Simplifying Complex Systems

Transcription

1 Simplifying Complex Systems The beginnings of complex woodwind mechanisms Complex Systems as standard features on Heckel System Bassoons Contending with the complexity Adjusting the Whisper Key System Adjusting the High G Ring Key Adjusting the F' to G' Trill Mechanism Adjusting the C' to D' Trill Mechanism Illustrations: Bassoon Key Identification Whisper Key System High G Ring Key F'/G' Trill Key C'-D' Trill Key The beginnings of complex woodwind mechanisms Complex key mechanisms on woodwind instruments didn t really develop until the beginning of the 19 th century. Prior to that keywork was almost totally restricted to cross hinged levers. Longitudinal hinge axes were not yet practical. It wasn t until a very specific piece of hardware came into existence that keywork was liberated from that restriction. The first appearance of the hinge post, or pillar, was in 1806 on flutes made by Claude Laurent of Paris. The initial objective was to create ring keys on flutes. The post is quite possibly the single most significant invention essential to modern woodwind keywork. Posts soon enabled the development of complex mechanisms that integrated components together in ways that would not have previously been conceivable. Complex Systems as standard features on Heckel System Bassoons In their most basic form modern Heckel system bassoons from all makers include four systems that integrate otherwise separate mechanisms together. Other integrated systems occur on bassoons, but would normally not be found on every bassoon. The whisper key is the most basic of these complex systems. It s also the most easily overlooked, despite being directly in front of the eye of the player and being the very first key a beginning player is taught to use. It deserves special mention because it is the only register vent key among woodwinds that is open standing. That minor detail has created problems requiring complex solutions. The bocal vent needs to be open for only a few notes, but that means it must be held closed for all the other notes. Therein lays the origin of its complexity. In its most common form it involves four separate keys. Two parts are obvious: the touch key operated by the left thumb and the pad key which closes the vent hole on the bocal. The first problems appear when the player needs to use his left thumb to play the lowest notes on the instrument. The need to liberate the player s left thumb from the whisper key touch demanded another method of closing the bocal vent for low notes. Page 1 of 11

2 To liberate the player s left thumb while continuing to keep the bocal vent closed the low E key was modified to automatically hold the bocal vent closed whenever pitches below low F are played. The low E key is connected by a bridge key on the wing joint to the touch and pad keys of the whisper key system. That s the basic whisper key system. The basic system isn t always sufficient. The next steps add locks in various formats for either thumb that hold the bocal vent closed. A bridge linkage enables the high A key to close the whisper key to achieve better sound and pitch for that note. Enhanced flexibility for the player s fingerings can be achieved by adding additional whisper keys for the player s left little finger or right thumb. Clearly, it has become a complex system and all because the pad status is backwards. The simplest complex mechanism is the F' to G' trill key, often called the F' rocker. This mechanism enables the trill by using the thumb F' key to hold the low F key closed allowing the player s left little finger to depress the little finger G' key without being encumbered by depressing the low F key. The mechanism comprises one small rocker key that pushes a pin through the center of the boot joint to close the low F key. Simple on its own, but added complexity comes from the low F key being integrated into the next system on the list. The next two mechanisms involve reverse sprung mechanisms. These are sophisticated mechanisms in which a normally closed pad key is sprung to open. A primary control key is strongly sprung to hold the pad key closed. Depressing that control key allows the pad key to open. Closing the key below will close the pad. The G' key on saxophones is a good example of a reverse sprung mechanism. The strongly sprung G' spatula holds the pad closed until the G' spatula is depressed allowing the pad to open. While the spatula remains depressed another key below the pad can close the pad. Some reverse sprung mechanisms can become very sophisticated in what they can do for the performer. Their complexity usually relegates them to options not normally included in standard keywork specifications. The third complex mechanism on a bassoon is the self acting high G ring key. This is a reverse sprung system, unique in its simplicity. The pad on this key closes the high G vent hole. The primary control is provided by the low F key. When the low F key is depressed by the player s right little finger the high G ring key is allowed to open. The secondary control of this key is the ring under the player s right middle finger. The fingering combinations of the little finger and the middle finger are such that the high G ring opens to play the high G. On its own the high G ring key is simple. It becomes more complicated when you remember that the low F key is also integrated with the F' to G' trill key. Both of these systems must be coordinated with each other. The most complex of these systems is the C' to D' trill key mechanism. This reverse sprung mechanism directly includes three keys, which in turn involve two other keys that are part of a group of four or five keys that must be coordinated together as a set, and which must also be coordinated with another set of four keys on another joint. Failure to work with all of these keys in the correct sequence is a common reason for the adjustment of the left thumb keys of the bassoon to become difficult. Contending with the complexity There is a natural tendency to look at a complex system in its totality. Looking at too much at once is the source of difficulties. This is commonly seen when a repair student is faced with a complex system. It is immediately overwhelming. The solution of the problem is to learn to not look at the totality, but rather to look at individual components. When teaching someone how to work with such systems the first rule must be: One thing at a time! This concept is very similar to the KISS system, which is an Page 2 of 11

