Group 1 2012 Gate 2

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This section deals with the documentation of the dissection of our piano as planned in Gate 1. This plan laid out the ground work for the piano dissection, but in practice it required more problem solving and planning as we took on each step as a group. This included what we were going to do with the individual parts as we removed them from the piano in a way that would insure that the pieces were kept intact as well as have some sort of organization. Beyond dissection, we will analyze the interactions between parts and subsystems.

Contents

Project Management

Possible Corrective Action

On the whole, our work and management plans have proven to be at least moderately successful:

  • The dissection of the piano that was completed in almost the amount of time we allotted.
  • We have continued progress update meetings after every MAE 277 lecture.
  • The often resulting group meetings have done a good job of keeping us relatively on track to meet our self-imposed and actual deadlines.

One of our biggest problems is still attendance. Meeting directly after MAE 277 ensures timely meeting attendance, but our main meeting for this gate was on a weekend, and several group members showed up somewhat late or not at all. The absence of the group member during the actual piano dissection has proved very problematic, as they have less insight into the workings of the piano and very little knowledge of the steps we took to dissect it, which impacts their ability to contribute to the write-up of Gate 2. We will continue to stress the importance of attendance. To prevent missed meetings, we will contact group members shortly before meetings to verify their attendance.

We did avoid the problem of late work, though, by meeting after lectures to monitor progress. Due to scheduling issues, our planned dissection was planed closer to the deadline than desirable. However, the contant progress updates kept the group on track so that only a format check and proofread were needed to finalize the gate before the due date.

Our other most pressing problem is our inability to effectively work on important sections of the wiki pages simultaneously. We discovered during gate one that there is the possibility of accidentally overwriting work done by other gate members working on the same section if one saves after they do. To date, we have attempted to avoid this by having everyone work on different sections, and also having them prepare their sections in external word processors, but it became somewhat complicated to coordinate and took significantly longer to update key sections of Gate 2. In the future, we will most likely stress the use of word processors instead of the actual wiki pages.

Product Dissection

As a general rule, no part of the piano is truly meant to be taken apart by a consumer. The top hatch lifts up to expose parts of the action, and the bottom baseboard can be removed fairly easily without tools, but other than that, everything requires the use of a screwdriver to remove. That said, a screwdriver is really the only tool actually needed to take the entire piano apart. Almost all of the piano, save for those structural sections which are laminated together, is held together by screws. This results in the physical difficulty of each step being both highly similar and remarkably low. This causes the main difficulties of every step to be caused more by required delicacy of handling of parts and the amount of thought that is involved in deciding which part to take apart and how to get at them.

Difficulty Scale

The following is the difficulty scale we will use to describe the difficulty of each step outlined in the deconstruction in the piano. To allow for flexibility in actions taken in the steps, difficulty ratings will be given for each separate column, and then added together for a total difficulty rating. For instance, a step that requires one person to spend twenty minutes and has a moderate logic component would be denoted as "1-3-2" and "6" in the overall difficulty column. Steps with equivalent overall difficulties are roughly equivalent in difficulty in real life.

Scale # \'\'\'Number of People Required\'\'\' \'\'\'Time Taken\'\'\' \'\'\'Conceptual Difficulty\'\'\'
1 One Person <5 minutes Readily Apparent
2 Two Persons 5 to 15 minutes Some Investigation Required
3 Three Persons 15 to 30 minutes In-depth Investigation of Parts and/or Planning Required

Tools

  • Flat Head Screwdriver:
Most of the components of the piano were held together with basic flat head screws of various sizes. The flat head screwdriver was used for all of these components, and they were all directly reachable at their respective points in the dissection.
  • Pliers:
Some of the components were simply held together by compression in slots or with pegs. To remove these parts we used the pliers to ensure precision and safety of the fragile parts.
  • Wrench:
The only component that required the use of a wrench was the dissection of the pedals.

