Pianotech

Expand all | Collapse all

Restringing Baldwin acu-just with interesting issue

  • 1.  Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-28-2024 21:49

    Hello,

    I'm restringing my first Baldwin (model L) with accu-just hitch pins. I spent some time with factory documents and I think I have my head wrapped around the system. To set downbearing, I have a digital level/angle gauge placed on top of a downbearing rocker gauge, zeroed out when tilted on the speaking length.  I then rock towards the hitch pin for exact angle. I'm puzzled: when restringing, I placed the strings towards the top of the hitch pin and was still getting positive bearing. Moving the string up any more is not possible, and the portion that needs to be set with 0.5 degrees (notes 23-40 off the top of my head) is reading around 1 degree. I took photos prior to removing the strings, and the strings were significantly farther down the hitch pin in the original configuration.

    I believe the piano did spend years in a much drier climate before being moved to South Central PA. It has had a Dampp Chaser for many years at this point as well. 

    Questions:

    1. Is it possible downbearing was set for a drier climate?
    2.  How close to the top of the hitch pins can I safely set the string?
    3. Additional advice in this situation?
    4.  Am I missing something

     Thank you!

     Edit: just realized it’s two Cs in accu-just. 🤪



    ------------------------------
    Tim Foster RPT
    New Oxford PA
    (470) 231-6074
    ------------------------------



  • 2.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-28-2024 22:12
    Did you remove the plate?  If so, are you sure it's back down where it was before? 

    For setting the string on the hitch pin, the advice I got from Baldwin is to make a jig out of a small piece of wood, (3" long and about 3/4" wide), with a notch on one end that lies on the plate and fits on the hitch pin. Before removing the strings, measure the height of the strings on the hitch pin, and then make the notch end of the piece of weed the same thickness as that measurement.. According to Baldwin, the distance should be the same on all the pins. You might need to make minor adjustments on each pin to get proper rear down bearing. 

    Wim





  • 3.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-28-2024 22:27

    Thanks, Wim. I did not remove the plate, I should have included that info in the OP.



    ------------------------------
    Tim Foster RPT
    New Oxford PA
    (470) 231-6074
    ------------------------------



  • 4.  RE: Restringing Baldwin acu-just with interesting issue

    Member
    Posted 10-29-2024 01:30

    Wim .... make the notch end of the piece of weed   I think you meant wood.... Baldwin had some type of tool to do the height at the hitch pin but I think a wood guide to set the height will work just fine My understanding of this system is that it helps with the crown of the soundboard and is a factory setting. I think the height should be further down the pin. There is the same piano at a dealer near here so maybe I can get one of my tech friends to measure. I also have a customer with an accu just hitch pin system that I think is the same model



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



  • 5.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-29-2024 07:28
    Wim .... make the notch end of the piece of weed   I think you meant wood...

    I probably had weed on my mind. Next week Firodia is voting on a constitutional amendment to allow recreational marijuana use. lol





  • 6.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-29-2024 03:26
    Marketing hype aside, this system was developed to aid manufacturing. It allowed the company to fully process the bridges 'on the bench' before they were glued to the soundboard and installed in the piano. It also allowed the workers to "properly" set string bearing regardless the ambient relative humidity (hence variabilities in soundboard crown). The floating string frame mounting was intended to get the string frame relatively close to 'ideal' and then the strings could be adjusted up or down on the pins to fine adjust for string bearing no matter what. 

    Others have given suggestions for setting the string height on the pins. I'll just add (in response to your question #2) that it was my preference that the strings should never, ever, be more than 10 mm above the surface of the string frame. Five mm (or even less) is better. Yes, I've seen them higher. But, remember, the higher the string on the hitch, the greater the stress on the string frame. If you can't get down to this, raise the height of the string frame. It's not all that hard to do but I can't imagine why it should be necessary in an older piano. 

    Think in terms of an ordinary string frame. There is a bearing bar back there someplace. How would you go about setting string bearing on that? This is not all that different except that you have some adjustability. 