3 acronym for: Keep It Simple, Stupid. Both describe the idea of ignoring the unimportant. Anything other than the one thing you re working on is a distraction. With that in mind, make sure that each single part is correctly functioning. Don t worry about how it relates to another key, yet. Just worry about that one key. Adding components together comes later. The next step comes into play after each individual part of a multiple component system works correctly. Now add the second linked part to the first. Remember that each of these parts has already been made to function individually. Now they must function correctly together. Continue with this idea so that all of the components work together. Systems of only two components will probably be completed at this point. Systems with more components may require revision of the prior adjustments. Experience will enable a repairer to know the correct sequences in which to assemble the components. There s usually a best sequence that minimizes the potential for possible revisions. Adjusting the Whisper Key System: The most common complaints about whisper keys is that the pad doesn t close or that it closes too soon and prevents the low E key from closing properly. The normal reaction by a repairer is to adjust the pad key. That s often not where the problem needs to be fixed. Starting conditions: a) The low E key needs to be padded and set to the correct pad opening. This needs to be done before you start on the whisper key. The whisper key system is typically the last key added, so this condition will be normal. If the low E key is not correct everything else you do on the whisper key may need to be corrected later. b) The whisper key spatula should be in place and aligned with the other thumb key touches. c) Each of the hinges should be adjusted to remove any lateral movement from the key. Longitudinal movement should also be minimized at the same time. Always begin adjusting the whisper key system from the bottom end the low E key. That s the rule for whisper keys: work from bottom to top. Step 1: Any error in assembling the wing joint to the boot joint will mess up the whisper key system. A sloppy fit of the wing tenon in the boot socket can guarantee failure. Do whatever is needed to get the tenon to properly and securely fit the socket. There are often alignment marks on the boot and wing joints that can help in assembling these two joints correctly. Step 2: Install and adjust the whisper key pad. This can be done at the beginning or end of the process, but it s easy to do it first. This is not a pad that is seated on a tone hole facing. Just get it level and centered in the pad cup. Adjusting it to the bocal vent comes later. Use a BASSOON pad! A common problem with whisper keys is that the pad in the wrong thickness. You won t succeed if the pad is too thick or too thin. Saxophone pads are too thick and will not work! Synthetic pads for clarinets can be too thin and skin pads will rip too easily. Use a BASSOON pad! It is important to note that the correct position for the bocal is not perpendicular to the plane of the body. Rather, it is placed slightly to the east, roughly over the high A vent hole. Sometimes, it will appear that the pad thickness is correct, but the pad is not centered over the vent button. There is an adjustment that enables the pad to be moved to center it. It is done by rotating the offset extension rod that extends the pad cup above the end of the joint. The pad arm is rotated relative to the offset arms. This causes the pad cup to traverse laterally across the vent button. Set the pad key aside. It will be in your way until other adjustments are made. Page 3 of 11

