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Baldwin L - Question about the hitch pin design

  • 1.  Baldwin L - Question about the hitch pin design

    Member
    Posted 24 days ago
    I'm curious about the hitch pin design on the Baldwin Model L piano- I'm sure I've seen it on other pianos too, but most recently the Baldwin model L.

    What is this type of hitch pin called and what is its function/purpose?

    Thank you :)

    The touch and tone on this piano is just beautiful, Baldwin made some very fine grand pianos "back in the day"!



    ------------------------------
    Sean Stafford
    Endicott NY
    607-239-4643
    ------------------------------


  • 2.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 24 days ago
    Those are vertical hitchpins. They allow the manufacturer some flexibility in setting up bridge height and achieving a target down bearing. Achieving target bearing is actually quite hard to do with precision, so these allow some downbearing adjustability.  I use these in my rebuilds often. Also, I believe Baldwin was using adjustable plate bolts, to further allow flexibility in hitting down bearing targets in the factory. I use adjustable plate bolts as well, fir the same reason.

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



  • 3.  RE: Baldwin L - Question about the hitch pin design

    Registered Piano Technician
    Posted 24 days ago
    I don't do vertical hitches but adjustable perimeter bolts are a definite plus for reasons mentioned.

    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 4.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 24 days ago
      |   view attached
    This type of hitch pin is known as the Accu-Just. I am uploading a technical bulletin on the subject that was issued by Baldwin which explains it, how to set and make adjustments. I have seen it only on Baldwins . I looked into it when I was working on an L and was concerned what I would have to do if a string decided to pop. The piano in question had several successive notes with a cheating jack issue. After multiple repairs to the same whippens and jacks I attributed it to poor bushing cloth. Apparently the piano was made during the dying years of Baldwin . Rebushing with good high quality bushing cloth made the problem go away

    ------------------------------
    James Kelly
    Owner- Fur Elise Piano Service
    Pawleys Island SC
    843-325-4357
    ------------------------------

    Attachment(s)

    doc
    Baldwin AccuJust.doc   47 KB 1 version


  • 5.  RE: Baldwin L - Question about the hitch pin design

    Posted 24 days ago
    The Accu just system is a great invention for the piano.  The doc james shared is very useful. The valuable lesson i learned from it years ago was you only have one real pass at setting bearing and that preloading a board is counterproductive.  I show the essential tools on a video i made a while back,although i use a different bubble gauge today.

    -chris
    https://www.youtube.com/watch?v=K_ODcyxXsbI

    ------------------------------
    Chernobieff Piano Restorations
    "Where Tone is Key"
    chernobieffpiano.com
    grandpianoman@protonmail.com
    Lenoir City, TN
    865-986-7720
    ------------------------------



  • 6.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 24 days ago
    Jim,

    Thank you for sharing this technical bulletin! The L is one of my personal favourites when it comes to scaling, it really voices up nicely.

    Be well and have a great finish to the week!
    Ian

    Ian Graham
    Piano Technician
    Instrument Restoration
    www.igraham.ca




  • 7.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 24 days ago
    There is an interesting line in the conclusions on the Baldwin PDF...

    1. A bearing value, previously set, cannot be rechecked because the accumulated force of all strings on the bridges will lower the soundboard crown and reduce the settings which were originally set.

    This is interesting. They have set the bearing values in the PDF higher than the bearing values after the board is loaded. This is because, they are expecting fully loaded DB force to be significantly reduced from these angular targets at initial loading. In most of the belly, not really the high treble, but the deflecting part of the belly, the soundboard will deflect downwards, from initial; zero loading, thus reducing the bearing angle and thus the DB force. There is no indication of what the in-service loaded DB angles(or values) will be, or are targeted. One must assume the angles and force they are targeting will be lower the values they are targeting at initial loading, given their statement above.

    To my thinking, and, as per my own targeting,  I proceed differently, as I use this system in my own rebuilds all the time. Since I have adjustability,I don't really care what the load was at initial loading. I care what the long term bearing will be. And I care that that bearing should be minimal. The composite angles they are setting, before board deflection 1.5 high treble to 0.5 in the bass, will in service, be considerably lower than those values. I completely agree with getting the DB values and DB force off the poor board, and this, if I am reading it correctly, agrees with my own loaded, in-service targets...that being, keep the damn DB low, lower than the 1.5-.5 targets we often see espoused.

