Pianotech

Tightening up rep levers on a new set of Tokiwa whips. Friction is 1g or even a shy 1g at the drop screw ecsaine. I'd like the friction up around 6-7g, but that means going up from a 20 to a 21 or even 21-1/2 pin. I'd prefer not make such a big jump in pin sizes if avoidable. Any other tricks to increase that friction?

Jim Ialeggio

-------------------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
-------------------------------------------

Jim, This is a timely post, which I will explain, however I'm wondering, first,  why would you not step up to 20 1/2?  Nominally, .050" to .051".  I just happen to be sitting in my shop, having to repin some Renner shanks which were, a few days ago, too tight, and now, even with controlled alcohol/water application, are, in many cases, too loose, so you provided the perfect impetus to experiment.  You should know, additionally, that I had a somewhat tense conversation, earlier today, with a supplier of center pins, after I found that the entire supply of # 20 1/2 pins, which should read at .0510" were more consistently between .0515" and .0518", bringing them only .0020" shy of the nominal size of #21 pins.  Here is the data from my experiment:

Tools used:
Starrett #232  1/2" vernier micrometer (.0001")
P.K. Neuses #N-10 Spring gram gauge (1 - 10 grams)
P.K. Neuses #N-30 Spring gram gauge (1 - 30 grams)

Hammer # 44 - Existing pin (#20?)  Center pin (with .0015" (D) x .030" wide groove in middle).  Pin diameter measures .0506" (rather than .0500").  Friction measured 1 gram at rear of flange  - 18 swings

Replaced with #20 1/2 pin (nominally .0510") which actually measured .0515" and produced a resistance of 20 grams (without any action center reaming or burnishing).  

Hammer #45 - Existing pin as above (#20?) measuring .0507".  1 gram friction w/ 18 swings
Replaced with .0506" WNG (L) pin -(un-burnished/reamed)  
Test swings (each side, prior to reassembling with flange): Right =1 7 swings; Left = 5 swings
Gram resistance reassembled: 10 gr.

What does all this tell you?

-------------------------------------------
David Skolnik
Hastings-on-Hudson NY
914-231-7565
-------------------------------------------


Original Message:
Sent: 07-29-2014 22:08
From: Jim Ialeggio
Subject: Rep lever pinning

Tightening up rep levers on a new set of Tokiwa whips. Friction is 1g or even a shy 1g at the drop screw ecsaine. I'd like the friction up around 6-7g, but that means going up from a 20 to a 21 or even 21-1/2 pin. I'd prefer not make such a big jump in pin sizes if avoidable. Any other tricks to increase that friction?

Jim Ialeggio

-------------------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
-------------------------------------------

David, would you be so kind to explain your 'controlled alcohol/water application' process? I've had mixed results myself, and I am curious of the method of others.

Thank you.

-------------------------------------------
-Phil Bondi
-------------------------------------------

I've had pretty good luck (not perfect) by pinning 2-4 g too tight and then sequentially treating with straight ethanol (minor reduction or even slight tightening), then 5% water in ethanol, then 10%, and then 15% as needed. I use as little as possible to completely wet the bushing and allow at least four hours (overnight is better) of drying time between applications. The result is very firm bushings with the correct friction and little to no "ratcheting" motion of the flange. It definitely takes longer than just reaming/burnishing to the desired friction.

-------------------------------------------
Benjamin Rocke
Piano Technician
Manchester CT
860-533-0311
-------------------------------------------



Original Message:
Sent: 7/30/2014 6:12:00 AM
From: phil@philbondi.com
Subject: RE: Rep lever pinning

David, would you be so kind to explain your 'controlled alcohol/water application' process? I've had mixed results myself, and I am curious of the method of others. Thank you. ------------------------------------------- -Phil Bondi -------------------------------------------

If the idea (as in the original post) is to be able to re-pin with less increase of pin diameter and still achieve a higher friction, one possibility is to unpin, and leave the parts unpinned for a period of time (eg overnight). The felt will "relax" its compression, and when you insert a pin the friction will be higher, even if it is just the same pin you removed. How permanent that is would be subject to question (I don't know the answer, can only speculate. I have left parts apart and repinned, so I do know the bushings tend to do as I describe). It might be more permanent if you could add a modest amount of water the the mix, maybe applying a very weak alcohol and water mix (10:1 or so). These are thoughts I have had, but never had the occasion to need to experiment, so never did. The alcohol and water, in the absence of the pin (to compress the felt against) will simply swell/relax the felt. I guess you could also apply steam, but that would be hard to do in a controlled way.

