The action is first cleaned thoroughly with an airgun with the aid of a brush and set up on the bench for dismantling. All the parts are numbered in pencil from bass to treble.> Hammers are numbered on the small square portion on the top of the catcher. Similarly the wippens are numbered on the small square end that faces the strings. Damper assemblies are numbered on the levers. I always number the main action rail in steps of ten to ensure that the components go back in the right place! There must be many cases where technicians have put on a row of hammers only to find they are "one screw hole out".
Everything comes off the action and goes into various trays with their screws. If the bridle straps are rotten and difficult to unhook, then they are just broken off, trimmed off properly later and a new set fitted - no point in messing around here. When I am busy, I usually engage a capable person to do all the dismantling.
I closely examine the leathers and felts for wear and replace items such as badly worn butt felts where necessary. Perhaps some flanges may need rebushing, but in a good instrument I would not expect this, and would be reluctant to do a complete rebushing job on most pianos. I would consider a flange to need rebushing if the required pin was larger than 1.38mm. The possible need for any of this work would have been allowed for in my quote.
Removing the pins is done by an excellent bench tool that I have had made for me. One steady push with the lever and out comes the pin. As each flange is done, a new pin is selected and fitted there and then, so each component has its original flange. The extracted pin is measured with a micrometer and a pin the next size up is used. The bushing is reamed out using a broach made out of a slightly roughened pin that is the same size as the extracted one. I have a set of these broaches which are held by appropriately inscribed pin vices. The bushing is reamed until the initial grip on the broach is reduced - only experience has shown me exactly how much. I try to avoid using a tapered bushing tool as I don't feel they are precise enough. After the reaming, a polishing of the bushing is done lightly with a burnishing tool.
The selected new pin (one size larger) is tapped in, taking care that it goes through the birds eye in the hammer butt and not to one side. Very sharp pins have a tendency to make their own hole - disastrous. I use a flat piece of wood with several holes in it to act as a recess where the protruding pin can go when it is tapped in. The pin is driven through a fraction further into the flange than flush. This is so when the pin is cut on the other side it can be tapped back a little so both sides are now flush. The tapping will also flatten the nicked end of the pin so it won't catch on the adjacent one. However, I prefer tapping the pin flush with the bushing and filing the cut end smooth.
The flange can now be checked for free movement by holding it and swinging the hammer like a pendulum. It should swing two to three times. There are texts that suggest putting a screw through the hole of the flange, and if the weight causes it to slowly drop, the movement is about right. Personally, I believe that this would indicate that the flange is too loose. A better test that I was shown years ago is to hold the flange with a pair of pliers and wiggle the hammer while holding on to it with your fingers. If there is the slightest amount of play, it will be felt - not seen - felt. The tests mentioned here assume that we are repinning hammers, rather than jacks and wippens. This is quite appropriate, because it is the hammers where the correct pin tightness is the most critical. If too tight - they stick and if even slightly too loose - they wobble badly.
My experience has shown that repinning is better to be done slightly on the tight side rather than too loose. If I fail to ream out a pin sufficiently and the flange is too tight, it can be gripped tightly with the fingers and slid from side to side a few times to possibly free it up - otherwise it has to be redone. Slightly tight repinning tends to free up a little where slightly loose repinning can only get worse!
I go by metric measurement rather than "sizes" with the most common pins being 1.35mm and 1.38mm. Most good actions will have a consistent size throughout the various sections, so once the first few flanges are done, further measuring is usually not necessary.
Once all the hammer flanges are repinned I then usually fit them straight back on to the action, making sure where possible that any packing tape on the flanges is undisturbed to ensure the original alignment (which may however have to be adjusted later). It is easier to fit the hammers before the wippens because the jacks are not in the way. Once all the hammers are fitted, I wiggle each one individually side to side. Apart from the flexing of the hammer shank, there should be no movement. If some do move, which is quite possible, I first check to see if the flange itself is properly screwed to the rail or in the case of the older brass type, that the screw securing the pin is tight. If it is the pin/bushing combination that is at fault, this is the best time to re-do them while the wippens are still off.
The wippens and jacks are then done using the same methods as above followed by the dampers if repinning them is required.
This is obviously labour intensive work, so rather than take it on all at once, I usually stretch it out over three weeks, doing more routine work in between.
An appointment is now made and the action is placed back into the piano. If everything is done as described, the action will work freely. When it comes to determining what regulating should be included in the quote, I ask myself "in doing this recentering job, what have I changed?". I then only commit myself to those areas. A certain amount of regulating will be required, such as alignment of hammers and dampers. The bridal tape wires will also need adjustment. As the keyboard is not involved in this exercise, I would not be inclined to adjust it without charging extra.
Recentering a piano action takes many hours - for me, around fifteen and I would charge a reduced hourly rate to my customer. A typical piano action overhaul as described here would be charged out at $1200.00 (2008). At the completion of the job, the customer is often pleasantly suprised to find that the piano is then to be tuned at no extra charge.
Brian Holden 2008