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Unstable Grand

  • 1.  Unstable Grand

    Posted 07-06-2018 11:55

    Hi Folks.

    I look after a Karl Muller G-175 (perhaps a Samick?) that is terrifically unstable in the mid section, though the bass and treble are pretty good. A well-maintained Piano Life Saver isn't helping much. This piano belongs to a teacher and I have to tune it every 8-10 weeks. All plate bolts are tight and there's no sign of plate damage or problems with the case.

    The one thing I hadn't thought of was the plate flange to pinblock fitting. In the bass and high treble I can 't force a business card in between the block and flange, but in the centre sect ion the gap is .104"!

    I seem to recall someone mentioning that maple shims can be forced into the gap and glued in to help solve that problem. Would that work? Where would I get the shims if it might as I'm not really a woodworker ? How many would I use ?

    Another alternative someone suggested was to turn the piano upside down and fill the gap with epoxy. I n this case that isn't an option.

    Does anyone have any suggestions?

    Thanks

            John



  • 2.  RE: Unstable Grand

    Posted 07-06-2018 12:22
    Interesting question. I've done shimming along the flange area where there was no change in behavior. If there are pin bushings, most of the tension is on the bushing rather than the flange. You could try shimming, just to see. You might use popsicle sticks or force some epoxy putty up in there, or sandwich several layers of veneer. The question is, how stable is the environment? Low tenor area is always moving around with humidity and temperature changes. Put a string cover to buffer the atmosphere. Stage lights? Big room or church sanctuary? Is the piano in good tune when you leave? Or is it so untunable that you can't leave it in tune? I've had trouble tuning a certain brand/brands that came out of Dung Bay that thwarted my best efforts to tune them. Front segments that went steeply down to agraffes that were sticky, coupled with very tight pins. I have one of these that I"ve been tuning for more than 10 years, and it still requires my best techniques and full concentration on.
    Paul McCloud
    San Diego



    Hi Folks.

    I look after a Karl Muller G-175 (perhaps a Samick?) that is terrifically unstable in the mid section, though the bass and treble are pretty good. A well-maintained Piano Life Saver isn't helping much. This piano belongs to a teacher and I have to tune it every 8-10 weeks. All plate bolts are tight and there's no sign of plate damage or problems with the case.

    The one thing I hadn't thought of was the plate flange to pinblock fitting. In the bass and high treble I can 't force a business card in between the block and flange, but in the centre sect ion the gap is .104"!

    I seem to recall someone mentioning that maple shims can be forced into the gap and glued in to help solve that problem. Would that work? Where would I get the shims if it might as I'm not really a woodworker ? How many would I use ?

    Another alternative someone suggested was to turn the piano upside down and fill the gap with epoxy. I n this case that isn't an option.

    Does anyone have any suggestions?

    Thanks

    John


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  • 3.  RE: Unstable Grand

    Posted 07-07-2018 20:05
    Thanks for the suggestions. Some comments:

    I've tightened the plate bolts and screws, squeezed the beckets and tapped the coils, so we can rule that out. The room conditions are fairly stable and the PLS installation was good. I've discussed an undercover with the owner and we may try that as well.

    As for things like the string angles, friction, agraffes and other suggestions, they don't seem to be an issue on this piano. The pins feel good and the few times I've tuned it 30 days apart it seems just fine. it's when it's 60-90 days that it gives me grief. The bass strings are terrible and most of the bichords have pitchlocks on them to try to tame them.

    I'm going to try finding or cutting maple shims and going that route for now. I'm just putting new Ronsen Weickert hammers on it now and will do that when I return the action next week. I'll report on it in the fall. For now, the teacher who owns it is happy enough for me to tune it every 8-10 weeks. It just bugs me because my tunings are always quite stable.

    Someone mentioned Kawai grands and how they seem to "float" the pinblock. In a discussion with Don Maninno years ago he said they were designed and engineered that way and it shouldn't be a problem. In my experience, and I apprenticed at a Kawai dealer nearly 40 years ago, the pinblock fitting isn't an issue, though they may have others.