I avoid thinking in terms of friction alone when it comes to centerpins. That really isn't a very useful gauge of what you have. There could be friction between birdseye and flange, for instance. The felt itself, or the pin, could have a surface or a "contaminant" that causes friction. Often if you lubricate such a center joint, friction virtually disappears.  

"Pinning for friction" can be an exercise in frustration and futility, especially if that is all you look at. (I guess it is different with the WNG parts - I am assuming felt bushings). I like to lubricate every center I pin, so that isn't an issue. Then, when I have achieved a degree of friction, it is more likely to stay put. I also like to burnish the felt bushing hard and fast to achieve the sizing I am after, letting the burnishing take me up a half size (0.001"). Again, this is for stability. Before I started doing these things, I checked my work a week after and found that the meticulous achievement of 4 - 5 gm of friction in every hammer center (up from 1 - 2 gm) had dropped down to, yes, 1 - 2 gm. (At that point I was mechanically removing a bit of felt with the equivalent of Mannino broaches, followed by not so vigorous burnishing as I do now). Frustrating. Wasted time. I hate it.

-------------------------------------------
Fred Sturm
University of New Mexico
http://fredsturm.net
"When I smell a flower, I don't think about how it was cultivated. I like to listen to music the same way." -Federico Mompou
-------------------------------------------


Original Message:
Sent: 07-30-2014 12:08
From: Benjamin Rocke
Subject: Rep lever pinning

I've had pretty good luck (not perfect) by pinning 2-4 g too tight and then sequentially treating with straight ethanol (minor reduction or even slight tightening), then 5% water in ethanol, then 10%, and then 15% as needed. I use as little as possible to completely wet the bushing and allow at least four hours (overnight is better) of drying time between applications. The result is very firm bushings with the correct friction and little to no "ratcheting" motion of the flange. It definitely takes longer than just reaming/burnishing to the desired friction.

-------------------------------------------
Benjamin Rocke
Piano Technician
Manchester CT
860-533-0311
-------------------------------------------

Although the felt might relax and return to a tighter fit, the other issue worth mentioning  is that of the birdseye/centerpin fit. Removing a pin usually always affects the size of the birdseye. Thus going up a 1/2 size for the benefit good fit is almost always in order.
-------------------------------------------
Tom Servinsky
-------------------------------------------


Original Message:
Sent: 07-30-2014 16:21
From: Fred Sturm
Subject: Rep lever pinning

If the idea (as in the original post) is to be able to re-pin with less increase of pin diameter and still achieve a higher friction, one possibility is to unpin, and leave the parts unpinned for a period of time (eg overnight). The felt will "relax" its compression, and when you insert a pin the friction will be higher, even if it is just the same pin you removed. How permanent that is would be subject to question (I don't know the answer, can only speculate. I have left parts apart and repinned, so I do know the bushings tend to do as I describe). It might be more permanent if you could add a modest amount of water the the mix, maybe applying a very weak alcohol and water mix (10:1 or so). These are thoughts I have had, but never had the occasion to need to experiment, so never did. The alcohol and water, in the absence of the pin (to compress the felt against) will simply swell/relax the felt. I guess you could also apply steam, but that would be hard to do in a controlled way.

I avoid thinking in terms of friction alone when it comes to centerpins. That really isn't a very useful gauge of what you have. There could be friction between birdseye and flange, for instance. The felt itself, or the pin, could have a surface or a "contaminant" that causes friction. Often if you lubricate such a center joint, friction virtually disappears.  

"Pinning for friction" can be an exercise in frustration and futility, especially if that is all you look at. (I guess it is different with the WNG parts - I am assuming felt bushings). I like to lubricate every center I pin, so that isn't an issue. Then, when I have achieved a degree of friction, it is more likely to stay put. I also like to burnish the felt bushing hard and fast to achieve the sizing I am after, letting the burnishing take me up a half size (0.001"). Again, this is for stability. Before I started doing these things, I checked my work a week after and found that the meticulous achievement of 4 - 5 gm of friction in every hammer center (up from 1 - 2 gm) had dropped down to, yes, 1 - 2 gm. (At that point I was mechanically removing a bit of felt with the equivalent of Mannino broaches, followed by not so vigorous burnishing as I do now). Frustrating. Wasted time. I hate it.