4 Step 3: Adjust the connections from the boot. Having the boot, wing, and bass joints all assembled while you work on the whisper key system can make things easier. Have the spatula key, the bridge key, and the low E key in place. The low E key needs to be padded and adjusted for the correct pad opening. The upper arm of the bridge key needs to connect the arm from the spatula key squarely, so there is only the desired action and no rocking. Step 4a: If there is no right hand whisper key lock present, adjust the bridge key so that both ends rest on their connecting keys. Do this with the low E key open. There shouldn t be any lateral play at either end of the bridge key. The lateral position of the bridge arm on the upper arm of the low E key affects the amount of rotation for the system. This can sometimes be used to adjust the whisper key pad closure. The bridge arm should contact the E key arm about half way between the hinges of the bridge key and the low E key. When it is closer to the low E key hinge the whisper key action will be reduced; when it is closer to the bridge key hinge the action will be increased. This adjustment is only usable in the absence of a right hand lock, as the lock will demand that the bridge arm be properly aligned with the lock. Step 4b: A right hand whisper key lock can make the adjustment of the bridge arm more complicated. The low E key arm needs to be coordinated with the lock. The lock dictates how high the bridge arm rises. The lock needs to lift the bridge arm very slightly higher than the low E key arm does. Achieving this may require adjusting the height of the low E key arm. While it is desirable to keep that upper arm of the low E key close to the body, without actually touching the body, a right hand whisper key lock may require that position to be higher. With the low E key arm adjusted to the bridge arm and the whisper key lock, adjust the bridge key to eliminate any free play at both ends of the key. This is done with the lock disengaged and the low E key open. The reason for having the lock lift the bridge arm higher than the low E key arm concerns player comfort. When closing the low E key with the lock engaged the player may interpret the first contact as indicating that the low E key pad is closed. Having the lock lift the bridge arm slightly higher can ensure that the first contact occurs when the low E key actually closes. Step 5: Install the pad key. Check the camelback for alignment errors. a) The underside should appear parallel with the surface of the wing. b) The length of the camelback should appear aligned with the long axis of the wing. c) At rest, the flat spring should lay flat on the upper arm of the bridge key. This can be difficult to correct, but usually involves raising or lowering the lower end of the camelback relative to the hinge axis. d) There should be a small amount of flex available to the flat spring. That flex exists to provide a small amount of desirable error in the adjustment. e) As the spatula lifts the pad key the edge of the flat spring must not dig into the surface of the upper bridge arm. f) The west side of the camelback must not hit the lower post of the two prong key. Step 6: Adjust the closure of the pad. With the wing properly aligned with the boot joint, the pad must close on the bocal vent without inhibiting the closure of the low E key. Usually, this requires twisting the length of the pad key hinge. If there is a high A bridge in the middle of the pad key, adjustments should be made as if the pad key was two separate keys. First, adjust between the camelback to the A bridge so that at rest both are in contact with their respective connections. Next adjust the A bridge to the pad so that the low E key closes the whisper key pad. Page 4 of 11

5 Left hand whisper key locks function without affecting the adjustments of the system. Make certain that the spring effectively holds the lock key in both the unlocked and locked positions. Any adjustment of the high A bridge will usually be in the connection between the high A key and the whisper key hinge. The rare little finger whisper key spatula, and the rarer right thumb whisper key spatula should not affect the essential functions and adjustments of the whisper key system. Adjusting the High G Ring Key Step 1: Begin by ignoring the ring key. Set it aside. This key depends on the low F key for its correct installation. Pad the low F key and get the two keys of the low F system working together. Don t worry about the pad height until later when the high G ring key is adjusted to the low F key. Remove the low F spatula and set it aside, as it will be in your way for padding the high G ring key. Step 2: Pad the ring key. Don t worry about the ring and lower arm of this key, yet. Just get the pad right. Reseating it later will mess with the other adjustments. The ring key tends to be one of the noisier keys on bassoons. Take some extra effort to fit the hinge to avoid lateral slop at the pivots. The use of synthetic pads is preferable to cork or leather pads for this key. Cork is too noisy and leather will eventually get sticky due to the oxidation that develops on the nickel silver vent liner. Pad thickness is critical to success for this key. The pad thickness must match the thickness for which the pad cup was mounted. A pad that is too thick or too thin will cause problems. The first suggestion that the pad thickness is wrong will be if the ring is obviously not level with the finger hole. Older bassoons may have a flat bottomed casting rather than an actual pad cup. These were intended to have pad quality cork glued directly to the casting. Select the closest match for the cork thickness; slightly too thick is preferable to too thin. Hint: it s possible to adjust the level of the casting before you glue the cork to it. With the cork glued in place, sand the face of the cork to seat the pad, so that the impression in the cork is equal all around. This is easiest done without the other keys in the way, as that allows the ring key to flip all the way over for easy access to the pad without removing the key. Any instrument with a pad cup of this type will be old enough that this key will have been readjusted many times and is probably messed up. Step 3: Adjust the ring key. Two alignments are important. 1) The ring must be aligned with the rim of the finger hole, and 2) the lower arm of the ring key and the connecting arm of the low F key MUST connect as a straight line between the two hinges. It is essential that these two conditions are correct. When adjusting the ring key it is important to always adjust between adjacent arms on the hinge. That is, adjust the pad to the ring, and adjust the ring to the lower arm. NEVER adjust the pad to the lower arm. With the pad closed, the ring key is correct when the ring is visually centered and level with the rim of the finger hole and feels comfortable under the finger. If the ring bangs on the tube some added clearance cut into the underside of the ring may be needed. With the low F key in place and the ring key pad closed, the lower arm of the ring key must align straight with the arm of the low F key. This is VERY IMPORTANT! This connection must not arch up or dip down, but must be straight between the two hinges. Ignore the body surface as the posts are different heights and the arms will not be parallel with the body. If the arms are high the low F touch will be Page 5 of 11

