Grand Regulation In Detail - Part 3

In this third part of our grand regulation guide, we will continue with discussing the Section II, The Top Action. Remember that action centres were discussed last week, so now we will begin by talking about hammer traveling, which is Point 16 on the 50-point checklist.

Point one on the checklist was tightening all of the screws. Now if all of the foreign material was cleaned out from under the flanges, usually by using compressed air, we are now ready to travel the hammers. What we are looking for is a hammer that swings to one side as it is raised from the rest position to normal striking height.

I find it best to use a long rod such as an old pedal rod in traveling a whole section of hammers at one time. Insert the rod under the hammershanks near the hammer, at about the rest felt/rest rail area. Hopefully the rod is long enough so the ends will protrude over into the next section of hammers. If not, make sure the rod rests on at least one shank at each end so as to be level.

 

If any hammers are badly angled (Point 17), I find it easier to correct these first before traveling. On the other hand, if the hammers are traveling way out of alignment, then it might be easier to travel first, angle later. Anyway, keep in mind that a travelled hammer must be angled in order to keep the striking surface square to the string, assuming that the striking surface was square in the first place.

To find hammers that need traveling, lift the rod up and down approximating the hammer-to to string distance and watch for hammers moving towards their neighbours. All hammers should lift vertically, with no sign of movement to the right or left. If necessary, use a square or a board with vertical lines drawn on it as a guide to make sure the hammers all lift perfectly straight. Without the use of a guide it is possible to travel all of the hammers, but end up with them all moving slightly to the right or left. Any horizontal movement will result in a loss of power, abnormal wear on the hammer and its bushing, and voicing problems. Do not bother to travel the hammers any higher than a few inches, since they do not function any higher in the piano.

Any shanks which are moving to the right or left are corrected by placing a thin shim under the flange so the shank will travel vertically. The rule is to place the shim on the side of the flange toward which the hammer is traveling. In other words, if the hammer is moving to the right, place a shim under the right side of the flange. I prefer to take the flange off completely and place a gummed piece of paper such as packing tape or a strip of masking tape as a shim. This works better than just a piece of newspaper so often seen here, since they stay with the flange whenever it is removed in the future.

 

Also, in taking the flange off to shim it, I always check it to see if some foreign material is causing the hammer not to travel correctly. If more than two shims are necessary, filing the flange on the opposite side is preferred to installing many shims. In really bad cases, rebush the centre.

Since shimming the flange actually tilted the hammer, now we need to go back and correct the hammer angle. In case you do not know what I mean by hammer angle, it is correcting those hammers which are leaning to the right or left. Do not confuse this with the angles which the hammers are glued on to so that they are aligned to the string angles. This is in a different plane. The angles we are talking about are caused by the shank warping or by shimming the flange to correctly travel the hammer. To correct the hammer angle, take a heat gun or an alcohol lamp and heat the shank by quickly passing the heat up and down the length of the shank.

At the same time, apply a tilting pressure to the hammer head in the direction it needs to go to correct the angle. You will feel the shank twisting when it gets hot enough. Don’t burn the shank! Keep in mind that some pianos are designed for the hammers to be slightly angled a couple of degrees in certain sections, usually the tenor or bass. Note that if the same rod is used here in angling that was used in traveling, the hammers will all be uniform in height (remember that we have not got to regulation yet) and therefore easier to spot those which are misangled. Do not lightly pass over these two procedures, as they really make a difference when it comes time to voice the piano.

Next on the checklist is Point 18, reshaping the hammers. At some time in the future, we will discuss when to tell if the hammer has enough life left in it to reshape it or if it needs to be replaced. As this post is based mostly on reshaping in the shop, we will also discuss in the future ...

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Grand Regulation In Detail - Part 2

Having discussed section I, The Keys & Keyframe, last week, 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 ...

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Grand Regulation In Detail - Part 1

In the last post, we discussed a 50-point checklist to be used in regulating grands. Last month we printed a grand regulation chart which shows how each of the nine regulation steps directly affect the others. Now in combining these two concepts, we will go through each of the 50 points in the checklist and explain in detail to how perform each step.

I. KEYS & KEYFRAME

 

1) TIGHTEN ALL SCREWS, REMOVE ACTION AND KEYS

 

Before anything else is done to piano, all of the screws should be tightened. This includes the screws, case parts, action parts, lyre and damper assembly parts. This is to insure that everything that should be snug and tight is, eliminating any noises or excess wear which could crop up from loose fittings. It also insures all of the moving parts are in correct relationship to each other. When tightening down the plate use a large screwdriver has had the tip ground to fit the plate screw heads. The whole blade should fit the screw head, not just the corners of the blade. I use a Sears 3/8” Craftsman which has a square shank, enabling me use a crescent wrench on the shank to help turn the screw. If this method is used, be sure to put your weight on the screwdriver to keep from ruining the head of the screw. Do not turn plate screws more than ½ turn at a time, and skip every other screw. Otherwise, it is very easy to flex the plate running the risk of possible plate breakage. Do not attempt to change the nose bolts unless something is obviously wrong, such as the bolt coming loose in the beams under the soundboard. Nose bolts are not to be tightened to achieve more downbearing. Tighten all action and case part screws hand tight. Overtightening will only crush the wood or else result in a stripped screw hole. On aluminium action rails, if the hole is stripped, a larger, self-tapping screw will solve the problem. Do use common sense and refrain from tightening screws which are adjustments to action mechanisms. These include the drop, let-off, jack regulating screw, jack stop rail, repetition lever and spring screws, cheekblock adjusting screws, etc.