-------------------------------------------
Fred Sturm
University of New Mexico
http://fredsturm.net
"When I smell a flower, I don't think about how it was cultivated. I like to listen to music the same way." -Federico Mompou
-------------------------------------------


Original Message:
Sent: 07-30-2014 12:08
From: Benjamin Rocke
Subject: Rep lever pinning

I've had pretty good luck (not perfect) by pinning 2-4 g too tight and then sequentially treating with straight ethanol (minor reduction or even slight tightening), then 5% water in ethanol, then 10%, and then 15% as needed. I use as little as possible to completely wet the bushing and allow at least four hours (overnight is better) of drying time between applications. The result is very firm bushings with the correct friction and little to no "ratcheting" motion of the flange. It definitely takes longer than just reaming/burnishing to the desired friction.

-------------------------------------------
Benjamin Rocke
Piano Technician
Manchester CT
860-533-0311
-------------------------------------------

>What does all this tell you?

That you're being far too critical?

:-)

-------------------------------------------
Regards,

Jon Page

<David S why would you not step up to 20 1/2?  Nominally, .050" to .051".

20 up to 20 1/2 doesn't increase the friction adequately. only moves it to 3g or so. It took a nominal move from .049 to .052 to reach target. As I said the pinning was very loose, less than 1 gram measured at the end of that long rep lever. I don't like stepping up that much, because I don't like the parts to start life with a big pin, and I don't like forcing a .052 pin into the existing birdseye.


<What does all this tell you?

That pinning is a pain in the ass.

Also, that if you observe, as you are, how inaccurate all the parts are, including the out of plane drilling of the birdseye/bushing holes, that stable accurate pinning is a complete fiction. Aim for a general target and don't get too picky, because it will change. It will function within a pretty large window,  but it will never retain serious accuracy.

My interest in the rep friction is a function of repetition and checking. 1 gram is outside the window, in my opinion.

Jim Ialeggio   


-------------------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
-------------------------------------------


Original Message:
Sent: 07-29-2014 23:56
From: David Skolnik
Subject: Rep lever pinning

 I just happen to be sitting in my shop, having to repin some Renner shanks which were, a few days ago, too tight, and now, even with controlled alcohol/water application, are, in many cases, too loose, so you provided the perfect impetus to experiment.  You should know, additionally, that I had a somewhat tense conversation, earlier today, with a supplier of center pins, after I found that the entire supply of # 20 1/2 pins, which should read at .0510" were more consistently between .0515" and .0518", bringing them only .0020" shy of the nominal size of #21 pins.  Here is the data from my experiment:

Tools used:
Starrett #232  1/2" vernier micrometer (.0001")
P.K. Neuses #N-10 Spring gram gauge (1 - 10 grams)
P.K. Neuses #N-30 Spring gram gauge (1 - 30 grams)

Hammer # 44 - Existing pin (#20?)  Center pin (with .0015" (D) x .030" wide groove in middle).  Pin diameter measures .0506" (rather than .0500").  Friction measured 1 gram at rear of flange  - 18 swings

Replaced with #20 1/2 pin (nominally .0510") which actually measured .0515" and produced a resistance of 20 grams (without any action center reaming or burnishing).  

Hammer #45 - Existing pin as above (#20?) measuring .0507".  1 gram friction w/ 18 swings
Replaced with .0506" WNG (L) pin -(un-burnished/reamed)  
Test swings (each side, prior to reassembling with flange): Right =1 7 swings; Left = 5 swings
Gram resistance reassembled: 10 gr.


-------------------------------------------
David Skolnik
Hastings-on-Hudson NY
914-231-7565
-------------------------------------------


Original Message:
Sent: 07-29-2014 22:08
From: Jim Ialeggio
Subject: Rep lever pinning

Tightening up rep levers on a new set of Tokiwa whips. Friction is 1g or even a shy 1g at the drop screw ecsaine. I'd like the friction up around 6-7g, but that means going up from a 20 to a 21 or even 21-1/2 pin. I'd prefer not make such a big jump in pin sizes if avoidable. Any other tricks to increase that friction?

