The 12 Stages of Upright Piano Making

 UK Piano page logo UK Piano Page

Design and construction of the piano.

The preparation of plans of every detail of design.
Making the structure to which the sound board, wrest-plank, iron frame, and the ends of the case work.
Making and fitting the sound board.
Positioning the four hundred and forty pins on the bridges controlling the speaking length of the strings.
Attaching the two hundred-and twenty strings at an average tension of 170 lbs.
Preparing and veneering the case parts.
Assembly of case work.
Positioning the action, keys and pedals.
Adjusting the mechanism of the action and keys to give correct reproduction and touch.
Mouldings, casters, music desk and other small fittings.
Gradually pulling the strings up to pitch and repeating the process till they stand in tune.
The hammer heads by shaping and modifying the resilience of the felt to get an even response to all the notes.


Preparing the full sized plans showing every detail of design
  • (A) The "strike line" is drawn across a sheet of pre-shrunk paper, about three quarters of the way up from the bottom, this is the datum line from which all string lengths and other calculations are made.
  • (B ) Factors to be considered when drawing "scale" length , the top note and all descending notes. The number of breaks and parts of which wire gauges changes angle of strings, number of tricords, bicords and mono cords. These factors all influence the height and length of the piano, the design of the case action and keys.
  • (C) Pattern-making. This is part of scale making and involves making wooden patterns of the iron frame and other parts.

Basic facts about piano backs, "a super or extended compass as seven and a quarter octaves e.g. 88 notes. The 88 notes are made up of an average of 220 strings, the average string tension is about 170 lbs per string, with an increase of 15% in the bass, between the top and the centre of the compass the string lengths in octaves is increased in the ratio of 17:9 for each descending octaves, wire gauges increase by a half every six notes, down to the tenor area and more frequently there after. Particular consideration is made for string lengths to increase all the string lengths at a ratio of 17:9 especially in the bass it would be very impractical so the diameters of the bass stings are increased with nearly every note in the bass.


Making a the wooden structure to which the sound board, wrest-plank, iron frame, and ends of the case are fixed. Almost any cheap wood is used and a id under "deal" The back is made of about three and five brasings spaced and held together by wooden blocks. The wrest-plank is glued to the top, front of the brasings is made of beech wood. And it is made of a laminated construction of between two and eighteen layers; the grain of each layer running in different directions to the layers of either side this helps the plank to resist splitting and assists pin grip.


Making and fitting the sound board also idd the belly this is made of European or Canadian sprus or pine. Cut in to boards about 3/8 inches thick and 5-6 inches wide. The boards are BUTTED and glued edge to edge, so that the grain of the finish belly is running from top right to bottom left. "ribs" or sound board bars are glued to the back of the sound board for three main reasons.
(A) To strengthen the sound board.
(B) To help maintain the ",crown"
(C) To spread the sound waves ACROSS the grain of the sound board. Ribs are made of similar timber to the sound board and are thin at the end to allow the sound board to be flexible the uncarved sound board bridges "made of laminated beech) is glued to the sound boards as near as possible to the crown. Before the sound board is varnished, bridges are sometimes screwed from the back of the sound board

Ribs are glued to the back of the sound board for three reasons,
(A) To strengthen the sound board.
{B) to help maintain the CROWN
(C) to spread the sound waves ACROSS the grain of the sound board.
The ribs are made of similar timber to the sound board and are thinned at the ends. To allow the sound board to be flexible the uncarved sound board bridges - made of laminated beech - is glued to the sound board as near as possible to the nearest point to the CROWN before the sound board is varnished. Bridges are sometimes screwed from the back of the sound board.

Sound boards are curved in similar fashion to roads e.g. the highest point being in the middle this is to assist good contact between strings and bridges and to withstand the "DOWN BARING" of the strings. In some factories the CROWN is created by the sound board being pressed down into a hollowed out bed for several hours. Whilst in other factories it is produced by the sound board being projected to heat and moister and dried, so that its shape is distorted to produce the CROWN. On the sound board receives several coats of varnish to protect it from humidity changes and to assist in sound wave transmission. THE SOUND BOARD IS THE PIANOS AMPLIFIER.


Positioning the average 440 pins to the sound board bridges their functions being:
(A) Determining the strings speaking length.
(B) To keep the strings evenly spaced.
(C) To ensure a good contact between strings and bridges by the introduction of "side draft".

