starting on the stops mechanism

Quite a bit of fabricating of parts for this mechanism; it's certainly more complicated than what traditional harpsichords have had for stops control (a simple lever at best, or just "reach in and push this part over a little").  But for the flexibility it provides, and particularly given the relatively small space the mechanism had to fit into, I am proud of how simple the design is, actually.  I've had this on paper for several years now, plan to use it on all my keyboard instruments, but this is the first actual test.

The one slightly non-trivial part was making the slots in the machine-rails; these are of poplar.  I was able to "drill-route" them using a sharp drill bit on the drill press, by drilling holes with diameters that intersect, then grinding away the rough sides that remain using the same drill bit, carefully working until a channel is produced that the drill can slide freely through from end to end.  Results look quite crude and home-made, but functionally it works fine, and perhaps the rough sides give a better grip on the screw eyes or something.  (These rails could also have been built out of strips and blocks glued together, like the way some harpsichord registers are made, if one wanted to avoid my non-Kosher sideways drill use and still do it with minimal tools.)

Guides for the rails, and several other structural supports, are glued to the back of the nameboard, which forms the basic chassis for this whole mechanism.  The guides, 1/4" dowels, are glued into shallow drilled holes.  The rest of the blocks are simply glued to the surface.  Although I tried to mask-out some areas where I thought I'd be gluing, turns out in every case I had to sand and scrape away paint and finish to place each new block as I went, and the masked areas never got used.  Oh well!  (This is the cost of pre-finishing parts as early as possible, on an evolving prototype design, rather than delaying finishing as long as possible.)

The stop knobs have to be threaded through first, and their screw-eyes installed, ahead of everything else, or else they can't be reached conveniently.

The rails slide into place over their guide-dowels...

When a stop knob is turned to the left or right, its screw-eye engages a slot on one of the rails.  The rails are moved by the machine pedal.  When the stop knob is pointing straight up, its screw-eye misses both rails, and thus the stop is in "manual" mode.

The backing plywood, and all the additional parts of the mechanism, are held with sheetrock screws, so everything can be disassembled at will.

The stops knobs were initially hanging down in a position past their normal full-out travel position, with the screw-eyes resting against the nameboard.  Here I have pushed them in slightly and turned them to engage with one of the machine rails, which are themselves resting in the full-out position with gravity.  Thus, the back ends of the stops dowels are now visible at the surface of the plywood guide holes, in their correct full-forward position (where I can reach them to attach the lower portions).

The lower dowel portions, I don't have a good technical name for.  The upper dowel turns with the knob, this part is rotationally stationary but it slides in and out with the knob.  Anyway, this portion, each one I have drilled with four holes so that the order of the stops can be re-arranged.  (Although I have already chosen the actual order of the knobs, now determined by the names painted on the nameboard, the ordering of some of the back-end mechanism may still change.)

The spring-force of the wire actuator arms on the rollers, along with the springiness of the thin 1/4" dowels themselves, gives each stop a gentle but positive "click" action, where it wants to be fully-drawn or fully-pushed-in, but not somewhere in the middle.

Here the four left stops are pushed in...

...Here they are pulled out.  The rollers turn through a small angle, which will be translated to pull-force by wooden arms at the outside ends of the rollers (not constructed yet).  The length of the arm will determine leverage of course; in most cases, the motion will be reduced 1/2x or 1/4x from the knob travel (which is about 1/2").

Here I've added the brackets which carry dowels for the machine-pedal carriage mechanism, not yet constructed.  The dowels slide back and forth with the motion of the pedal (transferred by bicycle cable).  Elements attached to the dowels carry inclined planes (the "carriage"), which along with rollers cause the rails to be pushed forward in sequence at the proper point in the pedal travel: first the top rail, then it is joined by the bottom rail.  Strong spring force pulls back the rails, and also the pedal carriage.

Here you can see that I have used the re-arrangeability of the rollers, to put stop #8 on the back roller, out of the sequence followed by the other seven stops.  The 8th stop is "sust", and it needs to reach downwards to control the damper-lift, which is more convenient to do from the back roller; most of the other stops will pull cords or levers to the back and above their corresponding rollers.

With all the knobs turned to the right, all stops are engaged with the lower rail.  Here, they are all in the pushed-in position...

...When I manually push the lower rail forward, all the stops move forward to the drawn position.  The difference is highlighted by the unpainted-but-finished section of the dowels, which becomes visible.  I may paint this region red, or something.