[CAUT] hammer line

[Mark Cramer]

Thanks Alan,

You've triggered a great discussion here! I guess next week we can bat this
around and some other things too. I'm really looking forward to the visit,
and should arrive in Centralia by about 7:00PM Wed. (I actually shortened
the plane part of the trip, so I could take the last part by train) 
 
In any case, I fully understood and appreciate your thread, and all the
excellent contributions so far. BTW, the "he" I referred to, replying to
Ric, was the parts supplier.

At the moment, I'm looking at an action from a 70's D with hammers at strike
lengths varying anywhere from 5" @ 88 to 5 1/8" section to section. You can
imagine the care I took listening, measuring and assessing this action
before bringing it into the shop! ;>)

I think it's accurate to say, like most of us, more than half our rebuilding
jobs are "re-rebuilding." The previous work on an "A" that went out this
morning, was, well, barely broken in. (shame to have to move knuckles before
the factory glue was fully cured, and did they know why new wippens are
numbered, and is there ever a good reason for a second layer of let-off
punchings... etc. !? ;>)

So, in the larger discussion, I just want to be sure that everyone reading
(including myself) has a full picture of all the considerations that go into
altering an action, how much impact to expect from certain modifications,
and how to weigh out the compromises. Most of all, that when we start
weighing/charting "one" variable in .1g increments, that we're not actually
sweeping all the other variables under the carpet.

Otherwise, just imagine all the re-re- action jobs that are going to be
sitting on our benches in a year or two! ;>)

Best regards,

Mark Cramer,
Brandon University
 
-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Alan
McCoy
Sent: February 19, 2008 6:44 PM
To: College and University Technicians <caut at ptg.org>
Subject: Re: [CAUT] hammer line

Mark,

This discussion began with the hammer line being altered for better tone. I
didn't make any adjustment for the weight change. No doubt there is a
noticeable change in weight felt at the key. That'll have to wait for the
next time I'm at the piano.

Alan


> From: Mark Cramer <cramer at brandonu.ca>
> Reply-To: "College and University Technicians <caut at ptg.org>"
<caut at ptg.org>
> Date: Tue, 19 Feb 2008 16:57:04 -0600
> To: 'College and University Technicians' <caut at ptg.org>
> Subject: Re: [CAUT] hammer line
> 
> Hi Ric,
> 
> I think what he means, is if you add 3mm (for instance) to the bore of
> hammers at some point along your strike line, the bulk of the hammer's
mass
> (the big felt part) is now further from the pivot point.
> 
> This has to affect MOI. As my good friend Stan Kroeker suggests, when you
> move the weight up or down on an old metronome, it certainly seems to have
a
> measurable (predictable) effect on the speed.
> 
> The same would be true for curving the line by moving hammers
further/closer
> to the center-pin.
> 
> So, while I'm enjoying the exchange of good methods for measuring strike
> weight, sorting, thinning shanks etc., I'm struggling with the concept of
> sorting shanks over .1 gram difference, distributed who-knows-where along
> it's length, but moving a 4-10g hammer in/out by several mm and not
> accounting for it. (!?)
> 
> If I've missed this in the discussion, please (anyone) feel free to "tune
me
> in," either on, or off-list.
> 
> I'm in favor of the pursuit, but just need to know that we are aware of
and
> dealing with "all" the variables.
> 
> BTW Ric, thanks for the spreadsheet, it's a good working tool!
> 
> Best regards,
> Mark Cramer,
> Brandon University
> 
> 
> 
> -----Original Message-----
> From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of
> Richard Brekne
> Sent: February 15, 2008 3:25 PM
> To: caut at ptg.org
> Subject: [CAUT] hammer line11
> 
> 
> Now this is an interesting concept.  How does altering the bore length
> to match string height variances move the mass farther out on the arc...
> and how does this in turn add up to a more serious problem then the at
> least two biggies I can see it corrects ?
> 
> Cheers
> RicB
> 
> 
>     So, if the strike line you set "by-ear" ends up being a little
>     crooked, and
>     uneven string height is the culprit, why not vary the bore-length?
> 
> 
>     A wise and valued supplier who I turn to for pre-hungs when things get
>     "bizzy," will not do this for me. His claim being that moving mass
>     further
>     in/out on the arc will have more detriment than anything I'm trying to
>     correct.
> 
>      
> 
>