Side draft: as the strings pass by the bridge pins they are directed at an angle which causes them to divert from a straight line between the wrest pins and the hitch pins. Bridge pins are made of MILD STEEL and are driven into beech wood bridge at appropriate angles. The marker off will usually carve away the edge of the bridge above and below each row of pins so as to allow clearance of strings., The belly bridge is the pianos transmitter as it transmits vibrations from the string to the belly


With the back horizontal the cast iron frame is bolted in to position the modern frames is n known as "full" or "all-over which means, it covers to wrest plank. Bushing the iron frames the wrest pins holes are lined with small beech wood dowels to support the pins and stop them from coming in to contact with the iron frame. After the bushings are tapped in to place and electric drill is passed through them and in to the wrest plank to accommodate the wrest pins, These holes are drilled at an appropriate angle to resist the down pull of the-strings.


Attaching the average 220 strings the average tension. of each string is 170 lbs increase by 15% in the bass. They are mainly made of either stainless, plated, or polished wire the covered strings have a wire core which is covered with one or more layers of copper. Stirging is done with the back horizontal and with no pressure bar on it starts from the treble, wire gauges change about every six notes in the upper compass and more frequently lower down. The pressure bar and the listing are added as parts of stringing


Making and where necessary veneering the case parts various types of whitewood are used for case parts, agba, and limba, come from Africa being popular at the moment. Chipboard, is also used. Case parts are cut out in the milll, The wood used in piano parts retains a small percentage of its original moister content in order to make it durable, most of the case parts are veneered, which give the completed case the appearance of being made of one solid piece of ac attractive wood. A piano with a case made of a combination of woods will thaw for trim out logging as made in one piece of solid wood of, walnut, oak, maple, mahogany etc. veneers are put on with heat adhesives under pressure.


Assembling the case work round the piano this is really a cabinet making skill involving gluing, screwing, and doweling and the use of clamps and presses


Positioning of the actions keys, and pedals. At this stage there has not been any damper heads or hammer heads or shanks, the action finishes schedule is as follows:-
(a) Fit by means of screwing the action to the pianos action cup, block, securing stages
(b Line up the damper wires and the drums with the strings and set the drums at the correct angle; then glue on the damper heads, using the pressure of the strings clip to keep them in to position.
(c) Starting from the top all the shanks are cut to the appropriate lengths, so the hammers strike the parts of the string which is designated to them in "scale drawings" the hammers and the shanks are glued in to position.
(d) The key frame and the keys are now positioned over the action. so that the capstan are under the heads of the whipins.
(e) The trap work (pedel mechanism) is added.


Adjusting the mechanism of the action and keys to get the correct reproduction and touch operations carried out as follows:-
{a} Adjustment of tape lengths.
(b) Setting the blow to the correct distance between the strings and the nose of the hammers. This is followed by the correct positioning of the hammer wrest rail and adjustment of the capstans to centre the blow is correct and there is no lost motion in the key this capstan regulating is called "Making up the lost touch" or "Taking out the lost motion"
{c} Regulating the touch depth
(d) Checking off and depth touch these are done simultaneously because of the close relationship.
(e) lining up of the dampers and the damper lift.
(f) Regulation of the trap work
(g Spacing and easing of the keys.


Adding mouldings, music desks, locks, backing, handles, and other various small fittings. Sometimes the fly finisher fits the trap work if it is not done by the action finisher.


Gradually pulling the strings up to pitch and getting them to stand in tune. This really starts immediately after the back is strung and without the aid of keys and action a typical tuning process:-
(a) strain and rub down; chipping the back in " semitones and rubbing the strings with a wheel or other device.
(b) First chip, second chip, and third chip, all progressively getting finer.
(c) Two or three rough tunings, each one progressively finer than the other one.
(d) Fine Tuning. The latter stages are carried out with the action in.


Voicing the hammer heads by shaping and remodelling the resilience of the felt to get an even response on all notes.. The hammers are shaped where necessary with a fine glass paper on a flat stick or shaped blocked. The texture or the resilience of the felt is altered by injecting it with up to four fine steal needles. Toning requires great skill of ears and heads and it cannot be carried out until the piano is fine tuned.

* NOTE:Piano cast iron frames are made at an foundry away from the factory the molten metal is poured in to a mould. Cast iron will withstand enormous stress, but cracks easily if subjected to a sharp jult or rapid and extreme changes in temperature. In the early state iron frames or grey but are usually finished in gold laquer

Covered string are often made in factories away from the piano factory they have a steal core covered with copper. The copper covering is used to increase the strings density.

©2000 Barrie Heaton

Visit my website Piano Tuning in Lancashire.