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Restringing question

  • 1.  Restringing question

    Member
    Posted 07-29-2019 20:40
    Hello all,
    I am about to restring a 70s Yamaha G3 grand. I am restringing only due to rusty strings and pins as a result of being near the ocean for a number of years.  The tuning pins felt fine at the time of string and pin removal. I removed the old pins with a drill about 3 turns at a time to minimize heat.  I made several passes until they all came out. I don't know if that helped anything but it seemed like a good idea. The pins that came out are .270 and the holes are .267 as measured with a hole gauge.
    My question is this: What gauge pin did the factory use?  It is smaller than a 1-0 which is .276. What gauge would be best to go back in? A 1-0 or 2-0? I thinking a 1-0. Also wondering if I should use a gun brush before stringing?
    Does anyone have any experience with restringing with the same block and not for loose pins but only due to rusty strings?
    I've read a number of the forums but am still not totally sure which way to go yet.
    Thanks!

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    Cary Thrift
    Marietta GA
    770-517-9871
    ------------------------------


  • 2.  RE: Restringing question

    Posted 07-29-2019 22:52
    Only thing is to try some sample pins and see how they feel, after a couple of days. They will generally be tighter at first and then drop some...sometimes.

    I used to test pinblock scraps, but don't anymore, because the tests differ too much from the actual block. So, instead, to test, drive a couple of pins up at 88, 87 without strings. If you like the torque, after a couple of days, add the strings to the already installed pins(don't take out the pins, coil the string on a dummy pin as you would in an on-site string repair.


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



  • 3.  RE: Restringing question

    Posted 07-30-2019 06:37
    Jim I. wrote:  "I used to test pinblock scraps, but don't anymore, because the tests differ too much from the actual block."

    Were you using identical 
    pinblock material? I ask because I have been doing that for many years with very good results. Your idea up at #87 & 88 sounds good also, but the test piece should get one in the ballpark.​

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



  • 4.  RE: Restringing question

    Posted 07-30-2019 09:16
    Yep, I was using the same block material etc.

    The difference, for me, was, that since I drill in the (edit-drill in the piano not drill in the block whatever that means) with a dedicated pneumatic rig, my tests were done using a different drilling machine and different hold downs. Too many variables were introduced. The test pin, as I do now at 88, gives me the most reliable repeatable info I have gotten. One just has to prove you are reasonably in the ballpark to start with, which I would prove with a test piece, the usual way.


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



  • 5.  RE: Restringing question

    Registered Piano Technician
    Posted 07-30-2019 10:44
    Cary,

    Are you sure you don't have the numbers reversed? A .270" pin in a .276" hole will have no torque whatsoever (unless of course I'm reading this wrong).  A .276" pin in a .270" hole makes more sense to me, and I'm pretty sure that correlates to a 7mm pin. 

    At any rate, I believe 1/0 or equivalent has been standard for these pianos. I would probably go to 2/0 at least, though testing first as Jim suggested. 

    If you do brush the insides just be aware that it can remove more wood than you might think, so be careful and test with and without. 

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 6.  RE: Restringing question

    Posted 07-30-2019 19:15
    Jim I. wrote:  "...my tests were done using a different drilling machine and different hold downs."

    That'll do it!  I drill my test pieces with the same block material, same drill setup, same bit, etc., etc. - everything is the same - and I get consistent results.


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



  • 7.  RE: Restringing question

    Member
    Posted 07-30-2019 23:42
    I like the idea of testing on 87 and 88. Question for Jim and others . . . what torque are we looking for on the pin with the string off? What is the best way to accommodate for some expected torque drop?

    My understanding is that with the string on we are looking for at least 120 in-lbs clockwise and 60 in-lbs counterclockwise. 

    Thanks!

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    Alden Jack
    Smithfield UT
    435-760-3974
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  • 8.  RE: Restringing question

    Registered Piano Technician
    Posted 07-30-2019 11:43

    Cary,

    To begin with, Yamaha installs a 7.0 mm (.2755") pin at the factory. Yamaha parts department provides a 7.1 mm (.279") for oversize replacements. Because the typical supply house oversize pin is .282" (#2), that large jump in size from the original .2755" may pose a problem. Because you mentioned the original pins being good, I would suggest you use the Yamaha oversize pin. Also, Yamaha tuning pins are superior in quality in size uniformity and thread cut quality. Your removal technique is spot on – no excessive heat at removal. I use gun barrel brushes to clean the tuning pin hole although I can't, with certainty, attest that brushing will reduce the chance of jumpy pins, but I don't see any negative aspects to brushing and I have had no problem with jumpy pins since I incorporated that technique many years ago.