6 low, messing with its alignment with the little finger F' and G' touches and the pad closed by the low F key will be too low. If the arms are too low the touches will again be misaligned in the opposite way with potentially either the little finger F# touch or the pad cup lift arm on the low F spatula key preventing the ring key pad from closing. It can also mess up the adjustment of the F' to G' trill key on the other side of the boot joint. All of these adjustments depend on the thickness of the pad in the high G ring key. Anytime this pad is replaced each of these adjustments will need to be checked. Step 4: Set the pad opening for the low F key. This is done by adjusting the lift arm s height relative to the spatula. Expect some space between the lift arm and the body. It is desirable to set the pad opening before proceeding to the F' G' trill key. If you change the pad opening later the through pin length will need to be changed. The spring on the ring key must be sufficient to lift the key with certainty, but no more than necessary. The springs on the low F spatula and pad keys combined must be sufficient to hold the ring key closed. Depressing the low F key will allow the ring key to open; releasing the low F key will always close the ring key. Adjusting the F' to G' Trill Mechanism: The F to G' trill key, often called the F' rocker, is one of the easiest adjustments on the instrument. It s typically one of the last keys on the boot to install. The high G ring key and low F key system must be in place with the proper pad opening, and the thumb F' key should be padded and in place. When the F' key is depressed the rocker key pushes a pin through the boot to close the low F key. That pin must have a slight amount of free play at its ends. Without free play the high G ring key could leak. The free play doesn t need to be great, but it must be there. The primary method of adjustment is to shorten the through pin, or replace it with a longer pin. There is no universally perfect length for this or any other through pin. It s a matter of adjusting the pin length to be correct for each installation. There are always other ways to create problems. If the pin arm of the F' rocker touches the body of the boot the pin can t effectively close the low F key. Twist the hinge to raise the pin arm higher and use a longer pin. In general, with the other arm against the closed pad cup, the pin arm should be square with the pin or very slightly high. Pins must move freely through the pin hole. Dirty pins may not move freely. Warped pins may not move freely. Pin holes that have debris or other obstructions may prevent pins from moving freely. Pin holes can leak as badly as a leaky pad; don t hesitate to seal them. Adjusting the C' to D' Trill Mechanism: On its own, this mechanism follows the basic format of a normal reverse sprung mechanism. What makes it more complex is the substantial degree to which it affects and is affected by other keywork. Getting this mechanism set up correctly requires doing some things out of what might seem to be the logical order. Before the C' to D' trill mechanism can be correctly adjusted the thumb keys of the wing joint must be adjusted to their proper key height and alignment. The adjustment of those thumb keys on the wing depends on the thumb keys on the bass joint being set to their correct pad openings and key heights. Thus, the bass joint must be fully padded first, so that the thumb keys on the wing can be adjusted relative to the bass keys, and only after all of that is done can the C' to D' trill mechanism Page 6 of 11