Jim Ialeggio

-------------------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
-------------------------------------------

Jim -
I agree with you about the desire for firmer pinning at the rep lever.  I don't think the actual number is as 'critical' there as at the hammer flange.  I also agree as to the general location of the pain.  In spite of the acknowledge imprecision, I think it's worth trying to assess, as much as possible, WHERE the lack of control resides.  When I point out the discrepancies between nominal and actual center pin sizes, that doesn't mean I intend to sit here in a trance until such time as someone supplies the perfect product, but it does (I think) need to be a part of the conversation... to wit: the results I previously reported seemed counter-intuitive, where, in the first instance, I got dramatic (read 'excessive') increase in friction by going up a half size, and, in the second instance, only slightly excessive results by replacing with a pin that actually measured .0001" smaller.   This morning, sample one is measuring 12-14 grams, and #2 is 6 grams.

Apart from confirming your own underlying contention regarding where it hurts, and Jon Page's (and your) assessment of where I fall on the picky meter, I think it tends to reconfirm the observation that consistency and production 'efficiency' are not always equally achievable.

You're trying to find a faster method to achieve a more consistent (or at least desirable)  result.  I'd be interested to know if such an option is available as well.  Meanwhile, to indulge for a moment in 'picky', (rhetorically) WHY are these parts coming pinned this way?  Is this what the manufacturer intended?  Based upon what set of criteria?

More pinning today.  I'll take more notes. 



-------------------------------------------
David Skolnik
Hastings-on-Hudson NY
914-231-7565
-------------------------------------------


Original Message:
Sent: 07-30-2014 07:27
From: Jim Ialeggio
Subject: Rep lever pinning

<David S why would you not step up to 20 1/2?  Nominally, .050" to .051".

20 up to 20 1/2 doesn't increase the friction adequately. only moves it to 3g or so. It took a nominal move from .049 to .052 to reach target. As I said the pinning was very loose, less than 1 gram measured at the end of that long rep lever. I don't like stepping up that much, because I don't like the parts to start life with a big pin, and I don't like forcing a .052 pin into the existing birdseye.


<What does all this tell you?

That pinning is a pain in the ass.

Also, that if you observe, as you are, how inaccurate all the parts are, including the out of plane drilling of the birdseye/bushing holes, that stable accurate pinning is a complete fiction. Aim for a general target and don't get too picky, because it will change. It will function within a pretty large window,  but it will never retain serious accuracy.

My interest in the rep friction is a function of repetition and checking. 1 gram is outside the window, in my opinion.

Jim Ialeggio   


-------------------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
-------------------------------------------


Original Message:
Sent: 07-29-2014 23:56
From: David Skolnik
Subject: Rep lever pinning

 I just happen to be sitting in my shop, having to repin some Renner shanks which were, a few days ago, too tight, and now, even with controlled alcohol/water application, are, in many cases, too loose, so you provided the perfect impetus to experiment.  You should know, additionally, that I had a somewhat tense conversation, earlier today, with a supplier of center pins, after I found that the entire supply of # 20 1/2 pins, which should read at .0510" were more consistently between .0515" and .0518", bringing them only .0020" shy of the nominal size of #21 pins.  Here is the data from my experiment:

Tools used:
Starrett #232  1/2" vernier micrometer (.0001")
P.K. Neuses #N-10 Spring gram gauge (1 - 10 grams)
P.K. Neuses #N-30 Spring gram gauge (1 - 30 grams)

Hammer # 44 - Existing pin (#20?)  Center pin (with .0015" (D) x .030" wide groove in middle).  Pin diameter measures .0506" (rather than .0500").  Friction measured 1 gram at rear of flange  - 18 swings

Replaced with #20 1/2 pin (nominally .0510") which actually measured .0515" and produced a resistance of 20 grams (without any action center reaming or burnishing).  

Hammer #45 - Existing pin as above (#20?) measuring .0507".  1 gram friction w/ 18 swings
Replaced with .0506" WNG (L) pin -(un-burnished/reamed)  
Test swings (each side, prior to reassembling with flange): Right =1 7 swings; Left = 5 swings
Gram resistance reassembled: 10 gr.


-------------------------------------------
David Skolnik
Hastings-on-Hudson NY
914-231-7565
-------------------------------------------


Original Message:
Sent: 07-29-2014 22:08
From: Jim Ialeggio
Subject: Rep lever pinning

Tightening up rep levers on a new set of Tokiwa whips. Friction is 1g or even a shy 1g at the drop screw ecsaine. I'd like the friction up around 6-7g, but that means going up from a 20 to a 21 or even 21-1/2 pin. I'd prefer not make such a big jump in pin sizes if avoidable. Any other tricks to increase that friction?