Steps

Piano with baseboard removed.
Piano after step five.
Piano after step seven.
Piano after step eight.
Piano after step nine.
\'\'\'#\'\'\' \'\'\'Step Description\'\'\' \'\'\'Tool Used\'\'\' \'\'\'Difficulty Rating\'\'\'
\'\'\'1\'\'\' Remove top hatch Screwdriver 4 2-1-1 2012 Group 1 Picture 3.jpeg
Lifting up the very top panel of the piano exposes parts of the action and two hinges held on with screws that secure the top of the panel. Remove them to allow for easier access to the rest of the piano.
\'\'\'2\'\'\' Remove bottom baseboard None 3 1-1-1 2012 Group 1 Picture 1.jpeg
There is a latch near the baseboard of the piano on the underside of the keys that holds the baseboard of the piano in. Flip it, and remove the baseboard.
\'\'\'3\'\'\' Remove horizontal bar on top of sliding keyboard cover Screwdriver 3 1-1-1 2012 Group 1 Picture 4.jpeg
Now that the the top hatch and base board are removed, remove the horizontal bar that the top hatch rested on. The bar is held up with two screws on each side, so a screwdriver was used for the disassembly.
\'\'\'4\'\'\' Remove keyboard cover Screwdriver 4 2-1-1 2012 Group 1 Picture 5.jpeg
The keyboard cover was attached to a hinge that allowed it to slide over the keys. Remove the screws holding it in to the side of the piano and lift out.
\'\'\'5\'\'\' Remove Horizontal bar on top of keys Screwdriver 3 1-1-1 2012 Group 1 Picture 6.jpeg
This bar holds the keys in place, and must be taken off next. It was held in by evenly spaced screws along its length.
\'\'\'6\'\'\' Remove steel pull-rods from key-levers None 6 2-2-2 2012 Group 1 Picture 9cropped.jpeg
Upon initial inspection, it appears that the action can be removed at this step. This is not the case. The action is connected to the keys by a series of long metal rods capped with dowels that will prevent movement unless they are disconnected. To remove, slightly depress the key and pull the dowel off the key towards the action. Note the bright orange felt underneath the removed pull-rods at right.
\'\'\'7\'\'\' Unscrew action bracket and lift out Screwdriver 5 3-1-1 2012 Group 1 Picture 8.jpeg
With the action disjoined from the keys, the only thing left holding it into the piano are screws on either side that attach to the piano body and screws to the back wall. These are unscrewed, and the action is carefully lifted out as to not disrupt the fragile members. Be sure to have at least one person holding up the unscrewed parts of the action.
\'\'\'8\'\'\' Remove keys and key pin board None 7 3-2-2 2012 Group 1 Picture 13.jpeg
All of the keys are only attached by vertical pins on the pull rod board. The keys are easily removed using our hands, and their numbers are inscribed in their body, so order was easily maintained. We took the extra step of storing the keys taped together in numerical order to facilitate reattaching them. 2012 Group 1 Picture 17.jpeg
\'\'\'9\'\'\' Remove key pin board None 4 2-1-1 2012 Group 1 Picture 23.jpeg
The board the keys were attached to was secured to the frame of the piano with screws placed along its length. Unscrew them.
\'\'\'10\'\'\' Detach pedal levers from pedals Wrench, pliers 3 1-1-1 2012 Group 1 Picture 20.jpeg
Release the pedal levers from pedals by unscrewing the threaded connector. These may be finger-tight or may require a wrench and pliers.
\'\'\'11\'\'\' Remove pedal dowels None 3 1-1-1 2012 Group 1 Picture 19.jpeg
The pedal dowels connect the pedal lever to the action. A simple vertical pin protruding from the bottom of the dowel is the only mounting hardware. With the action removed, the pedal dowels simply lift out of the pedal levers.
\'\'\'12\'\'\' Detach pedal levers from piano floor Screwdriver 3 1-1-1 2012 Group 1 Picture 38.jpeg
The pedal lever is attached to the piano floor by a flat spring. This spring is connected directly to the floor by two screws.
\'\'\'13\'\'\' Remove pedal hinges and remove axle from pedal Screwdriver 4 1-1-2 2012 Group 1 Picture 21.jpeg
The pivot for the pedal is screwed into the floor. The axles are press-fit into these and the pedal. Once the pivot block is loose, the axle pulls out.
\'\'\'14\'\'\' Unscrew pull-rod and associated lever Screwdriver 5 1-1-3 2012 Group 1 Picture 35.jpeg
With the action removed, the pull rod and the lever it activates can now be removed. It is joined to the action bracket with one screw and joined to the hammer by a cloth strap.
\'\'\'15\'\'\' Unscrew hammer and remove Screwdriver 5 1-1-3 2012 Group 1 Picture 37.jpeg
The hammer pivot is screwed to the action bracket with one screw. It is also joined to the pull-rod lever by a cloth strap. Once both the pull-rod lever and the hammer are loose, they can be removed from the action bracket.
\'\'\'16\'\'\' Unscrew mute Screwdriver 4 1-1-2 2012 Group 1 Picture 35.jpeg
The mute pivot is screwed to the action bracket by a single screw. After the screw is removed, take the mute off the action bracket.
\'\'\'17\'\'\' Unscrew the iron bracket on the end of the action Screwdriver 6 2-2-2 2012 Group 1 Picture 30.jpeg
The action’s structure is held together and attached to the piano body with cast iron brackets at its ends and center. This is also held on by screws that are removed with screwdrivers.
\'\'\'18\'\'\' Remove the una corda pedal bar None 5 2-1-2 2012 Group 1 Picture 30.jpeg
The una corda bar which runs behind the hammers pivots on the cast iron brackets in step 16. It is visible just above the bracket screws in the image at left. Once the brackets are loose, the una corda bar is free to drop from the action.
\'\'\'19\'\'\' Remove spring bar Screwdriver 6 2-1-3 2012 Group 1 Picture 29.jpeg
A bar with thin springs to return the hammers to rest position runs between the mutes and hammers. Remove the four screws that secure it and slide it out of the action.
\'\'\'20\'\'\' Unscrew the mutes above the hinges of the sustain pedal bar Screwdriver 7 1-3-3 2012 Group 1 Picture 32.jpeg
The metal sustain pedal bar runs behind all the mutes. Its hinges are also behind the mutes. To access the hinges of the sustain pedal bar, four mutes that cover the hinges\' screws must be removed. Unscrew as in step 15.
\'\'\'21\'\'\' Unscrew the hinges of the sustain pedal bar Screwdriver 3 1-1-1 2012 Group 1 Picture 33.jpeg
These hinges are held by screws to the action bracket. Remove the screws and slide the hinges off the axles on the sustain pedal bar.
\'\'\'22\'\'\' Pull sustain pedal bar out None 3 1-1-1 2012 Group 1 Picture 36.jpeg
The sustain pedal bar runs under the mutes. After the hinges are removed, the sustain pedal bar simply slides out from under the mutes.

