[pianotech] flipping a truck

[Scott Helms, RPT]

It's been so long ago that the original post was put up that I may have
forgotten a couple of details. Are they planning to keep the big casters
on the truck? If so, they are presumably planning to (at some point) push
the whole contraption to wheel it to a different locale. This operation
might be just the one that leads to the "optimal idiot inclination tip
point" Ron mentions, especially if the wheels hit a bump in the process.

The obvious question is, if they're going to go to the trouble of building
a platform to accomodate the bench/pianist and a resting point for the
heels at the pedals, why not just go all-out and build the damn thing big
enough to accomodate the whole piano?? The whole platform could be on
wheels if they wanted it to be movable ... very similar to a wheeled
platform I built to accomodate a 3-manual organ console a few years ago.
It worked great!

Scott
------
Scott A. Helms, Registered Piano Technician
480-818-3871
www.helmsmusic.net






> Israel Stein wrote:
>> Something has been bothering me about this. Wouldn't the center of
>> gravity on a piano mounted on a flipped truck be quite a bit higher,
>> making the whole thing less stable - if force is applied at the wrong
>> place in the wrong direction? Granted, a tripod (which is what we have
>> here) is inherently the most stable configuration, but suppose
>> sufficient upward force were for some reason applied at one of the legs
>> - wouldn't it be possible for the whole thing to tip over along the line
>> formed by the other two legs - given such a high center of gravity? Now
>> I know that this is not likely, but we have here a bunch of ignoramuses
>> doing unpredictable things with a piano...
>
> I'm forever amazed that a profession so filled with -
> recovering - engineers doesn't swamp this sort of question
> with highly educated answers, all in absolute agreement to
> four decimal places. But in the continued conspicuous absence
> of experts, I'll take a non-pedigreed stab at it.
>
> In my world, the center of mass of an assembly has to be
> outboard of it's support for it to tip over. So far, I haven't
> run into an instance where that presumption hasn't proved to
> be a practical guide to preventing things from falling over.
> If a piano on a standard truck has to be tilted at 45°
> (arbitrarily chosen) to tip over, then a piano on a flipped
> truck, supported at a higher altitude, would tip over at a
> lesser degree of inclination, say, 40° or so. Even if it were
> 30°, which is what doing the math instead of speculating is
> for, it would take a pretty spectacular idiot or committee to
> make up the difference. While I have no doubt whatsoever that
> such spectacular idiots and committees exist out there in vast
> numbers, I submit that the difference between a 45° tip point
> and a 40°, or even 30° (math verification pending) is way too
> far past the idiot threshold to be guarded against by a mere
> 5°, or even 15° (pending the math) difference in an
> inclination angle already way past rational (math verification
> impossible). But then there's the question of the legs
> breaking before the optimal idiot inclination tip point is
> achieved, thereby robbing the participant(s) of their due
> glory and immortality, and screwing up the vector calculation.
>
> But Then, I'm not an engineer,
> Ron N
>
>