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This is from a series of articles by W. H. Davies of Liverpool published in The English Mechanic and World of Science in July and August, 1878. The first part is here. They can mostly be downloaded from Google Books but part of part 6 is missing. The vertically strung English sticker action upright piano Mr. Davies describes was old fashioned at the time and many piano tuners won't service them now, and the services and patterns he offers as well as the parts he recommends are no longer available so some options might be researched when you follow his directions. I edited and broke it up a little, and reproduced some of the illustrations as vector drawings. The front illustration here is "Strengthening a sounding board using gobars" by W. H. Margetson, from Joseph Hatton's article "How Pianos are Made" in The English Illustrated Magazine 1891-1892.

The second part describes making and fitting the soundboard.

Step 1: Preparing the Back

HOW TO MAKE A PIANOFORTE

The next step will be the "bellying;" but, before describing this, I will premise that there are, as the reader is no doubt aware, many methods both of making and fixing the soundboard - the one selected, from its simplicity of structure and freedom from dangerous pressure being, in my opinion, the best adapted under the circumstances.

We will begin by preparing the back to receive it. As the linings are at present level with the bracings, they must be raised by means of hardwood slips to the proper height, the length of the bass slip being of the full depth of the soundboard, and of the same width as the lining; the thickness commencing from under the plank at 1/4in. graduates to 3/4in. at the middle, and down again to 5/8in. at the bottom; the treble slip being less than 9in. in length, the rounding can be dispensed with; it will suffice to slant in a straight line from 1/4in. at the top to 5/8in.,* where it joins the bent side; the wedges are now to be reduced so that a straight edge, when resting at each end of the slips, will just touch them.

{* best guess}

Step 2: Preparing the Soundboard Wood

The soundboard is usually made of Swiss pine; but as an amateur will probably find this hard to procure dry, I think it will be better to substitute the best quality 1/2in. American pine, being careful to select it dry, sound, and free from knots. The appearance of this may not be quite so clean as the Swiss, but in all other respects I think the two will be found equal; while, the boards being much wider, the number of joints will be less.

Before cutting into lengths (which run parallel to the wrest plank) it is safer to reject the first 6in. or so at the end, as this part is usually faulty.

Step 3: Joining the Planks and Thicknessing the Soundboard

Rubbing the joints will hardly be found practicable with such thin boards; it will, therefore, be better to spring them together. This is done by screwing two lengths of wood firmly down, leaving the space between about 1/4in less than the width of the soundboard. This, when placed with both sides touching, will of course be bowed in the middle, so that from a small downward an immense pressure is obtained, and all superfluous glue will be forced out. The soundboard will then be ready for planing to a thickness.

Hardly two opinions agree as to what this should be. Without pretending to decide so knotty a point, I think a uniform thickness of from 5/16 to 1/4 in. will be found as good as any, allowing it to be thicker, if anywhere, just above the plate, where it will be left without support.

Step 4: Fitting and Installing the Soundboard

It can then be fitted, allowing a space of 1/4in. all round the bent side and under the wrest plank.

While it is in position it will be better to tack temporary stops occasionally, or to screw the four corners so that it may be replaced exactly after each removal; but, before it is taken out, mark where the bracings come, and strike a middle line evenly between them for the traverse bars; these are of 3/4in. spruce, tapered to 3/4in.* at the outside edge, 1 1/2in. wide for eight bracings, and 1 3/4 in for six bracing backs, and extending fully across the soundboard at their respective positions. The jointed side is usually left about 1/4* higher in the middle than at the ends. They are chamfered 4in. from each end to 1/4in.* - see Fig. 2.

To glue them on will, I fear, be a difficult task, as the handscrew chops will not reach far enough. Putting screws though the front would pull the bar to a joint, but their weight would affect the vibration. In the trade it is customary to spring a lancewood bar between it and the ceiling; in this way all parts of the soundboard can be reached. Doubtless the ingenuity of the amateur will find a substitute, it being important that the joints should be close everywhere.

Step 5: The Bentside Slip

A "bent side slip" is next required to support the soundboard at that part between the bracings. This is cut to the curve of the bent side out of 3/4in. beech of similar width, and graduating in thickness from 1/2in. where it leaves the treble lining to 5/8in. under the plate, from which position to the bass lining the soundboard can be left free.

Step 6: Fitting Up the Iron Back

We will now turn our attention to the fitting up of an iron back. The frames are generally made for a 9in. wrest plank, but as about 7 1/2in. only of that is necessary for pinning, the 8in. plank can be widened by jointing it at the top with a piece of any hard wood; this, being covered with the bolt bar, will not show.

