Having discussed section I, The Keys & Keyframe, last month, we will continue with section II, The Top Action. Note that those procedures covered recently elsewhere such as rebushing, steaming warped keys, repairing the balance pin hole, etc., will be skipped over in this guide to regulation.
Also, some procedures were skipped over which were not covered elsewhere, such as refelting the keyframe. These I intend to discuss at a later date. If any reader feels I have neglected or passed by a subject, please let me know.
II. THE TOP ACTION (off the keyframe)
15) Check action centres, repin or shrink as needed. There are many tests which can be used to determine if the action centres are too tight or loose. Lets discuss the hammershank / flange centre first, since it’s by far the most important and the most troublesome. I will list the six checks I regularly use for this centre:

A)   Wiggle each hammer gently side to side and feel by hand if the centre feels loose.

B)   Similarly, insert a long screwdriver blade under the shanks and wiggle the blade from side to side. Watch the hammer for any sign of lateral movement. Any movement indicates a loose centre.

C)   While the screwdriver blade is still under the shanks, lift all of the hammers in a section up and quickly release the blade downwards. Any sluggish centres will be late in following the blade down.

D)   With the screwdriver still under the shanks, block the blade up at both ends so the shanks rest on the blade, preferably right on top of the rest felts/rest rail area. Individually raise the hammer and let it fall on the screwdriver blade. Listen closely to the sound upon impact, and watch how much bounce the hammer takes. Too little bounce indicates a tight centre. A noisy impact of the shank upon the blade indicates a too loose centre. This noise is much like striking a baseball bat upon the concrete and listening for a crack in the wood.

E)   With the action firmly in hand (preferably screwed down to the keyframe) put the action on one end and swing the hammers out away from their rest position and back. Any sluggish centres will be noticeable by the lack of movement.

F)   And, of course, the best method is to unscrew the flange and check the swing of the hammer by hand. Take the flange in one hand and hold it vertical, the hammer being taken by the other hand and raised to a horizontal position, 90” from the flange. Holding the flange very still, release the hammer and watch how many times it swings under the flange. This will look much like a pendulum. Count the number of passes the hammer makes under the flange. For this centre, seven or eight passes is considered excellent. If the piano is a Steinway with teflon bushings, then the best results are at five or six passes. Fewer passes indicate a sluggish centre or a bent centre pin. Greater than eight passes indicates a loose centre or some other problem such as a crack in the shank at the bushing area.

Unscrewing all 88 hammers may seem like a lot of work, but it is the only way to know for sure how every centre is working. If the piano is used for concerts, then plan on taking every hammer off and checking the centres from time to time. This can mean the difference between the artist praising you and the piano for an even and responsive action, or criticism for a piano that has a heavy touch, was uneven, or would not repeat.
This is not as much work as it sounds. Just make sure the hammers are all properly spaced to the strings before you begin, and the whippens and backchecks are aligned to the hammershanks and tails. Take off all of the odd numbered hammers and work on them. Replace them and realign them using the neighbouring hammers and the previously aligned whippens and backchecks. Go on to the even numbered hammers and complete the job in the same manner. Recheck the hammer to string alignment and you are done.
Now let’s talk about repinning action centres.
I highly recommend using a pin vise which is capable of extracting and installing centre pins. If you work on Steinway teflon bushings very much you will notice the extractor pin is a little large and often ruins the teflon bushing while .removing the old pin. Just remove the extractor pin and turn it down, using a drill and wet/dry sandpaper.
While we are discussing Steinways, be sure to purchase from the factory the set off our reamers. These can be used with equal success on regular felt bushings. Remember Steinway uses a rolled pin slightly rounded on each end. Oversized rolled pins can be purchased from the factory. Also available from the factory is a kit with both sizes of teflon bushings and oversized centre pins. Regardless of what can be said pro or con about their new bushings, their rolled pin remains superior, I use this pin in regular felted bushings as well as in Steinway centres.
Think for a minute about what happens when we use a regular centre pin. In the process of cutting off the excess pin, the pliers squeeze and make the pin oblong at the end.
Depending upon how sharp your pliers are, you also leave a burr, either large or small. Some technicians file down this end of the pin to correct the burr and oblong end. Great, but this still can leave the edge of the pin sharp enough to eventually cut into the felt bushing. This filing also takes time. If it only takes an extra 20 seconds, this means an extra half hour to repin and file a complete set.
Other technicians cut the pin off a little ways away from the side of the shank, so that the burr does not have contact with the bushing. This looks tacky and can result in the pins touching each other, making it hard to align the flanges. For what little more the Steinway rolled pins cost, I always use them to save time and to eliminate any chance of ruining the bushing. It also keeps the job looking neat by not having the centre pins sticking out from the bushings.
To conclude our discussion on action centres, let’s compare repinning versus using solutions or the “zapper.” If a centre is loose, we have no choice but to repin, unless we want to take the time to rebush the shank. If the centre is sluggish we can: 1) remove the pin, ream the bushing to the proper tolerance, and install a new pin; 2) apply a lubricant to make the centre “work easier” (the only two I know of as being the correct lubs for the job are an 8:1 solution of naptha / mineral oil and an 8:1 solution of naptha / silicone as sold by the Wurlitzer people); 3) apply an action shrinking solution such as water / alcohol or the solution as outlined in the Baldwin service manual; or 4) use electricity to heat the centre pin, causing it to dissipate moisture from the bushing and causing the fibers around the pin to be “ironed,” better known as “zapping the pin.”
Of these four methods, only the reaming and the “zapper” are instant in their results. Applying solutions can mean awaiting time of up to 24 hours, depending upon the solution used. None of the other three methods has been shown to be as long lasting as reaming.
If the centre to be treated is actually frozen, meaning the hammer swings two arcs or less with the pendulum test, the only permanent solution is to ream the bushing. Using the zapper on a frozen centre usually results in cooking the birds-eye hole in the flange. Using a shrinking solution on frozen centres is always time consuming and rarely permanent. Lubricating a frozen centre is a complete waste.
For sluggish centres – that is, ones which swing three to six times – it is dealer’s choice which of the four to use. Just try to pick the best method considering time, season of the year, cost to the consumer, and previous knowledge of how the methods work in your climate. If undecided, ream, for that is the most permanent.
When repairing action centres other than the hammershank / flange, remember all of the other centres are supposed to be more loose than the hammershank. Going in descending order of tightness: hammershank, whippen, balancier, under lever flange, jack, underlever top flange, and sostenuto tab. In recommending a good test for these other action centres, I would begin by saying, let well enough alone if nothing seems wrong. Obviously, if a centre pin has worked itself out and is causing a loose flange, repair it. Or, if encountering repetition problems, it looks like a certain action centre is sluggish and thereby causing slow repetition, remove the offending part and repair as needed.
As far as useful tests, a sluggish jack can easily be tested by lifting up all of the hammers and looking at the top of the jacks. A sluggish jack can be spotted by finding a jack which has not returned to its rest position, and so is out of line with the other jacks. The sluggish whippen, balancier, and damper centres are a little harder to test. Try moving the part with a finger or screwdriver and check for undue resistance. Just remember each time a centre pin is removed from the birds-eye, the hole is enlarged a little and the same size pin reinstalled will not be as tight as the original. So do not extract a centre pin unless it needs to be.
Now that we have spent this whole article on action centres, the remaining procedures of section II, The Top Action, will be discussed in the next post. If nothing else is remembered about action centres, make sure the centre pin is tight in the flange. The pin rotates freely in the bushing, not in the birds-eye.
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