    In my view, the difficulty presented with setting DB in a system where DB cannot be adjusted much if at all, as in most systems, is that targeting low DB, is quite difficult, unto impossible to do in some parts of the board. This because, for instance, low DB in the high treble means the bridge cap must be planed so it is .020" above a straight string plane. This is almost impossible to hit , without some means of accurately pre-loading the board, pre-stringing, without some means of adjustability. And therefore, the bridge is often, by default, planed higher, installing 2 to 5 deg DB as a safety measure to insure there is not 0 or negative bearing...thus overloading the board

    In my own case, I iteratively adjust my adjustable system. Once after all the strings are on the long bridge,, and then a month later or so, after initial creep and deflection have equalized. My in-service loaded angles are kept low. Unlike Baldwins description, I maintain the actual low loaded target after loading, rather than making assumptions as to where the board ended up on its own after initial deflection equalized.

    I fundamentally disagree with Chris' statement, that preloading is couter-productive. In reading Baldwin's PDF, one must realize that their bias in how they proceed, is defined by the fact that they are a manufacturer, not a small shop rebuilder or site tech. For their process, they want to do this once, not iteratively for financial reasons.

    The bottom line, I take away from this though, is that the in-service angular targets are assumed to be lower than that stated in the PDF.

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



  • 8.  RE: Baldwin L - Question about the hitch pin design

    Posted 23 days ago
    There were a couple of Baldwin bulletins put out. The one that James shared i believe contain some errors. The source of the error is the Baldwin gauge is different than the Lowell gauge, so conversions are necessary and problematic. I believe there was a letter circulating in which Nossaman was making conversions.
    Anyways the error is the assumption that the numbers are degrees, they were percentages of tension The real degrees are (Baldwin R for example) notes 1-26 =.29 degrees downbearing angle, 27-43 =.29 degrees, 44-53=.57 degrees, 54-88 = .89 degrees. My calculations show this is about 400 lbs of total downbearing on the board.  Look for the Technical that is dated 3-27-01, it has diagrams and all the formulas Baldwin used.

    -chris

    ------------------------------
    Chernobieff Piano Restorations
    "Where Tone is Key"
    chernobieffpiano.com
    grandpianoman@protonmail.com
    Lenoir City, TN
    865-986-7720
    ------------------------------



  • 9.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 23 days ago
    400lbs assumes Baldwin's high 180lb tensions. Less than 350-ish lbs, for a scale in the 160lb range and 333-ish in the 150lb range.

    Can't find a reference for that technical on the interpoops.  Chris, do you have one you could share?

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



  • 10.  RE: Baldwin L - Question about the hitch pin design

    Posted 22 days ago
    Only for the price of one of your rib scales.

    -chris

    ------------------------------
    Chernobieff Piano Restorations
    "Where Tone is Key"
    chernobieffpiano.com
    grandpianoman@protonmail.com
    Lenoir City, TN
    865-986-7720
    ------------------------------



  • 11.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 22 days ago
    Chris, my rib scales are ancient history. I completely ditched the stiffness profile I was using, about 5 years ago...too stiff for my musical tastes. Trebles were nice, customers were, and are, still very happy. But to my developing sensibilities, they sounded like they had a poker up their ass.

    Haven't made a board in a while, as I prefer the sounds coming out of the apparently dead vintage boards I have been resuscitating. It is a diagnostic protocol which continues to produce some of my best work. The diagnostic protocol, has no spread sheet component, and is entirely empirical. It is widening out to show how to diagnose and redesign, in-situ, current, high end, compression boards, where the bounce has gone from their bungee...as is common in a compression board. Flat as a pancake.(note the technical spread sheet oriented jargon...bungee, and pancakes are very technical terms, as I'm sure you will agree.)



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



  • 12.  RE: Baldwin L - Question about the hitch pin design

    Registered Piano Technician
    Posted 21 days ago
    Jim,

    You mention that you "prefer the sounds coming out of the apparently dead vintage boards I have been resuscitating."

    This is very interesting to me. I used to build guitars for a custom builder 20 years ago (Spirit Wind Guitars, now Miller Guitars). These are very nice high end hand made guitars. I was taught that over time a solid top would mature in tone. These were flat top guitar like Martin D28s as most acoustic guitars are. So no crown involved with most guitars. The tone demonstrations of aged tops are significant. Rib placement on a guitar Is also significant as are other aspects.

    When I got into pianos I learned crown is important and made the mistake of assuming an old board would sound tonally mature.

