Kuerti article, part II (long)

[Jim Harvey]

Hello Margaret,

Thursday, March 4, 2004, 11:38:06 AM, you wrote:

CEH> About the repair suggestions by Mr Kuerti, not all of them
CEH> are entirely bad.  It is commonly advised to burnish rather than
CEH> file the balance & front pin holes by restorers and those dealing
CEH> with reproduction early keyboards.  The tightness here (except
CEH> maybe in cheap new pianos with poor keyboard wood) is often
CEH> humidity caused, and to actually remove wood with a file is
CEH> inviting looseness later.  I'd think the heavier the keys, like
CEH> modern piano keys, the more problem this would be.  I think
CEH> European technicians are taught to burnish (an awl works as well
CEH> as anything).   This presumes the keys are fitted and eased
CEH> properly at the factory, which is probably not true with many
CEH> quickie spinets etc.  But we're talking well-maintained concert
CEH> pianos here I think.

Margaret, I can't speak to all the repair suggestions, because I have
yet to read either segment in entirety. Even then, I won't add more
fuel to this. My post was more of a global caution to newer
technicians about the use of dated material, -not- one of challenging
the author or the article's contents line by line. I hate to think
what will be made of my articles -- and posts like this -- after 30
years, but it will probably be something like "Who was this Harvey
idiot, and at what point did he fall off the truck"?

Likewise, I have no issue with your reply up to the point of 'an awl
works as well as anything'.

There is a reason why Yamaha's CF tool is used only by seasoned
technicians in Japan (at least that's what Kenzo Utsinomiya[sp] once
told me). There is also a reason for George D's method of using the
Nicholson files with two opposing safe sides. One method is from the
top, the other from the bottom. Neither method represents inserting a
symmetrically round or perfectly conical shaped object into the key.
Another example would include Jack Krefting's PTJ mention of using a
balance rail pin of the same size as those currently in the action,
and swedging (swaging for some of y'all), or hammering one end of the
pin to a slightly out-of-round condition.

That's three separate methods (so far) of accomplishing essentially
the same end result, other conditions notwithstanding, and all tools
feature the same feature in common... two relieved sides.

If one diagnoses sluggishness as a result of balance hole friction and
then closely observes the balance hole prior to applying [whatever]
remedy, it will often be apparent that the hole has grown from round
into an oval or 'egg' shape'. Usually the front to back portion of the
hole will be okay, but the sides of the hole will have swollen, thus
acting like a tiny vise against the key pin. The theory portion can be
challenged, but deals with wood swelling/shrinking in the direction of
grain, or some such. Don't want to go there, since I'm having a
senility attack at the moment.

Our objective, by whatever method, is to restore the hole back to
round, allowing just enough margin that key motion is not influenced
(restricted) by excessive friction. Whether this is due to the wood,
manufacturing methods, or humidity is not our immediate focus
(although they each have a bearing on the chosen corrective
procedure).

Unless I'm missing a trick, it occurs to me that if an awl (in the
Biblical sense) is inserted into the balance hole (compression
method), by the time the tool has penetrated far enough to alleviate
friction on the sides, the -entire- hole has been enlarged. This not
only defeats the objective, it reverses the original problem. I once
witnessed this on a brand-new piano. The keys went from 'new' piano
snug to pulley, sloppy, and rattling, all within the few minutes
required to perform the operation. To reflect on Kenzo's wisdom, this
is why they don't permit the newbies to use the CF tool with reckless
abandon. Even though the CF tool has safe sides, the same kind of hole
deformation could result from improper use of the tool, lack of
tactile sensitivity, or my favorite... "If some is good, more must be
better" attitude.

Admittedly, none of this reply addresses the inside mortice of the
balance hole, and therein lies the basis in support of burnishing
versus filing.

I could extend this wordy reply with comments on fitting and easing at
the factory level, but will save that for another time.


--
Regards,
 Jim
             mailto:harvey@greenwood.net