The linings, a, Fig. 1, are first to be bolted on, allowing them to rise 3/4 in above the iron; they can then be marked and trimmed for the wrest plank and bottom, B, the latter being dovetailed as described for a wooden back. In preparing to the soundboard the linings can themselves be taken to the requisite height. A similar curved slip is also required at the bent pinning edge, D, Fig. 1, and as the bed, E, for the top of the soundboard is continuous, a slip will be necessary here also. These slips are only 1/4in thick, the insulating felt making up the difference. This felt can be at option either continuous like the lips, or only in small pieces for the screws to pass through, leaving the intervening spaces free. I may here mention I have tried india rubber instead of felt, but with no improvement to the tone.

Step 7: The Shape of the Bridges

The next thing will be to ascertain the shape of the bridges. These are better of beech, though for the soundboard either close-grained birch or American maple will answer nearly as well. The top or plank bridges must be selected with the flowery side up and cut especially where the pins are in a straight line, a little across the grain.

The scale and shape of bridges are set out at one and the same operation. The first step is to rule a line about 1/4in. above the bottom of the wrest plank (see dotted line, F, Fig. 1), to serve as a basis of measurement.

As to give the lengths and striking distance of every string would tend rather to confuse rather than assist, I will confine myself to that of the C's, the top bridge being taken first. Commencing from the treble C, the distances above are 5/8in., 3/4in., 1 1/2in., and 2 3/4in., and the G one-fourth below 3 3/4in. Lines ruled between each of these measurements will suggest the necessary curve of the treble bridge, the remainder being continued in a straight line parallel to the plank.

Measuring from the striking distance of each C respectively 3in., 6in., 11 1/2in., and 23in. will give that of the lower bridge (see dotted line, H, Fig. 1), the remaining part, it wil be noticed, now taking a hollow curve so as to rapidly increase the vibrating length to the extreme limits of the back; the next C, being the first covered string, will be on the bass bridge; its length is 33in. - this bridge, like the last, being carried as low as possible.

As at this stage the operator will probably not have provided himself with a hammer rail from which to take the top scale, it may assist him to know that the first bridge pin being 2 1/2in. from the outside treble lining, the first C will be 7 3/4in.,* the remainder having a space of 6 7/16in. between them along the line of strike.

The bottom scale, which it will be seen is contracted, can be obtained by counting the pins on the iron back.

{* best guess}

Step 8: Gluing and Marking Off the Bridge

The bridge can next be glued - that of the soundboard being fastened with 1/2in. screws from the back, as their weight here will be rather an advantage, and it is essential to have the bridge firmly fixed.

The next process, after gluing down the soundboard, will be "marking-off" for the pins. As, to do this, a top scale will be found necessary, I shall be happy, for the convenience of such as require it, to send on on pricked paper for 1d. stamp. This can be tacked on a slip of wood, and the holes bored though for the marking-off pins to rest in, care being taken not to damp the paper as this would lengthen it to an extent that it would throw all wrong.

W. H. Davies, Liverpool

(from The English Mechanic and World of Science vol. 27, July 26, 1878, p.489-490)

Part 3
For background, try reading "The Piano Shop on the Left Bank" by Thad Carhart. While reading I learned lots about pianos, while all the time he was learning about himself...
&quot;The wood now almost universally used by European pianoforte makers&quot;, wrote Samuel Wolfenden in <em>A Treatise on the Art of Pianoforte Construction</em> in 1916, &quot;is that of the <a rel="nofollow" href="http://beta.uniprot.org/taxonomy/3329">Picea excelsa</a>, the widely grown <a rel="nofollow" href="http://en.wikipedia.org/wiki/Norway_Spruce">Norway spruce</a>; sometimes, however, <em>Abies pectinata</em>, { <a rel="nofollow" href="http://en.wikipedia.org/wiki/Abies_alba">Abies alba</a> } a very similar wood, indeed scarcely indistinguishable, takes its place. In the trade the wood is called 'Swiss pine,' but it must not be confused with <em>Pinus Helvetica</em>...In America a similar wood is yielded by the <a rel="nofollow" href="http://www2.fpl.fs.fed.us/techsheets/SoftwoodNA/htmlDocs/piceaglauca.html">Picea alba</a>.&quot;<br/>
&quot;Pine&quot;, wrote Charles H. Snow in <a rel="nofollow" href="http://books.google.com/books?id=ZVMDAAAAYAAJ">The Principal Species of Wood</a> in 1908, &quot;is prized because of a combination of strength, elasticity, light weight, working qualitites, and, until recently, wide spread availability...Thirty-nine of the seventy known species of pine are found in the United States. These with their woods are separated into two groups known as <em>hard</em> and <em>soft</em> pines.&quot;<br/>
Once again, another awesome job. How many parts will there be? It looks really interesting to try out, probably a bit to hard for me though.

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