II. THE TOP ACTION (off the keyframe) - continued
22) Clean repetition spring and groove (Steinway, Yamaha, Bosendorfer). On Steinway, Yamaha and the Bosendorfer whippens (which have the butterfly type repetition spring), the spring grooves are coated with a graphite solution. The Yamahas now use a teflon coating here, but the older models of this type whippen are graphite.
Hurray that someone has finally seen the light! This graphite paste becomes dirty and gummy, and makes for a source of friction instead of eliminating it. These grooves in the underside of the balancier and the spring tips must be cleaned in order to achieve a good regulated action. If left uncleaned, the jack height is very hard to set since the repetition spring not only has to support the knuckle, but also has to overcome this messy graphite paste as the balancier moves.
To clean this groove, release all 88 repetition springs from the grooves and turn the action upside down, taking care to protect the hammers while doing so. Run a piece of cloth up and down the grooves until clean. Be careful not to damage the groove. Now choose a lubricant which will, hopefully, eliminate this problem during future use. I have tried three different lubricants for this job, but I have reservations about all three of them. If any of the readers have a sure-fire method to solve this problem, please be kind enough to share it!
I have tried:
1) Dag 154. This is a graphite solution and works well for lubricating the spring. I question whether it will be free from the dirty, gummy mess which plagued this area in the first place.
2) Spray teflon. I feel that this teflon is not as good as what is available to the manufacturers. It does not seem to last. Hence, the repetition spring, while not getting dirty and gummy, will also not be lubricated quite well enough.
3) White grease. This is supposed to prevent rust and corrosion on the spring. It is not absorbed into the wood, but it is bound to get dirty with time. As to whether it will also get gummy and inhibit the spring is anybody’s guess. The ideal would.be to apply a teflon coating like what Yamaha now uses, but to my knowledge this is not available to technicians.
Turn the action right side up and clean the tips of the repetition springs with a suede brush. Rebend the springs back into their grooves, making sure that the spring is indeed in its groove by applying as light sideways motion.
23) Round whippen felt if needed. The cushion felt on the bottom of the whippen which rests upon the capstan always compacts and gets worn from the constant hammering of the capstan hitting against it. Incidentally, this compacting along with the flattening of the knuckle is why a new piano always loses its hammer line. In the case where these parts have only “settled in”, the action can be brought back into regulation by raising the capstans and making the corresponding adjustments in the let-off and drop. Since raising the whippen puts the jack tender closer to the let-off button and the balancier closer to the bottom of the drop screw, these two must be changed.
I use two wear areas, the knuckle and the whippen felt, to decide whether to repair an action or to replace the action parts. Just like a flattened knuckle, a worn whippen cushion felt must be replaced. I find it far less hassle to just replace the whippens and shanks/ flanges instead of taking the time to try to repair these parts. But, if the piano is obsolete or if only a little worn, the whippen felt can be rounded back to its original shape by passing wool yarn through it just like as in rounding aworn knuckle. In the.case where the whippens are obsolete and the cushion felts are deeply grooved, then the only solution is to replace just the whippen felt. I might add, that if such a piano was thrown into my hands, I would try to procrastinate doing the work until the owners junked the piano!
24) Polish the capstans. The top action is still off the keyframe, so the keys are readily accessible. Either buff them on a buffing wheel or if on the job away from the shop, take some chrome/ metal polish along with a rag and polish them a section at a time. Just use a wooden block along the back of the keys to keep them level and from wiggling too much. After polishing, I like to spray the capstans with emralon.
25) Clean knuckles and backchecks. A good shop will have a portable air compressor as a part of the essential equipment. Take the nozzle and blow with high pressure up and down the knuckle and backchecks. Of course, it goes without saying that the entire action should be blown out, but I like to use a higher pressure when cleaning the leather. If the knuckles are dirty with graphite, this must be cleaned off next. Use some sort of a solvent, whatever is available in your area (some say that Renuzit is still available, but I can’t get it). Then take a suede brush and comb the leather. Check the hammer tails. If they are not rough enough to ensure good backchecking, use a hand file and correct. Be careful not to roughen the tails so coarse as to wear the back checks abnormally.
This ends section II. Before proceeding onto section III, make sure that all needed repairs have been finished and that sections I and II were performed accurately. Remember that if two people are working in the shop together, one can do section I while the other works on section II.
III. ALIGNMENTS (install action back on keyframe)
26) Align action frame in piano (adjust keyframe stop block). The action parts must all line up to insure full power and reliability. Take as samples the action parts to the keys at the ends of each section. Starting at the strings and working down, align the parts to the strings. This is assuming that the strings are in proper alignment. If the piano has been restrung, or especially if the plate has been removed, this may not be the case. Where there are agraffes or some other string positioning devices, you can be pretty sure that the strings are aligned well, assuming the plate is OK. Too many “technicians” try to install pinblocks and soundboards when they do not know how to align them. If you have trouble aligning the action and can see the piano has been “rebuilt,” the problem may be that the piano was not properly rebuilt. Anyway, loosen the hammerflange screw to align the hammer to the string. Next, align the balancier so it is directly underneath the knuckle. This is done by either loosening the whippen screw and tilting the whippen or else shimming the flange and rotating the whippen. More will be said on this subject in step 28.
After the sample keys are aligned, check to see how the hammers look in relation to the strings. If all of the hammers are off to the left (most usually) or off to the right, then the stop block at the left end of the keyframe must be adjusted. It normally is screwed into the case, so just remove it, install or subtract shims, and screw back.
Shimming the stop block is normal, because the felt often compacts from the action coming back after using the una corda pedal. Make sure you check this if the piano has been stored for a time on its side, since the weight of the action against the stop block compresses the felt. If the shims need to be removed, as would be the case if the capstans are off to the right, be careful. Something has caused this and should be corrected.
There is the far chance that the action was improperly aligned in the factory, but not often. If the hammers have been replaced poorly and the hammer angle or hammer travel are way off, check here. More likely, check to see if the pinblock has been replaced. If the string alignment has been changed through altering the plate, not only will the action not line up, but the dampers will not, and the sidebearing on the bridge pins will be excessive.
As a caution, check to see if the capstans were centred in the keys, or that the keys are properly spaced and not warped on the samples being used. Is the action positioned on the keybed correctly? Since the bass strings cross the tenor at an angle, pulling the action in and out will change the hammer to string alignment a little. As a final check, did you rotate the whippen flanges when they should have been tilted, or vice versa? Remember to favour the strings which have agraffes when choosing where to align, since the upper treble strings with a V-bar can be slightly aligned to the action.
Kommentare