Alan E wrote:
Upon first reading, I thought you had migrated into giving relationship advise. But now your spellcheck has got me wondering if I haven't been compassionate enough when installing agraffes (or perhaps TOO compassionate?)...That would be 'advice', not 'advise', AND, as I reread YOUR post, I see that the conundrum you find yourself in could easily be conveyed as "over-torqued", (at least poetically). Or, if you were a less
sensitive soul, it might describe the energy expended in your
feeling compassion. In any case, I think this aspect of the has now been over talked.
Seriously, the most recent previous thread on agraffes I found was
" agraffes troubled years at Steinway" Oct 11, 2015 11:22 PM Dan Amihud . :
I recently came across the "Agraffes troubled years at Steinway" thread. My good friend & colleague Isaac Sadigursky has alerted me a while ago to this very subject, which originally appeared in a March 1989 PTG journal article. Unfortunately I don't have the author's name available at this moment. The years were 1925 - 1929 Serial numbers: 235,000 - 265,000The article he references was by Susan Graham, as part of her NAMM Update. Hopefully, the Journal will overlook the inclusion of this section, below. If not, I assume they can have it deleted:
Susan Graham - Piano Technicians Journal - March 1989
The final item is more information from Isaac Sadigursky, this time regarding agraffes. Isaac and Kermit Williams of Santa Barbara have put their heads together and formed a theory about the cause of broken agraffes in older Steinways. The problem, Isaac writes, occurs in grands in the serial number range
230,000 - 265,000. They have observed that the broken ones they remove are not threaded completely to the top of the shank (note difference between broken and and intact samples in fig. 3). This would mean that in installation, the worker had to force the part, essentially jamming it in place and stressing the brass. Isaac’s letter was accompanied by several examples of this, including some treble agraffes in which the portion which is drilled for the strings is noticeably bent. He also supplied the model for
Our cover this month, which comes from an A, #242800. As you can see, the head of the agraffe has separated from the shank; it was not yet broken, but was the cause of several callbacks due to unisons
going out of tune.
As Isaac so eloquently remarks, “The painful experience happens when those grands go through the process of restoration and restringing. Maybe a few break in the shop and get replaced and a few years later the old original agraffes start to break and jump like popcorn. This leaves the technician with a dilemma whether to back up his promises and take the piano back into the shop Figure 3 and restring the bass and tenor sections after replacing all the agraffes, or go through court being called a defendant.
(Who needs it!)”
Who needs it, indeed. Many of us who restring routinely replace all agraffes to obtain a clean-edged, round hole at the termination point. However, those of us using a counterbore or an end mill to remove material from the underside of the head had better beware that we don’t recreate the same problem
by exposing a relatively large portion of unthreaded shank and then forcing it into the threads in the plate. Carefully reaming the top l/16” of the hole (by hand, with the appropriate size drill bit) will permit continued use of the end mill style of agraffe installation. Once again, we are all in Isaac Sadigursky and
Kermit Williams’ debt-and I would be interested to hear any more thoughts on the subject. This should not be taken as a particular indictment of Steinway, incidentally-all manufacturers (not to mention every one of us) are capable of creating problems which may not surface for many years. And that’s why the
world needs service technicians.
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David Skolnik
Hastings-on-Hudson NY
914-231-7565
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Original Message:
Sent: 01-23-2017 14:45
From: Alan Eder
Subject: Agraffe Torque
David S. wrote:
"...(over) torqued in the process of compassion?"
Upon first reading, I thought you had migrated into giving relationship advise. But now your spellcheck has got me wondering if I haven't been compassionate enough when installing agraffes (or perhaps TOO compassionate?)...
Alan
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Alan Eder, RPT
Herb Alpert School of Music
California Institute of the Arts
Valencia, CA
661.904.6483
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Original Message:
Sent: 01-21-2017 16:31
From: David Skolnik
Subject: Agraffe Torque
I don't have the tools to experiment currently, but perhaps you do. How will this new found knowledge affect the way you install agraffes going forward? How many agraffes would you need to break before you had what you felt to be a reliable consistency? How many degrees of rotation is represented by the difference between finger snug and 60% of breakage? What if you were to attain proper alignment with only 40%, or 30%? How might a torque measurement of a bolt that is simply right in its particular bored hole be didn't from a bolt with a running fit (as per agraffes) that is (over) torqued in the process of compassion?