Subsystems

Subsystem Flow Model

Subsystem List

Action Internal Subsystem

Hammer, mute, and action subsystem interaction
Piano-action.gif

The action as a whole contains the hammers and mutes, but within the action, there is a separate subsystem that takes input from the keys and pedals and operates the hammers and mutes. It consists of a pull-rod connected to the keys, a lever to operate the mute and a push rod that operates the hammer. To the right is an animated gif of the action-hammer-mute subsystem working. The hand is pulling the rod typically attached to the keys(See figure on right.).

Keys

The keys are the most easily accessible levers on the piano and serve as the primary input. They have no axle or spring; instead, they rest on a point on the bottom of the key and fall into place by weight balance. They transmit work done by the player\'s fingers through levers to kinetic energy within each subsystem in the action. This kinetic energy moves mutes and brings the hammers up to a high speed.

Hammers

The hammers are felt-covered wood levers that transmit kinetic energy through a physical striking movement into oscillations in the strings. They have light springs to return them to rest position.

Mutes

The mutes are felt pads that press against the strings to dampen sound. They are on steel levers and use strong springs. Mutes for the lowest notes have two felt pads that are closely formed to match the thicker strings. The mid-upper notes have flatter pads. The highest notes do not have mutes because their sound dies out quickly without a mute.

Sustain Pedal

The right pedal operates a metal bar that raises all the mutes off the strings simultaneously. A wood lever along the bottom of the piano on a spring operates the push-rod to transmit motion to the metal bar. The metal bar also has a spring to return it to rest position.

