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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Original Message:
Sent: 07-30-2019 23:45
From: Alden Jack
Subject: Restringing question
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
Original Message:
Sent: 07-30-2019 16:08
From: Ed Sutton
Subject: Restringing question
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.
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Ed Sutton
ed440@me.com
(980) 254-7413
Original Message:
Sent: 07-30-2019 14:44
From: Cary Thrift
Subject: Restringing question
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
Original Message------
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