    Regards...

    John

    ------------------------------
    John Musselwhite, RPT
    Calgary, AB Canada
    www.musselwhite.com
    ------------------------------



  • 4.  RE: Unstable Grand

    Posted 07-07-2018 22:20
    Edited by Jon Page 07-07-2018 22:23
    Tapping the coils makes things neat but may not coax the coil tightly around the pin. Squeezing the coil and giving it a quarter-turn counter-clockwise four times insures that the coils is tight. Try a few, if there is no change in tension, it may be good to go (at least for those).

    Adding shims won't do much, since the bass and treble are OK. If there is an expanse of counter bearing felt, reduce the friction by installing counter bearing aliquots. That always works for me.

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

    Jon Page
    ------------------------------



  • 5.  RE: Unstable Grand

    Posted 07-06-2018 12:27
    Unstable in what way? Unisons still good, but pitch way off in the problem section? Or is it more that the unisons don't stay in tune?

    I bought shims at either Lowe's or Home Depot. I think it was Home Depot. Should be pretty easy to make some if you have the right saw.

    ------------------------------
    John Formsma, RPT
    New Albany MS
    ------------------------------



  • 6.  RE: Unstable Grand

    Posted 07-07-2018 10:24
    John, 

    The shims from the home improvement stores are a soft
    wood, usually some type of conifer. They will compress
    significantly once there is movement. While they are okay
    for construction purposes where all the other components
    are also soft, usually #2 pine, definitely insufficient for 
    this application. If you are using them, I would suggest
    you make your own out of scrap maple or pinblock instead.. 
    Hope this helps you.





  • 7.  RE: Unstable Grand

    Posted 07-07-2018 20:07
    The unisons are OK. It's the general pitch that is unstable.

    John

    ------------------------------
    John Musselwhite, RPT
    Calgary, AB Canada
    www.musselwhite.com
    ------------------------------



  • 8.  RE: Unstable Grand

    Posted 07-06-2018 12:55
    Shims can be almost any hardwood, maple, oak, beech, scrap pinblock material,etc. I make shims on my 5hp bandsaw. It don't have to be 5hp, I just like saying it. Lower the tension first. Apply some glue, tap them in. Try and make the shims the right angle (shallow)and thickness.
    Controlling the room humidity level is much superior than trying to isolate the control to the soundboard. I have several clients now that have switched from damp chasers to room dehumidifiers/humidifiers, all are happy they did. Much more consistency.
    -chris





  • 9.  RE: Unstable Grand

    Posted 07-06-2018 14:21
    a picture of the agraffes and tuning pin area in the problem area would be useful

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



  • 10.  RE: Unstable Grand

    Posted 07-06-2018 18:49
    John,
    Listed below are several ideas. Maybe one or none will help.
    Cut several 1 1/2”-2” shims out of hard wood. Yellow glue side next to pin block with yellow glue, tap the shim between flange and pin block tight and break off excess. Put as many as you want.
    This is a “piece of mind” project that probably won’t solve the issue.
    Check direct air flow, and consider a string cover and under cover. Lube the under string felt when tuning the beast.

    Sent from my iPhone




  • 11.  RE: Unstable Grand

    Posted 07-06-2018 20:11
    John,
    Many years ago I "epoxied" a Kawai pinblock to the plate flange; it was a disaster. The epoxy leached through the laminates and the resiliency of the pinblock was damaged. I had to replace the pinblock.
    Roger





  • 12.  RE: Unstable Grand

    Posted 07-06-2018 20:43
    I had an Asian grand on which the tuning was 'squirrelly". What I did to solve the problem was to use parallel pliers to grip the coil (at the becket) and squeeze while rotating counter-clockwise; four quarter-turns seemed to do the trick. The pitch of each string dropped anywhere between -60c to a minor 3rd. There was still a lot of slack around the coil. Solid tuning from then on.

    This primarily was in the top two section, but the center and bass had similar tension releases.

