Sorry, I should have specified a granite surface plate. An indicator holder
might be ok on a cast iron surface plate.
Bob Swinney
"Robert Swinney" wrote in message
...

"DeepDiver" wrote in message
...
"Dave" wrote in message
ups.com...
Are some of these heavier than others? I want one that absolutely won't
fall over... You can't keep the darned magnet turned on all the time...
unless maybe I should try turning the magnet half on???

Stability has nothing to do with weight (or, more precisely, mass). It
has to do with the center of mass (center of gravity) of an object, and
the forces acting upon it. So a very wide and short, lightweight
indicator stand base will be less prone to tipping over (i.e., more
stable) than a very heavy base that is tall and narrow.

However most mag bases have fairly similar, proportional dimensions
(roughly a square cube). So what you want for max stability is a base
that is dimensionally larger, thus concentrating more mass in the base
than in the arms. Lighter weight arms (e.g., aluminum) will also help to
keep the center of mass low.

Of course, if the arms are extended outward, they will increase the
tipping moment acting on the base, and if they are extended upward, they
will raise the center of mass (thus reducing stability). This negative
effect will increase with increasing mass of the item (e.g., indicator)
being held by the arm.

I'm curious though: why *can't* you keep the "darned magnet turned on all
the time" (except when moving/repositioning the base, of course)? It's
not as if the magnet will wear out or lose strength. You suggested
turning the magnet half-on, so it appears as if you are still placing it
on a magnetic surface. Perhaps you'll find the answer you're seeking if
you were to explain the actual problem that you're having.

- Michael