nameboard and stops design

Well, now it's official, I have to finish this instrument by the end of this year!

As you can see, I have started fabricating the front panel (nameboard) and other elements related to the stops mechanism.  In order to do the lettering, I had to finally decide on the order of the stops:

8va sitar bsoon buff mod mute1 mute2 sust

...which is somewhat determined by the mechanical constraints, but turns out to be a good ordering from a functional point of view as well.  This gives something of a tonal continuum, left to right, from "buzzy" to "muffled".   Also, all of the stops which modify the tone after initial excitation, i.e., the "mutation" stops, are to the left.  On the right side are the controls which do other things than tone mutation: the moderator affects the initial production of tone, the mutes bring on silence.  Originally I had planned to make these mute stops "pull for sound", but now they will instead be "pull for silence".  This is mainly to make them work in a more-useful manner with the machine pedal (the left pedal): as the pedal is pushed down, adding sonic effects (which, generally-speaking, tend to reduce the total volume of sound), it is more likely that one will want to remove an active string from the pair, rather than add one.  Especially given that some of the effects (sitar, 8va) only affect one of the two strings in a pair: the first pedal position (part-way down) can introduce the effect while leaving both strings active, and then the second pedal position (all the way down) can mute the other string which doesn't have the effect, thus causing the effect to become much more prominent.

The stops mechanism will be attached to the back of the nameboard, fitting into the 4 inch space between the nameboard and the front of the wrestplank (usually nameboards are mounted right up against the wrestplank).  The entire assembly will be held in place with two screws, not glue, so that it can be easily removed, analogous to the keyboard and action.

Pulling the knobs will activate organ-type rollers which transfer the motion to the sides (four to the left, four to the right), where attached actuator arms will pull control wires forward through a distance of about 1/2" (3:1 leverage from the knobs).  Each stop mechanism will have a low-force spring return (low enough force as to not override the stronger spring-induced "click" which seats the stop knob into either the fully-pushed-in or the fully-pulled-out position.

The stop knobs can be rotated as well as pulled.  When the knob is pointing straight up, in the vertical position, the stop is in manual mode, and it can be pushed or pulled freely.  Turning the knob to the left engages the stop with pedal position 1, and to the right engages with position 2.  When stops are engaged to the pedal, they can no longer be moved by hand; instead, as the pedal is pushed down, first all the stops engaged to position 1 are moved outwards; as the pedal is pushed further, the stops engaged to position 2 also move outwards.  Releasing the pedal retracts the stop knobs, in the corresponding reverse order.  (Stops can be disengaged from the pedal, by rotating the knobs back to vertical, at any time, whether the pedal is down or up; the stops stay in whichever state they were in at the time they were disengaged.)

One issue yet to be figured out, is how to manage the spring force inevitably associated with the sustain mechanism (damper-lift).  Unlike all the other stops, which don't have an intrinsic spring force and which will have specific return springs added, the sustain stop has a relatively large amount of spring force to act against: it has to push all the damper springs down simultaneously, thus lowering the dampers away from the strings (in my unusual, dampers-from-underneath design).  This force is no problem to handle with the leverage of the dedicated sustain pedal (the right pedal).  However, in keeping with my gadget-centric design sensibility, I want to also treat the sustain function as "just another stop", susceptible to the handstop and machine-pedal mechanism like all the rest.  (Initially I avoided this conclusion, but at the very least I wanted to have a handstop which allows the dampers to be permanently disabled without having to hold the pedal down: this, after all, is the primary mode associated with historical pandalons (more often spelled "pantalons"), as well as with the hammered dulcimer itself, the underlying inspiration for this type of instrument.)

Having the sustain stop susceptible to the machine pedal, would seem to imply that the "click" force of the sustain handstop will have to be strong enough to hold the stop in the out position, against all the damper spring force.  I don't yet have a clear vision of how this will work.  I suspect the "click" will have to be too strong.  Using a mechanism involving an inclined plane which "plateaus" can eliminate the back-pull of the springs when the stop is fully out, but still something will have to provide all the force to move the knob in the first place.  Anyway, no clever solution here yet, but I'm seeking one...