    Don't bother trying to set each string pair to some individual height. Establish a reasonable string angle at the first and last string of each section (and, perhaps, one in the middle of the section) and level them all to that height. It's not all that different from a "normal" configuration. You don't see those wandering all over the place, neither should these. 

    ddf

    --
    Delwin D Fandrich
    Fandrich Piano Company
    Piano Design and Manufacturing Consulting Services -- Worldwide
    6939 Foothill Ct SW -- Olympia, WA 98512 -- USA
    Phone 360.515.0119 -- Mobile 360.388.6525





  • 7.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-29-2024 12:18

    Tim,

    You can also use the below method taught to my by the late David Betts of NBSS. You can use this as a reference depending of the crown on the soundboard. You can use drill bits for gauges.

    http://goptools.com/dbearing.htm



    ------------------------------
    Tremaine Parsons RPT
    Georgetown CA
    (530) 333-9299
    ------------------------------



  • 8.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-29-2024 14:01

    Tremaine,

    Reading from David Betts diagram (http://goptools.com/dbearing.htm I'm unsure if his calculation is correct regarding proper downbearing. Help me here. It appears he is simply calculating from some arbitrary point on the top of the bridge to that of the aliquot to acquire an appropriate downbearing angle. If my understanding is correct, then his angle calculations are incorrect. Proper downbearing angle is not derived from some arbitrary point at the top of the bridge but calculated from the surface plane line of the bridge to that of the aliquot.



    ------------------------------
    Roger Gable RPT
    Gable Piano
    Everett WA
    (425) 252-5000
    ------------------------------



  • 9.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-29-2024 14:32

    Roger,

    You have raised an excellent point. David explained this method around 1990 and he may have refined it. The diagram indicates measuring from the speaking length bridge pin. I should have mentioned that I believe the method was intended to be a guide and did not intend to give absolute correct numbers. Unfortunately we can no longer consult with David on this. I should update the web page to include this point. I've always been mostly a messenger so you have given me a "heads up" with good food for thought.



    ------------------------------
    Tremaine Parsons RPT
    Georgetown CA
    (530) 333-9299
    ------------------------------



  • 10.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-29-2024 14:40

    I meant to also include that I have most often seen rebuilders use the bubble gauge method to set accu-just hitch pins. I can't recall off hand who initially sold the downbearing bubble gauge and if they are still available. Can anyone update on availability? 

    I personally believe that this would be the best method.



    ------------------------------
    Tremaine Parsons RPT
    Georgetown CA
    (530) 333-9299
    ------------------------------



  • 11.  RE: Restringing Baldwin acu-just with interesting issue

    Posted 10-29-2024 15:02

    So topics such as this is the main reason i created my youtube channel. I have over 400 videos on piano rebuilding and i specialized in many of the "weeds" of piano construction and design to make it unique. I have a few vids on setting downbearing with the accu-just sysem. I also have a vid on how to make your own bubble gauge as an example.

    Don't feel bad, i encourage Techs to go there and learn what you can from it and use it or not.

    And don't forget to like and subscribe and recommend what you would like to see in the future. I have many rebuilds in front of me, so i most likely can fill a request.

    All the Best,

    -chris



    ------------------------------
    Chernobieff Piano Restorations

    Inventor of Inertia Touch Wave (ITW)
    Advanced Resonant Compression Engineered Soundboards (ARCHES)

    865-986-7720 (text only please)
    ------------------------------



  • 12.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-30-2024 12:53

    Chris,

    I viewed your YouTube video on adjusting Baldwin Acu-just downbearing. That process is incorrect. You are using the speaking length of the string as a reference point. The reference point needs to be the bridge cap plane. 

    Roger



    ------------------------------
    Roger Gable RPT
    Gable Piano
    Everett WA
    (425) 252-5000
    ------------------------------



  • 13.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-30-2024 17:22

    I don't know Roger but you may get some push back on this. Looking at the Lowell Bubble Gauge instructions I appears that using the speaking length is described as measuring the "net" downbearing. Instructions here.

    I have not yet watched the video by Chris



    ------------------------------
    Tremaine Parsons RPT
    Georgetown CA
    (530) 333-9299
    ------------------------------



  • 14.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-30-2024 18:21

    Tremaine,

    You are correct about "net" downbearing. You may have good net downbearing, say 3 degrees from speaking to duplex segments, but you could still have a reverse downbearing on the speaking or duplex legs relative to the bridge cap. Reverse downbearing on either side of the bridge cap (particularly the speaking segment) is a common source of false beats.

