feb 2008 00:50:17 GMT, email@example.com (Mike McDonald)
It's not quite that easy. This is a static (mechanical engineering)
problem about moment arms, center of gravity and the force applied to
the edge of the table. Some round tables are sturdier than others.
I was just talking to a buddy who builds desk lamps commercially. We were
discussing design requirements and he said that the UL requires that a desk
lamp can be tilted 70 degrees without falling over.
No, that doesn't apply to a table, but it gives you a good starting point
(ending point?) for your table design.
In that case none of my UL listed desk lamps are UL listed--70 degrees
is an awful lot of tilt--that's not in the "desk lamp" realm, that's
in the "Weebles wobble but they don't fall down" realm. Heck, I don't
know of any _desks_ that will go that far over without falling, let
along desk _lamps_.
And no, I don't know what the standard says--UL wants more than 300
bucks for a copy of it and then it references a few thousand bucks
worth of other standards.
The physics here is well known: F = ma where m is the mass of the
bottom and a is the angle of the dangle. F is a measure of the
proportionality of the two features held at bay unless it's a goose neck
lamp for which all bets are off. If you are near Philadelphia you must
factor in the fact that all involutory collineations are harmonic
homologies. Hope this helps.
On Feb 12, 5:50 pm, firstname.lastname@example.org (Mike McDonald) wrote:
you can't reduce table design to a single ratio.
it's an end table, not for seating, so that simplifies things quite a
bit, as you don't need to provide foot/ knee space. if the mass of the
base can exceed the mass of the top by a *significant* margin, and the
diameter to height ratio is large enough you can make the base smaller
than the top by amounts that diminish as the ratios get higher, but
unless there is a real need to do so don't bother. do a weighted mock
up with the base an inch or two smaller in radius than the top and see
how it performs in the proposed location.
and watch out for over intellectualizing furniture design. that way
lies some ugly product.
True, but there probably are some good rules of thumb to start with.
Off hand, I'm thinking somewhere around 2/3 the top diameter is a good
compromise between stability and asthetics.
Since these end tables will be surrounded on all four sides by walls or
couches, I can lean more towards asthetics. But since the table is
surrounded, the base won't be seen either. The biggest "impact" on stability
will be "Lead Butt", the cat, springboarding off of it.
I was assuming (unstated) no lead weights. I was thinking strictly of
uniform density wood construction.
So true. The whole part about defining f() was bait for the
"intellectuals" who kept trying to teach me trig when I wanted to
know how to cut an octogon. Practical vs theoretical knowledge.
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