Jim Ialeggio

-------------------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
-------------------------------------------

Jim I.,

The only real issue I see you avoiding, other than your personal preference in not wanting to go to a larger center pin, is this:
Quoting you, "I don't like forcing a .052 pin into the existing birdseye."

Well, neither do I, and I would suspect several others on this list feel the same way about such an approach. Who wants to break parts causing even more work  :-(

So, why force. there is a reamer tool specifically designed for enlarging the birds eye as needed to accommodate a larger center pin.

Doesn't really take that much more time to complete the necessary re-pinning process.

Keith McGavern, RPT
Shawnee, Oklahoma, USA
kam544@allegiance.tv
[Visual Tuning Platform User]
[iRCT & OnlyPure ]

Original Message:
Sent: 07-30-2014 07:27
From: Jim Ialeggio
...   I don't like stepping up that much, because I don't like the parts to start life with a big pin, and I don't like forcing a .052 pin into the existing birdseye.  ...

Ended up .053 instead of .052. Put a .0515 pin in a hand drill, ran it backwards to ream/burnish the birdseye.

Jim Ialeggio
-------------------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
-------------------------------------------

Hi Jim,

How have you arrived at your 6-7 gram target for rep lever pinning?

Thanks.

-------------------------------------------
Alan McCoy
Spokane WA
ahm2352@gmail.com
-------------------------------------------


Original Message:
Sent: 07-30-2014 07:27
From: Jim Ialeggio
Subject: Rep lever pinning

<David S why would you not step up to 20 1/2?  Nominally, .050" to .051".

20 up to 20 1/2 doesn't increase the friction adequately. only moves it to 3g or so. It took a nominal move from .049 to .052 to reach target. As I said the pinning was very loose, less than 1 gram measured at the end of that long rep lever. I don't like stepping up that much, because I don't like the parts to start life with a big pin, and I don't like forcing a .052 pin into the existing birdseye.


<What does all this tell you?

That pinning is a pain in the ass.

Also, that if you observe, as you are, how inaccurate all the parts are, including the out of plane drilling of the birdseye/bushing holes, that stable accurate pinning is a complete fiction. Aim for a general target and don't get too picky, because it will change. It will function within a pretty large window,  but it will never retain serious accuracy.

My interest in the rep friction is a function of repetition and checking. 1 gram is outside the window, in my opinion.

Jim Ialeggio   


-------------------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
-------------------------------------------


Original Message:
Sent: 07-29-2014 23:56
From: David Skolnik
Subject: Rep lever pinning

 I just happen to be sitting in my shop, having to repin some Renner shanks which were, a few days ago, too tight, and now, even with controlled alcohol/water application, are, in many cases, too loose, so you provided the perfect impetus to experiment.  You should know, additionally, that I had a somewhat tense conversation, earlier today, with a supplier of center pins, after I found that the entire supply of # 20 1/2 pins, which should read at .0510" were more consistently between .0515" and .0518", bringing them only .0020" shy of the nominal size of #21 pins.  Here is the data from my experiment:

Tools used:
Starrett #232  1/2" vernier micrometer (.0001")
P.K. Neuses #N-10 Spring gram gauge (1 - 10 grams)
P.K. Neuses #N-30 Spring gram gauge (1 - 30 grams)

Hammer # 44 - Existing pin (#20?)  Center pin (with .0015" (D) x .030" wide groove in middle).  Pin diameter measures .0506" (rather than .0500").  Friction measured 1 gram at rear of flange  - 18 swings

Replaced with #20 1/2 pin (nominally .0510") which actually measured .0515" and produced a resistance of 20 grams (without any action center reaming or burnishing).  

Hammer #45 - Existing pin as above (#20?) measuring .0507".  1 gram friction w/ 18 swings
Replaced with .0506" WNG (L) pin -(un-burnished/reamed)  
Test swings (each side, prior to reassembling with flange): Right =1 7 swings; Left = 5 swings
Gram resistance reassembled: 10 gr.