    You are resuscitating your old
    boards. So I would like to know what you are shooting for: assuming some crown, down bearing and other things? (But perhaps not). And what tone in an old board you like so much more than a new board? If possible to describe.

    I guess I am looking for a general but not detailed or vague description of what you like and are shooting for. Is it that you just "like" the tone of old boards? What do you find superior in an old board over a new one.

    maybe I am
    misunderstanding your comments in your post.

    Anyway, I am fascinates and would liken to hear more.

    Thanks!
    daniel

    ------------------------------
    Daniel Achten
    Chattanooga TN
    423-760-2458
    ------------------------------



  • 13.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 22 days ago
    It is important to note that on the Baldwin publication that I have it is clearly stated the the tension must be down and that as one progresses through the process of setting downbearing that it is impossible to recheck to the same angle due to increasing load and and board flex.

    ------------------------------
    Michael Evans
    Mansfield TX
    817-822-3591
    ------------------------------



  • 14.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 22 days ago
    This instruction makes absolutely no sense to me. What the devil were they getting at?

    It is possible to check the as-built angle at tension, and adjust at tension, instead of guessing where the board will end up. Why the guessing game?



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



  • 15.  RE: Baldwin L - Question about the hitch pin design

    Posted 22 days ago
      |   view attached
    The rib scale info was only for educational purposes. I find it fascinating regarding the modern ideas as compared to the originals. For example Erwin is very similar to Conover, i suspect from previous conversations you are similar to Knabe. Love is just out there in outer space (just kidding), well kind of.
    Anyways, i thought i lost the document mentioned before, but found it on a hard drive i save to. So i'll attach it.
    I believe Mr. Evans is in error. All the Baldwin technicals i have essentially state, the strings have to be up at tension, but zero downbearing before starting the downbearing process, and then only one pass through the process.
    Enjoy the technical, i think its the best one of all the ones i found.

    -chris

    ------------------------------
    Chernobieff Piano Restorations
    "Where Tone is Key"
    chernobieffpiano.com
    grandpianoman@protonmail.com
    Lenoir City, TN
    865-986-7720
    ------------------------------

    Attachment(s)



  • 16.  RE: Baldwin L - Question about the hitch pin design

    Registered Piano Technician
    Posted 21 days ago

    I think it's the same as the difference between preload bearing and residual bearing. 

    If you set the bridge height to reflect 1.5 degrees of preload bearing, for example, once strung and brought to tension the board deflects some percentage and what's left is the residual bearing. You can't really tell your starting point from the residual bearing because board deflection always has some amount of unpredictability and variability.   

    The Baldwin accu-hitch pins allow you to target the preload bearing very precisely regardless of how accurately you set the bridge height. If you have targeted residual bearing of, say, .75 degrees you can, after the fact, still make adjustments with the accu-hitch pins, though increasing load is easier than decreasing load. 

    Ultimately the proof of the pudding is in the hearing and adjustments to the load can be made on that basis.  

    No system really allows you to 100% predict residual bearing because residual bearing across the scale depends not only on your preload settings but on how each section of the board reacts as that  influences the residual bearing on adjacent sections. But some systems make it easier to achieve or, at least, adjust to your target. Accu-hitch pins and adjustable perimeter bolts are two valuable tools to do just that.  



    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 17.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 21 days ago

    Daniel <When I got into pianos I learned crown is important

    I learned this too. But what does one do, when a trend of really nice sounding flat old boards, re-worked with an appropriate protocol,  different from the standard fare, keeps empirically proving that this information needs to be qualified?

    Yes a flat board, with a beat bridge cap, and challenged glue joints has nothing tonal to offer.  However, old wood doesn't die tonally or structurally, the glue joints die. I'll repeat that... The wood does not die, even if  it has experienced compression crushing. The glue joints die. Old spruce, even though compression crushed, can have a singular mature sound to it, that I really like.

    So what's the deal wth crown? In my experience, crown simply is a visual indicator that the board has enough structure to resist downbearing force. If it can resist downbearing it is a visual indication that the board has adequate structure to produce nice tone. So crown, I would argue, in and of itself, does not produce tone, it is merely a structural indicator.

    If a board is flat, you lose the visual structural evidence that crown offers.  But, lack of crown, does not definitively say there is no structure. It just says there is no visual evidence of structure. There may be sufficient structure, or there may not be. Other diagnostics, other than visual evidence of crown must be employed to know. 

