The case side construction

These are 13 steps to a revolutionary new method of constructing harpsichords!!

 

 

An outline of the method used to construct these harpsichords:

  1. Boards of variable width and the correct thickness were glued together to make a baseboard of approximately the correct dimensions.  The baseboard was planed flat and the spine edge was planed straight and true.

  2. Various sticks and rulers were made.  An oncimetro marked out in Neapolitan once was made along with a stick with markings on it for each of the case dimensions, a stick with markings corresponding to the plucking points and string lengths, and a third stick with the lateral string spacings marked on it.  All of these were marked out using measurements in Neapolitan once.  The string lengths were based on perfectly Pythagorean scalings throughout the compass and a c2-equivalent scaling of 13 once from long E to d3 (yellow brass stringing) and a c2-equivalent scaling of 10 once for the bass notes from C to the short E string (red brass stringing)No measurements in millimetres were used.

  3. The position of the front keywell edge, the wrestplank, the wrestplank support blocks, the register gap and the lower and upper belly rails were scribed onto the baseboard using measurements in once from the drawing sketch and using the sticks that had been prepared for doing this.  The position of the line of the quill plucking points in the register gap was marked out and the position of the nut was marked out by measuring backwards toward the player end of the baseboard by the amount of the plucking points.  The line of the nut was then also scribed onto the baseboard.  Using the lateral string spacing stick the lateral spacing of each of the long c strings was marked onto the baseboard along the line of the nut already marked out.

  4. From the position of the marks along the line of the nut the string lengths for each of the long c strings were measured out, marked and scribed onto the baseboard.  A curved line joining the bridge ends of the string markings was scribed out using a light flexible piece of wood as a French curve.  A second line was also scribed out joining the ends of the string markings for the red brass strings in the bass.  These lines represent the final position of the bridge above the baseboard.

  5. The position of the bentside was marked out by measuring a distance of 6 once from the curved line representing the bridge position.  The lines of the tail and cheek were marked out on the baseboard and the outside edges of the baseboard were cut away.

  6. A soundboard was prepared and the angled line of the front, near edge of the soundboard corresponding to the near edge of the belly-rail soundboard liner was marked out and accurately cut.

  7. The soundboard was placed onto the baseboard and clamped to maintain its position.  The positions of the ends of each of the c strings was marked onto the soundboard in the same way that they had been marked out onto the baseboard.  Using the edge of the baseboard as a template the position of the outside edges of the baseboard were scribed onto the lower surface of the soundboard before it was unclamped.  The soundboard was then unclamped and the excess outer edges of the soundboard were cut away so that the soundboard had exactly the same shape as that of the baseboard.

  8. The soundboard was temporarily put aside while the case structure and internal framing were constructed onto the baseboard.  The wrestplank supports, keyframe supports, wrestplank, belly rail and the knees and internal framing were all glued in place.  The soundboard liners were all glued into their recesses in the knees and internal braces.

  9. The case sides were prepared and strips of chestnut were prepared of exactly the same thickness as the lower part of the cases sides for each separate case side.  The chestnut strips were glued and nailed to the lower edge of the baseboard and case framing with a projection of 2 decimi (a decimo is one tenth of an oncia).  Simple overlapping joins were used to join the ends of the chestnut strips as found in numerous antique Neapolitan instruments.

  10. The lower outside moulding was prepared and glued to the chestnut strip using special small clamps that were made especially for this purpose.  In order to clamp the outer moulding to the chestnut strip it was necessary to use the small projection of the chestnut strip below the baseboard and, of course, the outside lower moulding also projected and was positioned flush with the lower edge of the chestnut strip.  Because of the large thickness of the lower outer moulding, the bentside lower moulding was pre-bent using heat so that it had, in it neutral 'relaxed' position, roughly the same curvature as the bentside.

  11. The case sides were cut to length with mitres of the correct angle for each corner join.  Again the bentside was bent using heat before the final gluing operation.  The case sides were glued into position by sliding them into the gap above chestnut strip between the top edge of the lower outside case moulding and the internal framing.  The lower outside edge was lightly chamfered in order to ease the entry of the case side into this gap.  The case sides were clamped to the soundboard liners and to the outer ends of wrestplank and wrestplank supports.  The case side, trapped behind the lower outer moulding was self clamping in this operation.  This, of course, greatly facilitates and improves the speed of the operation when using hot glue with a very short working time.

  12. The two pieces of the bridge were glued to to the soundboard centring the bridge above the marks previously made on it.  After gluing the bridges to the soundboard, the bridge pin positions were marked out using the lateral string spacing stick but without any direct reference to or measuring out of the string lengths, the latter being the natural consequence of the previous marking out of the end of the c strings on the soundboard.  The nut pin positions were similarly marked out and the nut and bridge pins were nailed into place.  The soundbars and soundboard rosette were glued in position and the soundboard was glued into the case.

  13. The case was finished off with the case-top mouldings, soundboard mouldings, jackrail and jackrail supports, and by making and fitting the nameboard.

 

These are 13 steps to a revolutionary new method of constructing harpsichords!!

 

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