Casters (soft vs hard)

[Jerry Anderson]

>   A "light bulb" just went off in my head and I'm wondering if this bowing
>of the keybed because of the caster position could be the reason I've had a
>problem with the ends of the keyframe knocking on our Hamburg D I asked
>about several weeks ago?
>   The casters were installed several years ago (before I started here).
>I've been here 3+ years and until I started seeing the posts about this
>problem, I had never heard about it. So, obviously, no attempt has ever
>been made before now to leave the casters in the forward/back position.

        We don't consider this to be a big problem in our Hamburg D's.  Its
more like a minute change you can detect if you know when and where
to look for it.  It is most  visible in the regulation of the gliders in the
middle of the keybed.  It's hard to imagine a more or less normal set
of casters deforming a solid keybed under  the cheekblocks enough
to allow knocking.  I think your problem is elsewhere.  Sorry I'm new
to the list and haven't seen the old postings on your subject.
        By the way, I measured a set of Hamburg brass concert casters
today.  The axles are excentric to vertical by 4 cms.

Jerry Anderson