     An apparently dead flat board will either have:

     1-obviously failed glue joints. Or, in the case of hide glue joints, though not obviously failed, joints that are compromised sufficiently, to be incapable of producing sustained tone.  In the case of these compromised hide glue joints, if you were to take  visually acceptable, vintage hide joints apart, often, one could see at least 50% of the joint had turned to powder in the joint. 

    or

    2-In the case of a compression board, where the glue joints are current and probably ok... due to the compression collapse of wood cells, the panel's dimension across the grain is reduced to such a degree, that the width of the panel, relative to the rib length, no longer forces the panel into compression.  Either the rib dimension, or the near rim thinning, or probably both, at this point is too flexible to allow what structure is extant, to function tonally. 

     So, I've mentioned this before. On an old flat board,  I assume compromised joints, and add a small fillet of either G-flex or  1:5 epoxy and colloidal silica along the entire length of all the ribs, both sides. I may add a fillet at the rim if I have concerns about that glue line, as well. I do not use any soundboard washers or any of that traditional protocol, which, from all the evidence I can see, is a complete a waste of time.

     In addition to that, learn how to replace both the long bridge and bass bridge cap. It is the biggest bang-for-the-buck going in piano restoration...absolutely essential to sustained, clean piano tone. In doing the cap, add adjustable plate bolts and maybe vertical hitches. This, to minimize downbearing. The board will now have adequate structure, but its structure will  be overwhelmed by superflous downbearing.

    Finally, only use a cold pressed resilient low density hammer, like a Ronsen Bacon. Use of any hard dense hammer will really challenge success...thank goodness for Ray Negron.

    There is more to it, on a failed compression board that has been treble thinned, but this is enough for now. Also more to it in terms of tuning the impedance of the board with focused, non-centered mass loads, and a protocol to let the board tell you what it wants pre-stringing. I may save that for a class, as its a work in progress.

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



  • 18.  RE: Baldwin L - Question about the hitch pin design

    Posted 19 days ago
    "So what's the deal wth crown? In my experience, crown simply is a visual indicator that the board has enough structure to resist downbearing force. If it can resist downbearing it is a visual indication that the board has adequate structure to produce nice tone. So crown, I would argue, in and of itself, does not produce tone, it is merely a structural indicator."

    The crown produces the right conditions that enhances the tone. And it can be easily demonstrated.
    This morning i did some aural tests with a tuning fork attached to a flexible piece of spruce. Here are my observations:
    Just striking the tuning fork by itself is of course barely audible as everyone knows.
    I attach the tuning fork to the spruce and it is more audible, but the tone's emphasis is more on the partials.
    Then i apply tension to the spruce and there was a noticeable improvement of the volume and the fundamental.
    There seemed to be a sweet spot when the fundamental was the most prominent. And this was when there was just barely enough tension applied. Visually i would say it was about a 60' radius or less. I was surprised by that.
    When i crowned too far the fundamental went away again, with a slight decrease in volume also.
    When i put one end in the vice and with no tension in the spruce. The tone became "woody" and also took on the character of the vice.
    When i  again applied a little tension, to the sweet spot, the fundamental again return as prominent, and i could not hear the vice.

    -chris



    ------------------------------
    Chernobieff Piano Restorations
    "Where Tone is Key"
    chernobieffpiano.com
    grandpianoman@protonmail.com
    Lenoir City, TN
    865-986-7720
    ------------------------------



  • 19.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 19 days ago
    Then there is the empirical evidence, following a trend of successful uncrowned boards, which does not support your interpretation of what you did in your test. These flat boards perform quite well all over the scale, including the treble...given really good terminations at the bridge pin, and pivot terminations at the capo termination.

    All you did was to impose a higher level of stiffness onto the system. Stiffness is required, as a crossgrain piece of spruce has next to no stiffness.  Stiffness can be imposed by multiple vectors, say like ribs, for instance

    Instead, install, in a manner consistent with the scale of your test piece, one or two small flat ribs, similar to a guitar. Then repeat your test. Assuming the ribs are appropriate dimensions, what do you find? If it doesn't work the first time, adjust your rib dimensions until it does work.

    (edit vestigal paragraph)

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



  • 20.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 19 days ago
    Said another way,  your test would only have meaning if you could impose crown without changing the stiffness profile of the spruce sample. Your test changed two parameters, crown and stiffness. You chose to attribute the change to the crown. THis, under these test conditions, is a biased interpretation of the results.