To tighten the action screws, the action must be removed from inside the piano. Take care not to depress any of the keys when pulling the action out, or a broken hammer shank will result. Place a hand on each end of the keyframe and pull the action out slowly. Now remove the action bracket screws which hold the stack into the keyframe. Some actions have the front screws (nearest the keyboard) slanted at an angle. These are removed first and installed last. Make sure you have some method for returning the action screws back into their original holes. Set the stack aside and remove all 88 keys. To keep from enlarging the balance pin hole on the bottom of the key, take hold of the key at the back as well as the front and lift off evenly.

2) SAND KEYBED, APPLY TALC OR SLIPSPRAY

The ideal match between the keybed and the keyframe is for both to be perfectly straight and level. Otherwise, when the keyframe shifts, high and low spots are sure to occur, resulting in noises. Therefore, sand lightly the keybed to give it a level, smooth surface upon which the keyframe can slide. Also, apply talc, slipspray, or some other substance to help the keyframe shift quickly back and forth. A straightedge may be helpful in finding high/low places.

3) SEAT ACTION ON KEYFRAME, REPAIR STRIPPED SCREW HOLES

 

Seating an action frame is an often overlooked procedure. The keyframe should be straight and flat on its underside to match the keybed. If the action brackets have any amount of space between the bottom of the bracket and the top of the screw hole on the keyframe, a warped keyframe will result when the brackets are screwed down tight. Of course, if any holes are stripped, drill-plug and redrill. Cross-threading the screw holes can be eliminated by starting the screws by hand or by turning the screws backward until it drops into the threads.

 

4) BED KEYFRAME: BACKRAIL, FRONTRAIL, STUDS; SAND AS NECESSARY

 

Now that the stack is on the keyframe without the keys, back up the balance rail bedding screws (make sure you get the ones only visible from underneath on Yamahas) and install the action into the keybed, securing the cheekblocks. The cheekblocks should apply a small amount of pressure to the keyframe to keep it down, but not so much as to cause it to raise in the middle. A perfect fit is when the shift pedal works freely with the keyframe secured on the key keybed. Bed the backrail first, then the front rail, lastly the balancerail studs. The correct specification here is to not have any spaces between any of the three rails at their point of contact with the keybed, both in the regular and in the shift positions. When bedding the front or backrail, tap on the rail and listen for knocking noises. Mark offending areas with chalk. If the knock is at the ends of the front rail, the cheekblocks were not fitted correctly. If the knocks are at the middle of the front rail, try to loosen the cheekblocks to see if they were too tight. If not, then lift the front or backrail up enough to places and paper strips grit side up under the contact points on each side of the chalk marks. Draw the sandpaper out and recheck the area for knocks. Remember that the area to be sanded is not where the chalk marks are, as these are the high places, but rather the low places surrounding the chalk marks. Go slow in the sanding process so as not to sand the keyframe too much, producing more high places. On a badly warped keyframe, one might have to cut out strips on the top of the frame and hammer in hardwood wedges in order to straighten it out (front or back rail only).

Bedding the balance rail can be done by either of two methods. The short method is to take a straightedge over the entire length of the keyframe, spanning the front and back rails over where a stud exists. Turn the stud down until it just touches the straightedge. At this point, the three rails are in a straight line. Do this to every stud, and if the keybed is perfectly flat (which it isn’t) then the keyframe should fit. But since the keybed is not perfect, correct any small differences by installing the keyframe complete with keys and stack into the piano, securing the cheekblocks. Now by lifting gently on the top of the stud, and at the same time knocking lightly with the other hand, adjust the stud so that it makes a knocking noise when the stud is lifted, but is secure with no pressure on the stud. Do this to all of the studs and the keyframe can be considered bedded to the keybed. The other method is with using strips of newspaper. With the keys off the keyframe but with the stack screwed on and cheekblocks secured, slide a strip of newspaper under each of the bedding screws and starting at one end, turn the studs down until friction is felt when the newspaper is pulled gently. Go onto the next stud and turn it down also until resistance is felt. Recheck the first and second studs before going on to the third. Continue the operation remembering to recheck those studs already set until all of the studs are down. Check the front rail to make sure that the studs are not down so far as to raise the front rail and you are finished.

