reducing hammer weight

[William Monroe]

Hi Nick,

Thanks for the info.  Well, I got the hammer weight down where I want it. 
Friction was an issue as well.  The scenario is a '50s "S" with six leads in 
the bass for starters.  Replaced old S/F (15.5mm) with new HSF (17mm knuckle 
spread) tapering the hammers to bring them down close to around a top-low to 
1/4 medium Strike Weight Zone.  Action ration was about 5.8, now is about 
5.2.

Everything else on the action is just refurbished.  Polish key pins, new 
bushings, rail felts, resurface backchecks, and so on.  Bushings were part 
of my problem.  The rail pins were .142 on the FR, and .145 at the BR 
(?!?!).  I ended up using a .143 caul with a relatively loose fit of felt on 
the FR (brass) and .147 on the BR with a relatively tight fitting felt.  The 
BR worked out well, but the FR was tighter than I thought.  Once I ironed 
the felt again, I reweighed and started pulling leads. It still has more 
than I'd prefer, but it is a budget job and we've really made some 
improvements.

New Repetitions in the future would help in the friction dept. as well, I'd 
think.

Also, would you mind expanding upon your last paragraph below??

Thanks,
William R. Monroe



> Hi William,
>
> Although you haven't stated it explicitly, I am guessing that your reason
> for reducing hammer weight is to change touchweight (to lesson the
> downweight from, say, 58 grams to something like 50 or 52). Is that so?
>
> Perhaps you could supply us with a bit more information. For example:
>
> 1) Any idea what your action ratio is? For example, if it is 5 to 1, then
> you would need to remove 1 gram from the hammer in order to reduce the
> downweight by 5 grams, which ties in to JD's (see below) very useful 
> rundown
> of the math.
>
> 2) Can we assume that friction is not an issue?
>
> It may be that there are other ways, perhaps in addition to standard 
> hammer
> weight prepping (i.e., side tapering, tailing and coving) that require
> attention in order to "fix" the touchweight.
>
> Drilling holes in hammer moldings in order to insert weights is an 
> entirely
> different thing than drilling to lower weight/mass. However, drilling 
> holes
> in order to adjust tone, e.g., to tone down the "woody effect" of treble
> hammers is something else and at times has merit.
>
> In addition, our statically determined weight adjustments, i.e., the usual
> downweight/upweight gram tests, is one thing; but the dynamic result of a
> hammer of either more weight or less weight flying toward the strings at
> high velocity is something else again. The dynamic inertial values are a
> function of the static, but are of significantly higher magnitude.
>
> Regards,
>
> Nick Gravagne, RPT