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



  • 21.  RE: Baldwin L - Question about the hitch pin design

    Registered Piano Technician
    Posted 18 days ago

    I think crown serves two main purposes:

    One, because you have a dome shaped, non linear spring that stiffens as it is compressed you can build the assembly lighter and still achieve the requisite stiffness with downbearing. 

    Two, downbearing loads the assembly with potential energy  You have one spring (strings) pushing down and the other (the assembly) pushing back against it. That creates a more dynamic structure than one without those two factors at play  

    I don't think guitars are a good comparison whether flat top or arched top. The load on a guitar top is pretty marginal. A set of light gauge strings on a guitar has about 110lbs of total tension compared with 32,000 - 40,000 lbs in a piano. The downbearing load on a guitar is nominal, In fact the force is pulling up on the back of the bridge and down on the front of the bridge. The dynamics are totally different. 

    Jim, I'm curious when you reuse an old panel how do you tend to modify the rib scales, or do you?  Do you remove them and dry the panel in order to reestablish some compression crown reusing the original ribs?  Or do you make a new rib scale?  Are they crowned?  How do they compare dimensionally?  

    I don't see a problem reusing an old panel necessarily, depending on the health of the panel or how you repair it. Old wood probably does produce something different than new wood just like different species produce somewhat different results. But  there are so many variables when trying to compare them it would be difficult to tease out whet was affecting what. 

    The other thing is that if the board starts out flat and you set positive bearing so that you are pushing the board into a concave shape you still have a dynamic situation. Of course we consider that a no no based on tradition but is it really a problem?  I'm not sure. 



    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 22.  RE: Baldwin L - Question about the hitch pin design

    Posted 18 days ago
    Yes, its a problem because in a concave situation, you are putting tension across the grain. Wood don't like that.
    -chris

    ------------------------------
    Chernobieff Piano Restorations
    "Where Tone is Key"
    chernobieffpiano.com
    grandpianoman@protonmail.com
    Lenoir City, TN
    865-986-7720
    ------------------------------



  • 23.  RE: Baldwin L - Question about the hitch pin design

    Registered Piano Technician
    Posted 18 days ago
    I meant is it necessarily a tonal problem i.e can a panel still produce decent tone in that situation. I'm not advising it.

    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 24.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 18 days ago
    Any crown contains both tension and compression. One side will be compressed and the other in tension. There is no physical difference between the two directions...they both have crown, and both have one side in tension, and one side in compression. I'm not advocating an oil-canned crown, but physically there is no difference in the wood deformation, I don't think.

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



  • 25.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 18 days ago

    What I am saying is that crown and no intentional crown, both function. However, they are different physical systems, so they have to be treated differently.

    Compression crowning does impart a low mass stiffness. I'm not disputing that at all.

    In setting up a compression crowned board, the builder will load it heavier than non-crowned board, committing to a bridge height which is appropriate for that level of crown and stiffness. They will also thin parts of the panel, particularly the treble which depend on the panel's original cross-grain dimension to function. The problem with this setup is, that when the compression goes south, that thinned portion of the panel, which was a benefit when compression was extant, becomes a serious problem. Senza the compression, the near-rim area at the tight bend of the case, becomes way too flexible, and the treble anchor to the rim provides an insufficient foundation for the panel to work off of.

    There may be more power in a compression board with extant compression, than in non-compression systems, but, frankly, except for concerto pianos, non compression pianos still pack a huge amount of power...more than most spaces can contain.  The question is how much power is necessary for 99% of pianos out there.

    In a non-compression system, which I will assume all the boards I am working with are, when I'm using this protocol, they don't have the annoying race horse sound of a compression board...there is a relaxation to the sound which I find entrancing...frankly a sound I have been looking for my whole life in piano land.

    My system for reusing the board is rot-gut simple.  I don't remove the board, or painstakingly disassemble it like Craig Hair and Richard Blais do. Although their work inspired what I am doing..I really respect what they have been doing.

    I will only work on boards who are not falling apart. Some, to a bunch of cracks are ok, as long as the separations at the ribs are not out to lunch. Strip the board in-situ...it stays in the piano. At the separations only, open the separated joint to new wood. This joint will get G-flex in the actual joint. The rest of the rib scale, or as much as I can get to, gets a small 3/16 to 1/4" fillet of G-flex along the entire length of each rib. That's the entire length of each rib, not just at separations.

    My assumption is that all the rib joints are compromised, and I proceed from that assumption.  If the rim joint looks like it may have compromised joints, I probably will just do a new board. If they rim joints look reasonable, I may add a fillet at that joint as well.  So, that's the bottom side.