7 be adjusted correctly. Any later changes to the key heights of the wing thumb keys may necessitate changing the adjustments of the C' D' trill mechanism. Step 1: Complete the bass joint taking care to adjust the pad openings and touch heights. Be sure that the pad opening for the low C key on the bass joint is correct. The other thumb keys on the bass depend on that pad opening. Step 2: Pad the thumb levers of the wing. Coordinate them and the whisper key touch with the bass joint keys. At this point you re only concerned with the static position of the wing key touches, not their depressions. The touch surfaces of the whisper key, C' and high A keys are all approximately on the same level with the bass joint keys; the touch surfaces of the high C and high D keys are slightly higher, so that they can be accessed past the low B and B( levers on the bass joint. The center lines of the C' lever and the high C key lever should be in line with each other creating a visually straight line from one end of the wing to the other. Check that the low B( touch and the high C and D touches are not in conflict with each other. Adjust their positions laterally if that occurs. The correct alignment of the wing and bass joints is important for this detail. Look for alignment marks to help align the wing and boot joints. For the bass rotation, don t depend on the wing stop block. Theoretically, the hinges of the C' key on the wing and the four or five hinges of the thumb keys on the bass joint should all be parallel. Check this by sighting from the boot down past the wing and bass joints With the positions of the thumb keys of the wing correctly positioned, the bass and boot joints can be set aside. Finally you can actually work on the C' to D' trill key mechanism. Note on key depressions: The amount of depression of the wing thumb keys is not critical. Acoustically, their pad openings require far less depression than is desirable for player comfort. Ignore the pad openings and focus on the touch depressions. A depression of 2mm or slightly more is good. It is important that all of the wing levers depress the same amount. To this end, make a small gauge of drill rod. The gauge is easiest to use if 5/8 at the end of it is bent at 90 degrees. A similar bend on the other end about three inches from the first makes the gauge easier to handle. At this time set the depression of the high A and high D keys by using the gauge to check that the gap under those keys to the stop posts is correct. Modify the stop posts and/or the corking thickness to get the depression correct. Ignore the depression under the C' and high C keys at this point. Remove the thumb keys from the wing. Question: Does this wing have a ring key or a plateau for the third finger hole? There are slightly different procedures for the two third finger touches. Step 3a Plateau: If the instrument has a plateau key pad it now. Don t worry about the pad opening yet. The spring should be bent toward the east, as it must lift the pad up. Remove the key and set it aside. Step 3b Ring: If the instrument has a ring key make sure that key moves easily and that the ring fits around the finger tube without hitting or rubbing against anything. The spring must be bent to the west to hold the ring down. Remove the key and set it aside. Page 7 of 11

8 Step 4: Pad the E( vent key. This is easiest when neither the ring or plateau key nor the C' lever is in the way. Check that the west side of the upper arm does not touch the body, as that would prevent the pad from closing. The two prong key should not be on the instrument yet. The spring of this key must open the pad without question, but don t overdo it. With a ring key it must also lift the ring up. Step 5a Plateau: Add the plateau key. The two pads must close simultaneously. Also, the plateau key must have a pad opening of approximately 3/32 (2.4mm). Adjust the two keys for simultaneous closure and cork the plateau key s foot for pad opening. If the plateau key needs to open more raise it up and then twist the hinge of the E( vent key to achieve both requirements. The spring must open the plateau key. Step 5b Ring: Add the ring key. Adjust the ring so that depressing it closes the pad with the ring level with the finger hole tube. Check that the ring does not hit the tone hole liner or bottom out in the counterfacing. It is of no importance if the ring key can rotate upward more than the E flat vent key requires of it, as the spring for the ring key holds the ring down. It is possible to have both ring and plateau keys that are interchangeable. The adjustment of the plateau key is more critical than that of the ring key, so get the plateau key correct first before adjusting the ring key. The biggest challenge for swapping between keys is reversing the bend of the spring. Step 6: Install the two prong key. The E( vent key will also be needed. The two prong key needs to have the silencing material on its lower connecting arm in place. Do not add cork under the prong(s) yet. Cork will be needed under only one prong, usually the upper prong under the high C key. The strong spring on this key will hold the E( vent pad closed. Step 7, the Flicking Gap: The performance technique of flicking requires gap of approximately 0.015" to between the jots under the touches of the C' and high C keys and the prongs of the two prong key beneath them. This allows the player to briefly open the key just enough to initiate playing the upper octave note, without actuating the C' D' trill mechanism. This gap can be measured by using a 6" steel scale which is typically 0.015" thick. Adjust the prongs of the two prong key so that that they each are square with the jots of the keys above them. Twist the hinge of the two prong key between the middle prong and lower link arm to provide the flicking gap. This procedure requires the E( vent key and the C' and high C keys in place, in addition to the two prong key. The high A key, high D key and the whisper key are not needed for this. Step 7: Estimate the necessary thickness of cork to be added under the upper prong of the two prong key. Place a piece of cork under the upper prong and depress either the high C or C' key to hold it in place. Use the 5mm gauge described in step 2 to check the gap under the other key. Anticipate that the cork will need some adjustment in thickness so opt for something slightly too thick. Glue it on, trim it and put the key back on, together with the C sharp and high C keys. Using the gauge hold one of the levers down and check the gap under the other lever. Repeat with the other lever. Correct the cork thickness under the two prong key until the gauge tells you that you have the cork thickness correct. All of the lever touches should now depress the same amount. When the C' or high C levers are depressed the E( vent key pad can open. Depressing the plateau/ring key will close the E( vent key pad. That should complete the task. Page 8 of 11

9 Page 9 of 11

10 Whisper Key System Page 10 of 11

11 C' to D' Trill Mechanism High G Ring Key & E F' Trill Key Page 11 of 11