    Roger



    ------------------------------
    Roger Gable RPT
    Gable Piano
    Everett WA
    (425) 252-5000
    ------------------------------



  • 15.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-29-2024 15:04

    Tremaine,

    The original bubble gauge was made by Tom Lowell sold through Pianotec. Over the years I purchased two from them. When Schaff took over Pianotec I purchased another one for my false beat research. I was disappointed. The construction was compromised. The glass bubble tube fell out, the bearing pin bound up prohibiting any meaningful reading and the calibration angle was so far off that the adjustment screw always needed to be set at the extreme end for most pianos. 



    ------------------------------
    Roger Gable RPT
    Gable Piano
    Everett WA
    (425) 252-5000
    ------------------------------



  • 16.  RE: Restringing Baldwin acu-just with interesting issue

    Posted 10-30-2024 19:27

    Hi Roger,

    Lets just say for a moment you are correct on point, but I believe that would be more the exception and not the rule. On old boards you have to make compromises and use common sense to make things work with  "damaged" goods. I for the most part work on new soundboards with a 50' radius and set the the bride height and bearings within my preferred tolerances. My videos are not educational videos per se, but are more "in the moment" videos that can be learned from. So, every possible scenario is not implied.

    All the best.

    -chris



    ------------------------------
    Chernobieff Piano Restorations

    Inventor of Inertia Touch Wave (ITW)
    Advanced Resonant Compression Engineered Soundboards (ARCHES)

    865-986-7720 (text only please)
    ------------------------------



  • 17.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-30-2024 22:34

    I have a Fowler dial gauge with two feet that extend past the bridge pins and rest on the strings there, with the dial pin resting on the string centered between the pins.  I use that to take a net or combined bearing reading of front and rear bearing.  I will also sometimes take a reading of the front bearing with the dial pin resting just behind the front pin, likewise the same for the rear pin.  And I have seem many pianos where there is positive net bearing and negative rear bearing, sometimes a significant amount.  I record the readings in .ooo of an inch.  It is very fast and easy to use, and it does not tell me any lies.  I have used it for 40 years, and used in many times on Baldwin grands when I was a piano dealer. . 



    ------------------------------
    William Truitt RPT
    Bridgewater NH
    (603) 744-2277
    ------------------------------



  • 18.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 10-31-2024 11:48

    Chris,

    I've always reasoned that Baldwins acu-just system was an excellent method to adjust downbearing, especially on aging boards. Unfortunately, it only addresses the duplex side of the bridge. There are caveats when you only address the duplex side. There could be excessive downbearing on the speaking side, creating too much net downbearing or there could be excessive negative downbearing. If so, the net downbearing could possibly pull the bridge/soundboard up - although that would be a rarity. I have found these imbalanced conditions are not an exception as you state. They are a condition that exists almost 100% in both new and old pianos.

     It's unfortunate my false beat treatise took so long to complete and submit for Journal publication, as this issue is addressed in great detail. Scott Cole informs me it won't be published until possibly January and I'm unwilling to address this subject in a condensed form for this forum.

     P.S. Chris, may I suggest you place a disclaimer on the YouTube video stating your acu-just demonstration is not for educational purposes.



    ------------------------------
    Roger Gable RPT
    Gable Piano
    Everett WA
    (425) 252-5000
    ------------------------------



  • 19.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 11-02-2024 22:24

    Thank you all for your help, everything went together just fine, the piano sounds great and the client was ecstatic!



    ------------------------------
    Tim Foster RPT
    New Oxford PA
    (470) 231-6074
    ------------------------------



  • 20.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 11-04-2024 04:49

    Roger, I believe that you are a rebuilder, yes?  If so, you can have it both ways by using WNG plate bolts or making your own.version thereof.  You can set plate height globally with the adjustable plate bolts, and dial it in for each string with the vertical hitch pin modification.  It can be adjusted after stringing also.  



    ------------------------------
    William Truitt RPT
    Bridgewater NH
    (603) 744-2277
    ------------------------------



  • 21.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 11-14-2024 12:07

    Veering off subject, but I have to ask the following:

    If you raise or lower the plate with WNG bolts after stringing, with the plate firmly screwed to the pinblock, you are flexing the plate. Is this a problem?