5) ALIGN ACTION RAIL DISTANCE IF NEEDED

 

All piano actions were designed with a specific distance between the middle of the centre pin of the hammer shank to the middle of the center pin on the whippen flange. Most actions have an adjustment on one of the other rail to correct this measurement. Some, like Steinway, are permanently set. However, if this distance is not correct, the action will not play right and is impossible to fine regulate. Contact the manufacturer for the correct specifications for the particular instrument if this appears to be the case.

 

6) REMOVE THE STACK, POLISH KEY PINS, CLEAN KEYFRAME

 

Take the stack back off the keyframe and set it aside. If the punchings and backrail cloth are in good shape, clean with a brush. If not, replace with new felt and cardboard. Clean the key pins or replace if they are pitted. Turn the front rail pins back straight if they were turned before.

 

7) PUT KEYS BACK ON KEYFRAME, CHECK CENTER HOLE FOR LOOSE/TIGHT FIT

 

Return the keys back on the keyframe in the same manner in which they were removed, taking care not to ...

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Grand Regulation - - A Checklist - Part 2

Last week we talked about a 50-point checklist and knowing what changes are taking place during action regulation. A three-question quiz was also given which will be repeated here:

1) Does regulating the jack height to the balancier affect the strength of the repetition spring? 

2) Does regulating the let-off affect the backcheck distance? 

3) Which of the following affect the amount of aftertouch: key height, blow, jack alignment, jack height, let-off, drop, backcheck, repetition spring?

Now that a month has passed to think about the answers, wouldn’t it be great if there were some place to turn to look up the correct answers? How many of us have taken the time to thoroughly investigate and think out what happens in grand action regulating? Everyone should own or have access to a grand action model. These are a great help in trying to figure out a problem or to understand the hows and whys of the working parts.

Here is a grand regulation chart which lists the nine action regulation steps and how they directly affect each other. (You can find the chart at the bottom of my last post. It’s the 2nd graphic.) X’s mark steps which are affected, O’s mark those which are not.

 

It should now be quite easy to find the answers to the quiz. The answer to question no 1 is yes. Think of the butterfly type repetition spring as now used in Bosendorfer, Steinway, and Yamaha grands. As the balancier is raised or lowered to the correct height above the top of the jack, the tension on the repetition spring is changed. Think of the balancier and whippen as opening and closing like a jaw. The tension on the spring increases as the balancier is lowered. However, the effect this style of spring has is the opposite one would expect. Even though the tension increases, the hook of the spring moves forward (toward the keyboard) in the spring slot on the bottom of the balancier. This necessitates the spring tension to be increased in order to achieve the same effect, since the point of contact is now further from the balancier’s flange.

In answer to question no 2, the grand regulation chart is marked no. Now it is possible to argue that if the key is depressed slow enough, as when we regulate the let-off, and if the let-off is changed considerably, that the hammer will check at a different height. True, but the main factor here is not the let-off distance. Rather, the speed at which the key is depressed. In actual playing, the hammer must continue to move upwards after let-off in order to strike the string, then it falls back, going into check Changing the let-off only changes the amount of power that the key gives the hammer. The backcheck distance does change, of course, on whether the player gives the key a hard or soft blow. On a hard blow, the hammer rebounds more forcefully into the check position and ends up a little lower. On a very light blow, the hammer may not even go into check. Anyway, we can be pretty safe if the backchecks are regulated before the let-off, since as can be seen on the grand regulation chart, the backchecks only affect the repetition spring strength.

For the third question, the factors which affect aftertouch are:

1) Key height. Changing the key at the balance rail affects the key at the front rail by a factor of about 1:2. Adding a 0.010 balance rail punching will increase the dip, and hence the aftertouch, by about 0.020.

2) Blow. Piano actions are designed so that the dip to blow ratio is about 1:5. Changing the blow changes the amount of key dip needed for total escapement. When we raise the capstan to lessen the blow distance, the effect of raising the whippen puts the jack tender closer to the letoff button and the end of the balancier closer to the drop screw. This causes escapement to happen sooner in the stroke of the key, giving more aftertouch.

 

3) Jack alignment to the knuckle. Since the jack has a double function of raising the hammer and also causing let-off, regulating the jack to the knuckle changes when the jack tender engages the button. Therefore, if the jack is moved inward, toward the keys, the tender moves down and away from the let-off button, creating escapement later in the dip, meaning less aftertouch.

 

4) Let-off.From what has already been said, it is obvious that let-off directly influences aftertouch. Making the let-off closer to the string creates less aftertouch.

5) Drop.If drop is defined as the amount that the hammer drops after let-off, and that aftertouch is defined as the downward movement of the key after drop, then the amount of drop is proportionate to the amount of aftertouch. Decreasing the amount of drop increases the amount of aftertouch.

Notice that on the grand regulation chart ... 

 

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