    Top-side, I use a luthier's non-invasive thickness probe,  Maj-ic Probe , to map where the board had been thinned, and see what the manufacturer was up to. If there is thinning at the treble bend, I will add veneer back to the panel, that the manufacturer took off, to some degree. Then I use a violin plane to taper it into the existing board.  Other parts of the board, can be ok when compression goes south, but I run diagnostics to see if I need to correct those thinned areas or not. This, by mainly using a type of tap test on the bridge to see is the board, when driven,  sustains , and if it sustains if it tends to break up. You can hear this tapping on the bridge itself. I mainly tap on the bridge, not the panel for this, and use a small ball peen hammer hitting a double thickness of backrail felt.

    Rib dimensions mostly stay original. I have reduced some very high bass ribs on some Chinese experimental offerings, and have added to rib 8 on my current project. It is interesting to see how starting with more added stock than I knew I would end up with, how the tap test at that rib location changes with as I remove millimeter  by millimeter...very interesting. Ended up only adding 2mm on this one.

    The rest is termination work, which is absolutely essential. Always a new cap and pins...never re-using the old cap.  This protocol has gone hand in hand with a tighter front and back pin spacing (10mm) where I can get it. ..especially the high treble and all of the tenor and bass, pivot terminations at the capos and copolymer counterbearings. ..Ed Mcmorrow's FTDS almost always.

    Adjustable plate bolts and often at least some vertical hitches are essential as well, to keep the load on the board minimized.  Final DB angles after loading and a month or two of equalization, is .7-ish high treble, to as close to not bearing as I can get it in the bass. Vertical hitches  help with this.  Board is loaded when setting bridge height with my calibrated spring loaded go bars, so I can see what the board can support.  Flat boards treated with this protocol, can actually take some load without oil-canning. Which means flat does not necessarily mean no structure. But one must pay attention to the load, as it is key, and load the thing to see what it can take, after the re-gluing process is complete.



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



  • 26.  RE: Baldwin L - Question about the hitch pin design

    Member
    Posted 18 days ago
    FYI, I only started experimenting with this on a horrible no-name runt piano I did a couple of years ago. There was limited budget, to do too much, an I used this as my first victim. The piano came out sounding, frankly, surprisingly good...pretty damn nice, considering what a POS it was. So, I observed that result, sat up and listened. I have been further developing the protocol since then, with excellent results on all the pianos. So, I'm looking at a trend, rather than a single data point.

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



  • 27.  RE: Baldwin L - Question about the hitch pin design

    Registered Piano Technician
    Posted 17 days ago

    Intuitively it seems there is a difference in the panel itself but I'm not sure, I'll have to let the engineers weigh in.


    But the dynamics of the assembly would certainly be different. In one case the assembly is solely responsible for crown formation and the string scale applies a counterforce which compresses that crown. In the oilcan situation the downbearing force applied by the string scale is solely responsible for the "crown" formation and there is no counterforce. That seems likely a pretty important distinction. 



    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
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  • 28.  RE: Baldwin L - Question about the hitch pin design

    Posted 16 days ago
    Jim said  "Any crown contains both tension and compression."

    This needs further clarification. A hygroscopic panel with low moisture content and used the way it is as a soundboard, would be under compression. Maybe higher compression at the bottom of the thickness than at the top, but all of it compression until something goes wrong over time.
    The whole soundboard structure may be different,  panel - compression, ribs - top half tension, then a central axis, and bottom half compression.

    -chris


    ------------------------------
    Chernobieff Piano Restorations
    "Where Tone is Key"
    chernobieffpiano.com
    grandpianoman@protonmail.com
    Lenoir City, TN
    865-986-7720
    ------------------------------



  • 29.  RE: Baldwin L - Question about the hitch pin design

    Registered Piano Technician
    Posted 14 days ago

    The only addition to Jim's comments is that I now prefer solid pins as opposed to the hollow spring pin used by Baldwin. Different companies make different styles. Groov-Pin is one. Driv-Lok is another. (See the links below). 

    https://groov-pin.com/product/type-2a-grooved-pins/

    Type 2A Grooved Pins - Groov-Pin Corp.



    ------------------------------
    [Delwin D] Fandrich] [RPT]
    [Piano Design & Manufacturing Consultant]
    [Fandrich Piano Co., Inc.]
    [Olympia] [WA]
    [360-515-0119]
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  • 30.  RE: Baldwin L - Question about the hitch pin design

    0