-------------------------------------------
David Skolnik
Hastings-on-Hudson NY
914-231-7565
-------------------------------------------


Original Message:
Sent: 07-29-2014 22:08
From: Jim Ialeggio
Subject: Rep lever pinning

Tightening up rep levers on a new set of Tokiwa whips. Friction is 1g or even a shy 1g at the drop screw ecsaine. I'd like the friction up around 6-7g, but that means going up from a 20 to a 21 or even 21-1/2 pin. I'd prefer not make such a big jump in pin sizes if avoidable. Any other tricks to increase that friction?

Jim Ialeggio

-------------------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
-------------------------------------------

Alan M<How have you arrived at your 6-7 gram target for rep lever pinning?

On the advice of others regarding improved repetition. This a first try at upping the friction levels, so its a wait and see. However, in this case, the wait and see will have to wait and see some more, because its not happening on this action. Either these Tokiwa felts are just mushy or the summer humidity is doing its thing, but the strong 7g pinning I set last week is now about 3.5g...and that's where its staying.

This kind of thing is such a strong argument for WNG's parts that when I have to use wood parts for some reason or other, its a real bummer.

Jim Ialeggio

 

-------------------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
-------------------------------------------

-
<David S- take 2 -What does all this tell you?

What you are observing, as far as inconsistent and backwards results, says to me positioning of the pin in the felt is difficult to repeat with the precision required for really precise results. I have had similar experiences. Earlier on, despite very careful tracking of the results and various procedures, results were inconsistent, resistance generally dropped the next day, sometimes continued dropping a couple of weeks later.

This is why, when possible, I would really like to leave the parts assembled and avoid physically messing  with the interface, unless forced to. It is also why I like the alcohol/water sizing technique, which really seem to be pretty generous in the accommodating imprecision department, is so attractive, both in terms of speed and stability(relative stability that is)

For tightening, Chris Brown has a technique that I have not been able to duplicate results on yet, but I have a call into him on it. He sticks a pin into the felt while the pin is installed to increase resistance. He says its somewhat stable...though the word stable has to be taken with a grain of salt, as the next guy who walks into the room with a cup of coffee will change resistance in any felt bushing.

This is why the WNG hard bushings stability have the potential to be such an improvement over these felt bushings. However,  WNG centers have to often be repinned as well initially, and reaming, which in a WNG bushing is deforming the bushing, takes some serious time as well, and the material can sometimes remember the pre reamed dimension.

All of this says very clearly to me, that one should take care to target the resistance window, but not fool one's self on how accurate or small that window really is...I think its really a surprisingly generous window.

Jim Ialeggio  



 

-------------------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
-------------------------------------------



---

 I was taught that the birds eye determines pin size and to only go up a 1/2 size in pin. Forcing too big a pin can split the wood. Drilling out a birds eye was a no-no..
Perhaps rebushing and reaming with smaller reamers is the answer to get more friction. I like the  center pins from WN&G

-------------------------------------------
James Kelly
Pawleys Island SC
843-325-4357
-------------------------------------------


Original Message:
Sent: 07-30-2014 14:43
From: Jim Ialeggio
Subject: Rep lever pinning

-
<David S- take 2 -What does all this tell you?

What you are observing, as far as inconsistent and backwards results, says to me positioning of the pin in the felt is difficult to repeat with the precision required for really precise results. I have had similar experiences. Earlier on, despite very careful tracking of the results and various procedures, results were inconsistent, resistance generally dropped the next day, sometimes continued dropping a couple of weeks later.

This is why, when possible, I would really like to leave the parts assembled and avoid physically messing  with the interface, unless forced to. It is also why I like the alcohol/water sizing technique, which really seem to be pretty generous in the accommodating imprecision department, is so attractive, both in terms of speed and stability(relative stability that is)

For tightening, Chris Brown has a technique that I have not been able to duplicate results on yet, but I have a call into him on it. He sticks a pin into the felt while the pin is installed to increase resistance. He says its somewhat stable...though the word stable has to be taken with a grain of salt, as the next guy who walks into the room with a cup of coffee will change resistance in any felt bushing.

This is why the WNG hard bushings stability have the potential to be such an improvement over these felt bushings. However,  WNG centers have to often be repinned as well initially, and reaming, which in a WNG bushing is deforming the bushing, takes some serious time as well, and the material can sometimes remember the pre reamed dimension.

All of this says very clearly to me, that one should take care to target the resistance window, but not fool one's self on how accurate or small that window really is...I think its really a surprisingly generous window.

Jim Ialeggio  



 

-------------------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
-------------------------------------------



---