Pianotech

  • 1.  Nosebolts

    Registered Piano Technician
    Posted 02-08-2023 10:35
    While I am well aware of the standard advice to make nosebolts "neutral" (i.e. just kissing the plate and not exerting any upwards or downwards influence), I have cone across several instances where one particular nosebolt (the one that intersects the crisscross at struts #1 and #2 on many pianos 6' and up [near the lower tenor]) has been deliberately adjusted from the factory with significant upward pressure at this point.  IOW the casting is clearly being pressured (tensioned) upward with a resulting downward force to the beam(s) underneath where it is attached.

    Has anyone else observed this phenomenon? I've seen it primarily in Steinway B's and now in a Kawai GS-60.  This is not plate warpage nor an accident since all other nosebolts have been carefully adjusted to neutral.

    Is there some design advantage to this? Is it doing something dynamically to the structure that enhances the sound? ​I have historically returned it to a neutral position in the rebuilding process, however I clearly recall one B about 25 years ago where the piano "seemed" to be somewhat less vibrant afterwards than before (this may have been the first time I noticed this and it was SIGNIFICANT).

    Yes, i am aware that nosebolts do get adjusted for various "undocumented" purposes. ​ Open to ideas on this.  Specifically wondering if I should re-institute the situation on this Kawai as I found it, or should "neutralize" it.

    Peter Grey Piano Doctor

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    Peter Grey
    Stratham NH
    (603) 686-2395
    pianodoctor57@gmail.com
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  • 2.  RE: Nosebolts

    Registered Piano Technician
    Posted 02-08-2023 11:05
    Yes, Peter.  It is something I watch for when I am removing the plate bolts.  I deliberately remove the lowest bolt in the tenor last to see if the plate will rise as I unscrew the bolt.  Not uncommon on Steinways, I have seen a plate rise 3/4" or more.  My guess is that they are checking the bridge height and finding it too high.  But the acoustic dowels are already set at their height for the bolts and the bridge top already drilled and pinned, so they are painted into a corner unless they do something like turn up the nosebolt until they are happy.  I have seen this often enough over the years with Steinway grands that I would almost call it commonplace.  

    If you have taken bearing readings before restringing, that will help you with the right answer.  

    Mostly I set them to nuetral when the plate goes back in.  

    This makes a good argument for adjustable plate bolts ala WNG.  If you make a mistake, you don't always have to live with it.  

    It makes you realize that you do not have to baby the plate as much as you thought.  It is pretty forgiving of our sins

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


  • 3.  RE: Nosebolts

    Registered Piano Technician
    Posted 02-08-2023 11:43
    Will,

    Yes, similar here. Although this particular nosebolt I cannot see having any effect on downbearing due to its location and design. The other ones definitely though. (I have bent the "rules" on those before).

    Peter Grey Piano Doctor

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


  • 4.  RE: Nosebolts

    Registered Piano Technician
    Posted 02-09-2023 06:13

    I recall Chris Robinson theorizing that this was the result of load deformation of the rims over time, and that he had confirmed this with straightedges and/or levels. I would have thought the tail of the rim would rise over time instead of dropping, but like you found it to be very common if not ubiquitous, at least on Steinways.



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    Mark Dierauf RPT
    Concord NH
    (603) 225-4652
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    Original Message


  • 5.  RE: Nosebolts

    Registered Piano Technician
    Posted 02-09-2023 08:49

    Well, so here is what I have decided to do. After setting the nosebolt to just kiss the bottom of the plate at the X, just for fun I grasped the struts on each side of it and forcefully jerked upward (to see if there was any flex to be had here). And what dobyiu think I found? I heard a clear "knocking" sound coming from the nosebolt. I thought: "Hmmm that's interesting". I turned the nosebolt up a tad and repeated the procedure. As I did, the knocking got less and less until I reached a point where it disappeared. I then made it permanent at that point. So basically a compromise between absolute neutral and stressed. I will perform the same analysis on every piano from here on out. 

    Peter Grey Piano Doctor 



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


  • 6.  RE: Nosebolts

    Registered Piano Technician
    Posted 02-09-2023 09:21
    I was in one of Del Fandrich’s classes in my early years of restringing pianos. I mentioned that I had used the nosebolts to adjust down bearing. Del said, “Naughty, naughty.”

    Bob Anderson, RPT
    Tucson, AZ


    Original Message


  • 7.  RE: Nosebolts

    Registered Piano Technician
    Posted 02-09-2023 10:11
    I have used nose-bolts for bearing adjustments, particularly on old boards that can stand a slight lessening of bearing on the very ends of the bridges (A0 and C88) in order to get some bearing at all across the middle.  I have measured with a dial caliper before and after destringing to see what sort of beginning flex I have in the plate.  I have usually found the bolts  holding the plate up, but on occasion, I measured over .200" plate rise when I loosened the cap screws on the bolts. I would not want to bend one  more than that, so I lowered all the 'acoustic dowels' around the rim by .100"  and dropped the nose bolts by same amount.  

       Bill Garlick mentioned one of the Glazebrook brothers at the London Steinway dealership  saying that he lowered nose-bolts quite often to improve bearing.  I cannot afford to replace the pianos I work on, so I am more conservative than that.  I have broken the plate of an older upright before it was scrapped.  I used the nose bolt through the long bass strut and it was nearly 1/2" before it broke. 
    Regards, 



    Original Message


  • 8.  RE: Nosebolts

    Registered Piano Technician
    Posted 02-09-2023 12:26

    A couple of years ago I installed a set of WNG plate bolts in a 1916 Steinway O that should have had a new board but the customer nixed it.  I also capped the bridges and set the bearing.  This was a flat old board that I wanted to conservatively milk what I could get out of it without going too far, and I maintained a healthy sense of paranoia.  I could be very precise in laying out any tilt that I might want to introduce bass to treble.  My idea was to baby it up to as much bearing as I felt I should, but keep an escape mechanism if I needed to back off.  The WNG bolts and the adjustable nose bolts gave me that option.  This included making adjustments after the piano was strung and up to pitch, with a fully functional action and a reasonable amount of voicing.  This I did by loosening the bolt that goes through the plate and setting it aside, doing this on every other bolt.  Using an allen wrench, I then turned the bolt down a certain amount.  I reinstalled the bolt and repeated the process on the other plate bolts.  I have done this several times on a piano and it is safe.  Puts the piano WAY out of tune, though.   



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