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

    Jon Page
    ------------------------------



  • 13.  RE: Unstable Grand

    Posted 07-06-2018 21:05
      |   view attached
    Does the middle section you refer to look like this Samick tenor section?   If so, inability to read the front segment, between agraffe and tuning pin will be a major chore...time intensive,unto hopeless.    Very high termination angle, bearing on a very long section of felt riding a radius up the slope...meaning, the string bearing and termination friction is out to lunch. ...that is, if this looks like your baby...

    On a non-flange fit block, I don't see the gapped area moving independently of the top and bottom sections, which you reported to be acceptably stable.

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



  • 14.  RE: Unstable Grand

    Posted 07-07-2018 07:30
    On a piano with a high angle of counter bearing, there is no finesse in tuning. You need to pull it to pitch and leave it. The friction is too great to finely manipulate the torsion in the pin. Aeolian's M&H and Chickering are this way.

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

    Jon Page
    ------------------------------



  • 15.  RE: Unstable Grand

    Posted 07-07-2018 07:53
    Timely topic! I just tuned a Young Chang G-185 yesterday - about 25 years old and in very good apparent condition. New piano to me. The owner said he had it tuned six month ago. The piano was close to pitch - 5 cents flat bass & treble, most of the tenor averaging a couple cents sharp with the lowest tenor notes up to 15 cents sharp. The unisons in the bass and treble were not bad for six months. The unisons in all of the tenor sounded like it had been at least six years since the last tuning - many 5+ cents off from one another. During tuning, most strings seemed to render quite well - very normal to tune.

    Piano is in a modern air conditioned and central humidity controlled home in central Florida. Piano is in middle of living room - no sun on piano, BUT an AC vent in the 12-foot ceiling blew air three ways, with the central bank of vents pointed directly at the piano. Lid is normally open.

    The owner commented that he was surprised that the tenor had gone out of tune so much in six months. I don't know who tuned it six months ago. We closed the vent pointed at the piano. I agreed with him that it is unusual for a piano to go so far out of tune in that short a period of time given the reported environmental conditions. I suggested that it was possible that the vent was the major cause of the tuning problem. It will be very interesting to see what kind of shape it is in six months from now.

    ------------------------------
    Terry Farrell
    Farrell Piano Service, Inc.
    Brandon, Florida
    terry@farrellpiano.com
    813-684-3505
    ------------------------------



  • 16.  RE: Unstable Grand

    Posted 07-07-2018 08:11
    Terry,

    My experience with that kind of tenor, and the picture I attached above (after the strings age a bit though)  is that though setting of the pitch and front segment tension seems clear and like you got it right, the feedback one receives from the segments was actually completely bogus. Older strings make this a hopeless scenario stability-wise.

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



  • 17.  RE: Unstable Grand

    Posted 07-07-2018 10:19
      |   view attached
    Thanks for the observation Jim. Next time I see the piano I'll consider that. Just by chance I do have a picture of the piano - I wasn't focusing on the front scale area of the tenor, but it was rather just a fun picture. You can't really tell the angle of the strings from the agraffes, but it doesn't appear to be as nasty as the Samick in your picture, IMHO. Difficult to tell for sure though.

    ------------------------------
    Terry Farrell
    Farrell Piano Service, Inc.
    Brandon, Florida
    terry@farrellpiano.com
    813-684-3505
    ------------------------------



  • 18.  RE: Unstable Grand

    Posted 07-08-2018 17:08
    So, if in reality, the problem is one of poor or incorrect  scaling (precipitous tension drop off), nothing you do to the pinblock is going to change anything.

    The fact that it has TP bushings negates the need to fit the pinblock, as you have 230 "flanges" sharing the load, and in fact literally tipping the pinblock AWAY from the plate flange under tension.

    My guess is scaling.

    Pwg

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



  • 19.  RE: Unstable Grand

    Posted 07-08-2018 22:13
    What about a missing plate horn wedge? Just worked on a grand that the wedge was oak, and I just replaced it with a steel one. Made me think of this post.
    -chris