There is also a little tool that can work without removing the action and avoiding unscrewing the knuckle, but with flat knuckles, it isn't very convenient.
As a rule, one usually acts:
1) using the lamp to heat the stylus to straighten a crooked hammer if it rises correctly, i.e., equidistant from the two neighbors as has been rightly said (be careful not to burn the stylus; it is heated by moving it back and forth with the flame under the stylus while applying torsion to the hammer)
2) using paper strips if it rises crookedly; generally, they are checked by making them rise in groups, helping with a small bar that you hold in your hands and place behind the hammers to pull them up together. Meanwhile, you visually observe if any of these approach or move away from the adjacent hammers while rising.
3) orienting the knuckle if the hammer is not centered
In the Kawai manual, it seems to me they explain these operations, although how to perform the checks can be a bit unclear.
It takes a bit of patience; Pianoexpert was right to make this clarification because I was a bit superficial in taking some things for granted.
It is difficult because the technician should not be seen as a leech but as a trusted person, and fortunately we have many good technicians in Italy, some better as mechanics and others better as finishers.
Often dissatisfaction arises from a misunderstanding.
I agree, if you do not trust your technician, you are prone to thinking that the Piano is never in good shape.
Over the years I have had to deal with, unfortunately, also technicians of that type, but for a long time now I have had one who is very understanding and available and who enjoys my complete esteem.
However, there are people (like me) who need to test certain adjustments and then perhaps return everything to how it was before, as I have done these past few days. In these cases, you cannot always have the technician at home and you use DIY, provided you are familiar with tools and various disassembly/assembly tasks.
I like this exchange of advice of yours, which is moreover correct and constructive. I just wanted to clarify that if the hammers in question start well spaced apart and arrive still well spaced apart, you should not add paper under the forcola, either on the right or on the left. The paper must serve exclusively to deviate and straighten the stroke of those hammers that rise with a deviated stroke. Pure and simple centering can be modified by loosening the screw of the forcola and moving it to the right or to the left. Good work
Thank you Paolo for your clarification.
The situation is what you described: the hammers start and arrive well spaced apart.
A question: the forcola seems to me to rest on a track, is there a minimum amount of left/right adjustment space?
As he told you, if you unscrew it and move it a little to the right or left, you should be able to manage even if the washer has made its seat on the bridge. Try it, it's only a little bit, right?
So: one thing is using paper templates to deviate the stroke and another is using the flame. Yet another is acting on the screw to adjust spacing. One must first see if the hammers are deviated when rising. Once the deviation is corrected with a template to the right or left, we will notice that the hammer is slightly tilted. Then, with the flame, but without burning the shank (if it is an alcohol flame, it is better), one acts by heating and simultaneously "gently" twisting the hammer while passing the flame. Wait a few seconds for the shank to cool. This serves to make the hammer in question parallel to the adjacent ones, even if not well spaced. Now we will notice that the hammer is slightly spaced compared to the others? If so, we will act on the screw and recenter it. This is the correct sequence. The important thing is to start from the parallelism of the hammer stroke, checking that the reference hammers strike the strings simultaneously, meaning that the surface of the hammer tip is perfectly parallel to the strings. A good indication of marked hammers is that all grooves have the same depth. An important thing is to recreate this parallelism when a hammer shaving is performed (which I am almost always against). Good luck with your work