    Contact me personally if you wish to try a 7.1 mm pin on note 88 -- I stock them.

    Roger






  • 9.  RE: Restringing question

    Member
    Posted 07-30-2019 14:45
    Hi Roger, 
    I just talked to Yamaha. They told me they string new pianos with a 6.9 mm pin and offer oversize pins in .1mm increments. I didn't know that. Thanks so much for enlightening me! I'm going to try a 7.0mm and a 7.1mm and see which works the best. 
    Cary Thrift Jr
    Royal Piano Service Inc
    770-517-9871





  • 10.  RE: Restringing question

    Posted 07-30-2019 16:09
    One alternative in a situation like this is to use a straight fluted reamer to clean and resize all holes.
    I believe you can get them from Pianotek.

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
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  • 11.  RE: Restringing question

    Member
    Posted 07-30-2019 23:45
    Ed, when choosing to resize all holes, would you suggest turning the reamer bit slowly in a hand chuck or quickly with a power drill to get consistent results from hole to hole? 
    Thanks!

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    Alden Jack
    Smithfield UT
    435-760-3974
    ------------------------------



  • 12.  RE: Restringing question

    Registered Piano Technician
    Posted 07-31-2019 05:27
    Because I'm near the coast I do run into this situation a lot, i.e. restringing due to corrosion and not because of loose pins.  I do have some habits that are a little different.  Before I unstring the piano I sample the torque with string still on: top and bottom single unison, top bass, lowest wrapped string, and samples of each section.  Since anything you do from this point on will lower the torque, I'm looking for the lowest torque I can find and usually this is in the bass section, single unisons.  Note 88 will almost always give you the highest torque you'll find.  I'd rather err on the side of having things a little too tight after restringing.

    If the lowest torque find in the bass is within range, I would just go up one size from there, from a 2 to a 3 say.  However if the bass section is sloppy, which you find often in older instrument, I would go up 2 sizes, one size to take up the slop and other to compensate for the looseness you introduce in the act of prepping the pinblock for the new pins.  You can either do the whole block that way for the sake of consistency or just use a larger pin in the bass if you find the torque in the treble section is adequate.

    There are a few things I do to prepare for installing the new pins and wire, all of which have a net effect of lowering the torque, hence the need to go up a size.  First I power out the existing pins after breaking the beckets,  finding it too time consuming to slow walk them out.  Even cranking them out will lower the torque somewhat.

    Secondly, before I restring I drill out the holes with an original size bit. (Or one size smaller than the pin you're going to be putting in, if you are going up 2 sizes.) This is because I usually find that at the bottom of the holes there is an appreciable amount of shrinkage of the hole size.   Whether this is due to hole swelling up due to moisture in the open exposed area beneath the pin or whether the very act of driving in the pins pushes a kind of wave down the block ahead of it, I couldn't say.  Perhaps a bit of both.  However, I don't want the pin to be tighter at the bottom than it is at the top, which encourages it to twist and makes tuning unpleasant. Because you are in effect redrilling the hole with the same size as was originally used you won't be removing that much wood and the bit doesn't heat up appreciably so you can go fast.  Keep in mind though that even though the bit won't meet much resistance in the top of hole it will have the net effect of lowering the torque somewhat.  Don't use a brad point bit for this but one with a traditional rounded tip.

    Thirdly, I do use a gun brush like this: push in straight down, then a half twist as you pull it back up and out.   No more.  It's easy of overdo it.  Be consistent.

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    Cecil Snyder
    Torrance CA
    310-542-7108
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  • 13.  RE: Restringing question

    Posted 07-31-2019 08:38
    I put it in a T handle and clean each hole gently. You're not removing a lot of wood, just scraping the surface clean and evening out the diameters. It will take less than an hour, but you'll probably want to pause to rest your wrists.
    I'm recommending straight fluted reamers, not spoon reamers.

    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------