[pianotech] Square Grand Hammer Boring Angles

[John Ross]

I did one hammer replacement on a square grand 30+ years ago, and swore I would never do another.
The felt had to be trimmed on two opposite edges, so that they wouldn't interfere with their neighbour.
If I ever did one again, I think that having the hammers recovered would be the way to go.
Abel is one hammer seller that offers that service. I do not know of an American supplier who offers that service.
You would probably still have to trim the felt, but at least the hammer angle would be right.

Was nothing written down about how the trimming was accomplished when these pianos were built?

Definitely not a job for a novice.

Joe Goss probably has some insight as to the proper procedures.

John Ross,
Windsor, Nova Scotia
On 2012-10-29, at 8:42 AM, Terry Farrell <mfarrel2 at tampabay.rr.com> wrote:

> I have a new set of hammers custom made for my 1867 S&S square grand. I think the hammer boring angles are not correct.
> 
> I'm not sure what the proper term may be, but for clarity and reference purposes I will be using the term "hammer diameter axis". By hammer diameter axis, I am referring to one of three axes of the hammer: strike point to tail (height); thickness (self-explanatory - about 9 mm thick); and diameter (shoulder to shoulder) - so the hammer diameter length will vary from maybe 1-1/2" in the bass to about 1/2" in the high treble. I hope that is clear.
> 
> To the best of my knowledge, it seems to me that the hammer boring for an American square grand piano should result in the diameter axis of each hammer either being parallel to its respective string(s), or if not parallel, then purposely angling the hammer diameter axis a few degrees toward parallel with the hammer shank. Is that correct? Should hammers be bored so that there is always some appropriate bias toward the hammer diameter axis being more parallel with the hammer shank?
> 
> On the set I have, the bass hammers are close to parallel with their respective bass strings, but starting in the low tenor and going up the scale, the hammers start to diverge from being parallel with their respective strings, but the deviation from parallel with the respective strings is toward the diameter axis of the hammer being perpendicular to the hammer shank - not parallel with the hammer shank. I'm sure you can easily imagine what kind of hammer clearance problems that produces.
> 
> I'd just plug the entire set and rebore them, but I don't think my Renner hammer boring jig will accommodate square grand hammers - and besides, I've already chewed the heck out of the bass hammers trying to get them to clear their neighbors.
> 
> Looking for a reality check here.......  :-(
> 
> Terry Farrell


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