[CAUT] Hammer Alignment

[Overs Pianos]

Hi Jon,

You're certainly not crazy. This stuff really happens.

I've noticed that shanks can move after a careful setup also. I've 
suspected for a while that it may be caused by the settling out of 
internal growth stresses, which occur over the first year or two, 
causing the burning angle to change.

Always with new pianos, there is a tendency for more movement in the 
first year. The full regulation at the first year usually involves 
quite a deal of hammer alignment. The reg' at year two, considerably 
less. Thereafter, annual reg's will require burning angle adjustment 
of only a couple of hammers.

I think two factors are a play here.

Firstly, the above mentioned stress relieving as the shank ages, and 
secondly the operation of hanging the hammers, and in particular the 
casting to adjust the burning angle.

It is just about impossible to hang a set of hammers which require no 
post-casting to adjust the burning angle. I believe it is important 
to try and hang the hammers such that there is a minimum of casting 
required to set the burning angle afterwards. The important and 
mostly overlooked first step, is to get the shank travel as good as 
possible before the hammers are hung. This will allow us to hang the 
hammers in such a manner as to reduce post-casting requirements 
dramatically. Furthermore, when gluing the hammers, I don't try to 
glue the hammers so that they look nice and parallel initially. I set 
each hammer initially vertically, then check the burning angle by 
moving the shank upwards and visually checking the burning angle 
while the glue is wet. If necessary I'll adjust the angle of the head 
to eliminate a burning angle problem. This is important. The 
requirement to angle the hammer indicates that there is travel error 
at the flange which wasn't eliminated before the hammers were hung. 
If the hammer angle, for each, is adjusted while the glue is wet to 
eliminate the burning angle, the final hammer alignment can be 
achieved after the set is hung by packing the offending hammer 
flanges to correct the travel problem. This approach greatly reduces 
the need for casting the shanks all over the shop after the hanging 
is done, and will significantly reduce those problematical alignment 
stability problems that you have mentioned. The casting operation 
itself requires bending the shank to somewhere that it wasn't sitting 
at previously, when in a state of zero external stress. There is 
always a slight tendency for heat-bent wood to spring back some, over 
time. Therefore, less casting results in greater long term stability.

I have also found that when casting is required, a more stable result 
is achieved if the shank is cast a little too much, then cast back a 
little to where we want it.

A well hung set of hammers can make the job of the touch and tone 
regulator so much easier. Getting on top of the skills required to 
hang a set of hammers is very satisfying. But the learning seems to 
continue on. That's another of life's little pleasures.

Ron O.

>Is it just me or am I crazy but I've noticed a misalignment
>of hammers after a year or two.  By this I mean that the
>hammer has leaned towards the treble such that it requires
>re-setting.  Angled too much for burn-in.
>
>Could it be that the shanks develop a twist, warping
>in a clockwise rotation as viewed from the front?
>Gravitation whiplash from the rotation of the earth?
>
>The travel is not the culprit. When installed, they were dead on.
>I've noticed this developing more so on Renner shanks than Abel.
>It's disconcerting to find your laborious efforts gone astray.
>
>They're not bored off center. I can't recall ever finding
>ones that leaned counter-clockwise.  Oddly enough,
>the bass doesn't seem to exhibit this phenomenon.
>
>A newish M needs most of the top two treble sections reset.
>Yesterday I reset at least a dozen on an L which had new h/s/f
>three years ago.
>
>One could past it off as a poorly hung set
>but I know that was not the case.
>--
>
>Regards,
>
>Jon Page


-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
_______________________

Web http://overspianos.com.au
mailto:ron at overspianos.com.au
_______________________