    ------------------------------
    John Pope
    University of Kentucky School of Music
    Lexington, KY
    ------------------------------



  • 22.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 11-14-2024 12:41
    While sometimes it's unavoidable, you should try not to put a flex on the plate. But I've taken enough pianos apart to know that it's not always possible, even those which have never been rebuilt. 

    Wim





  • 23.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 11-14-2024 21:20

    Not in my experience.  If you are lowering or raising the plate, the nose bolts need to be reset also.  There may still be some flexing of the plate near the pinblock area, but I believe that would be small



    ------------------------------
    William Truitt RPT
    Bridgewater NH
    (603) 744-2277
    ------------------------------



  • 24.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 11-15-2024 18:40

    I have dismantled several grands that turned out to have seriously contorted plates straight out of the factory. Flexed so badly that, had I done it, I would have anticipated breaking the plate. But no damage. There's more wiggle room there than we were led to believe. I will of course correct what I can, but I can't always eliminate all of it. 

    Peter Grey Piano Doctor 



    ------------------------------
    Peter Grey
    Stratham NH
    (603) 686-2395
    pianodoctor57@gmail.com
    ------------------------------



  • 25.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 11-16-2024 00:27
    Baldwin pinblocks were not glued to the rim structure. It is quite possible to shim blocks as necessary. 

    The string frame mounting system is not the same 
    Plate Suspension Bolt -- HiRes.JPG

    --
    Delwin D Fandrich
    Fandrich Piano Company
    Piano Design and Manufacturing Consulting Services -- Worldwide
    6939 Foothill Ct SW -- Olympia, WA 98512 -- USA
    Phone 360.515.0119 -- Mobile 360.388.6525





  • 26.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 11-16-2024 00:30
    To finish -- 

    Baldwin string frames did not use 'adjustable' mounting bolts as is now common in Chinese (and, probably, Japanese and Indonesian) pianos. We call it the WN&G mounting system because WN&G imports them and sells them here. It's a bit more difficult with Baldwin string frames. 

    ddf 

    On Fri, Nov 15, 2024 at 9:25 PM Delwin D Fandrich <ddfandrich@gmail.com> wrote:
    Baldwin pinblocks were not glued to the rim structure. It is quite possible to shim blocks as necessary. 

    The string frame mounting system is not the same 
    Plate Suspension Bolt -- HiRes.JPG

    --
    Delwin D Fandrich
    Fandrich Piano Company
    Piano Design and Manufacturing Consulting Services -- Worldwide
    6939 Foothill Ct SW -- Olympia, WA 98512 -- USA
    Phone 360.515.0119 -- Mobile 360.388.6525


    --
    Delwin D Fandrich
    Fandrich Piano Company
    Piano Design and Manufacturing Consulting Services -- Worldwide
    6939 Foothill Ct SW -- Olympia, WA 98512 -- USA
    Phone 360.515.0119 -- Mobile 360.388.6525





  • 27.  RE: Restringing Baldwin acu-just with interesting issue

    Posted 11-15-2024 19:24

    Flexing the plate as much as you want is okay, until something breaks, then its not okay. Then you have a big new problem. At my company we don't flex the plates at all because we take the extra effort to make sure the bridge cap and string rest interface is correctly set before stringing. But also the beauty of the accu-just system is that their is some wiggle room for correcting small errors.

    -chris



    ------------------------------
    Chernobieff Piano Restorations

    Inventor of Inertia Touch Wave (ITW)
    Advanced Resonant Compression Engineered Soundboards (ARCHES)

    865-986-7720 (text only please)
    ------------------------------



  • 28.  RE: Restringing Baldwin acu-just with interesting issue

    Registered Piano Technician
    Posted 11-15-2024 20:10

    Peter, having rebuilt a great many Steinway grands over the years, it is not at all uncommon to see the plate rise an inch or so when removing the plate bolts at the bass far corner.  As you turn the last bolt out, you see the plate rise and rise.  That is because they turned the nose bolts up because they had too much downbearing. When installing a plate when rebuilding, I screw down all the screws in the pinblock, set the plate height globally with WNG adjustable plate bolts.  I have set the nose bolts way low, so I turn them up until they just graze the bottom of the plate.  That process can be reversed if need be.



    ------------------------------
    William Truitt RPT
    Bridgewater NH
    (603) 744-2277
    ------------------------------