Steinway casters orientation

[Cy Shuster]

OK, so the force goes through an angle.  Notre Dame still stands with the
flying buttresses, eh?  Time to check assumptions:

1.  The top of the caster is mounted in the center of the leg.
2.  The caster pivots around a vertical axis that is coaligned with the
center of the leg.

As long as this is true, isn't what happens below irrelevant, as long as its
distance to the floor doesn't change?  Sure, there are two arms angling
downward that support the axle.  Are you saying that those arms sag under
the weight, so that if the casters are turned to face each other (caster
axles aligned fore and aft with the keys), then the ends of the legs splay
out away from each other?

If the legs curve out under load, then... well, I still don't get it.  I
guess I'm assuming a point contact at the top of the leg, too.

Draw me a picture when I see you at the chapter meeting tomorrow... and use
small words.. :-)

--Cy "mountain out of a molehill" Shuster--
Rochester, MN

----- Original Message ----- 
From: "Conrad Hoffsommer" <hoffsoco@martin.luther.edu>
To: "Pianotech" <pianotech@ptg.org>
Sent: Friday, January 16, 2004 9:49 AM
Subject: Re: Steinway casters orientation


> At 08:59 1/16/2004 -0600, you wrote:
> >What is the mechanical reason that the caster orientation has an effect
on
> >keyframe bedding?  Is it simply that different orientations cause the leg
to
> >be slightly longer or shorter?
> >
> >--Cy Shuster--
> >Rochester, MN
>
> Cy,
>
> Think vector.
>
> The force of the weight of the piano is not directly through the
centerline
> of the leg, rather is offset the distance which the particular caster axle
> is from that centerline. The greater the distance, like those large brass
> double casters, the more pronounced the effect.
>
> Longer or shorter problem would only be present if axis of the vertical
> axle is other than perpendicular to the floor.
>
>
>
> Conrad Hoffsommer - Music Technician
> Luther College, 700 College Dr., Decorah, Iowa 52101-1045
> Vox-(563)-387-1204 // Fax (563)-387-1076
>
> - Education is what you get from reading the small print. Experience is
> what you get from not reading it.
>
> _______________________________________________
> pianotech list info: https://www.moypiano.com/resources/#archives
>