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David Skolnik
Hastings-on-Hudson NY
914-231-7565
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Original Message:
Sent: 01-21-2017 13:51
From: Chris Chernobieff
Subject: Agraffe Torque
So i finally looked in the machinist handbook. In it, is a chapter entirely on torque. Believe it or not it's a little more complicated than you first would think. Here are a couple of points i found to be interesting.
Tightening Bolts pg. 1495 Edition 27 Machinery's Handbook
"Bolts are often tightened by applying torque to the head or nut, which causes the bolt to stretch. The stretching results in bolt tension or preload, which is the force that holds a joint together."
pg.1496
"The proper torque to use for tightening bolts in sizes up to 1/2" may be determined by trial (Kudos Wim). Test a bolt by measuring the torque required to fracture it. Then use a tightening torque of about 50 - 60% of the fracture torque determined by the test."
So there you go, much more useful than criticizing.
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ChrisChernobieff
Chernobieff Piano and Harpsichord Mfg.
Lenoir City TN
865-986-7720
chrisppff@gmail.com
www.facebook.com/ChernobieffPianoandHarpsichordMFG
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Original Message:
Sent: 01-21-2017 12:56
From: Benjamin Sloane
Subject: Agraffe Torque
You go by feel and have the patience to moderate with washers. I.e. back it out and add a washer or take one away. I admit that solution to be unsatisfactory after having to ream out broken ones. A torque # needs to be piano specific. The tendency is to overtighten. The front uniplex duplex triplex bearing creates thousands of problems. Probably busted agraffes have less to do with it...
There can't be a universal standard because of the whole menagerie of front duplex design.
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Benjamin Sloane
Cincinnati OH
513-257-8480
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Original Message:
Sent: 01-21-2017 12:21
From: David Skolnik
Subject: Agraffe Torque
This might be a viable alternative, but it begs, or sidesteps the question and poses one or two new ones, mainly, is there anything fundamentally wrong with either shimming OR reducing shoulders, time and labor aside?
As for the thread subject, Ed's suggested method still leaves open the interpretation of "snug", as in, the difference between 'finger-snug' and 'tool-snug'. The agenda of the subject question seems singularly focused on the issue of agraffe breakage and specifically over-tightening as a possible cause. It could very well be a 'possible' cause, but so what? It might also be attributable to material or manufacturing flaws.
When does an agraffe begin to be 'tight enough'? Is it being proposed that there is an ideal torque from a tonal standpoint? What happens, physically, between 'tight enough' and structural damage? Agraffe threads, agraffe shoulder, plate threads, agraffe head/shank juncture?
Maybe a more useful question would be: how many degrees can you safely 'tool-tighten' an agraffe to get from finger-snug to proper alignment. This is a question that even Ed's method should be able to address?
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David Skolnik
Hastings-on-Hudson NY
914-231-7565
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Original Message:
Sent: 01-20-2017 23:38
From: Edward McMorrow
Subject: Agraffe Torque
I have never measured torque on agraffes, but I have found many Steinways from post WW 1 to have many over tightened ones. When NY went to phosphor bronze alloy agraffes in the late 1960's, they just used the stronger material to over tighten them more!!!
The proper way to install aggraffes is to have a plentiful supply. Thread the proper types into their holes and after lining up all that will turn correctly and be snug, start by removing misaligned ones at one end and swap them out with misaligned ones from the other end of the section until as many come out correct as possible, and then remove the remaining misfit ones and replace them with others from your supply. In other words lather, rinse and repeat as needed. This way you can avoid washers or cutting shoulders.
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Edward McMorrow
Edmonds WA
425-299-3431
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Original Message:
Sent: 01-20-2017 17:07
From: Chris Chernobieff
Subject: Agraffe Torque