Una Corda Pedal

The left pedal operates a wood bar behind all the hammers. It physically moves them closer to the strings so they can\'t gather as much kinetic energy in their swing. The resulting sound is more quiet. The wood lever across the bottom of the piano is on a spring. The wood bar moves under the influence of gravity.

Strings and Cast-Iron Frame

The strings and cast-iron frame are on the back of the piano. The strings are meant to resonate at a frequency based on their length and mass. The lower notes are thicker and therefore heavier due to a wrapping of thicker wire around a basic steel wire. The cast iron frame supports the tension in all the strings.

Support Frame and Case

The piano\'s action and strings are housed in a wood case. The case has a top that can be propped open to allow more sound to propagate through the surrounding air. The back face of the case is made of a thinner wood with stiffening ribs. This so-called soundboard is directly attached to the cast-iron frame and strings and it allows the vibrations in the strings to produce sound outside the piano.

The front of the case supports the keyboard so it has upright posts to brace the keyboard against force from the player\'s hands. It also contains a fold-out cover to prevent accidental damage to the keys.

The entire case rests on four wheels to ease movement of the piano.

Subsystem Interactions

The action subsystem is a main hub of system input and output. It receives input signals and energy from the keys and pedals and outputs energy and signals to the strings and cast-iron frame.

All interactions operate over a physical connection through levers or push-rods. While these connections transmit signals to different subsystems, they may also transmit energy, for example, in the key to action to hammer connections.

Primary Input Interaction

The primary inputs of the piano are the keys and pedals. The keys send discrete signals based on which key is pressed and analog signals based on the relative force with which the key is struck. The pedals send binary signals. The signal medium is a physical lever.

The input signal from the keyboard to the action subsystem is in the form of material and energy. Which key is pressed determines which individual pitch section of the action is activated and the energy input to the key determines the output energy. The action sends the signals and energy to the hammers and mutes by striking the hammer and lifting the mute off the string for the note corresponding to that key. Once the key is released, the action subsystem instantly dampens the sound with the mute and allows the hammer to fall back to rest position.

The sustain pedal operates across all mutes in the action. It lifts all mutes off the keys to let any note to continue sounding after the player releases the key. It effectively bypasses the signal to the mutes from the action.

The una corda pedal operates across all hammers. It moves the hammers closer to the strings to prevent them from accumulating as much kinetic energy through their swing as they do without the pedal.

Final Output Interaction

The strings, cast-iron frame, and case all serve as part of the final output. The output is entirely sound energy. The inputs are analog signal and energy from the hammers and binary signal input from the mutes.

Which hammers have been activated and the energy associated with their inputs determines the pitch and volume of the sound output. The mutes determine how long the note continues to sound.

Subsystem Layout

The keyboards and pedals are oriented to allow an ergonomic playing position. The action subsystem is positioned centrally between the keys, hammers, and mutes so that it can receive direct inputs and send outputs to those systems. It is also oriented linearly across all the notes to provide equal signals to all note outputs. The pedal push-rods run up the side of the piano and operate bars across all the notes. That way, they don\'t interfere with the action subsystem by running up the middle, yet it can still modify signals to all the notes.

Global, Societal, Economic, and Environmental Factors

=Societal

The compact layout of subsystems allows for a smaller overall footprint of the piano. It can therefore be used in a home or studio where space is limited at the cost of a slightly lower acoustic performance.

Economic

An upright piano is much more cost effective than a grand piano, in that it is smaller and requires less material to manufacture, with the cost of a lesser acoustic performance. The inner workings of the action are constructed almost completely from wood, which creates a fairly durable design, but is much less costly than any form of metal or plastic. Wood is limited in shape, though. The directional strength with the grain lends itself to linear-shaped components that govern subsystem shape and even product shape.

Environmental

During dissection, we noticed large quantities of dust and small objects like coins accumulated in the piano. Subsystems need to operate in an environment that contains dust and possibly moisture with little maintenance. The keyboard, for example, is located so that dust and debris can fall between the keys into the case without jamming keys.

Citations

All knowledge in this section of the report was obtained from our elementary and/or background knowledge of pianos, physics, and this pdf: http://www.ptg.org/userfiles/file/learningCenter/How_A_Piano_Works.pdf