Saturday, November 29, 2014

Buffet English Horn Bonus Post 2 - New Octave Mechanism

Those who know me know that I have nothing against automatic octave mechanisms on english horns. It's probably the defining characteristic of my personality. People who meet me often walk away saying "There's a guy who can appreciate a well-made english horn automatic octave mechanism." One of my first posts on this blog was about how to regulate such a mechanism on a Theo Markardt english horn, which was pretty elegantly made.

That being said, the automatic octave mechanism on my personal Buffet english horn was a bucket of junk. Most such mechanisms have only one octave lever, which is all you need. That one lever operates either of the two octave keys, depending on whether the G key (third finger left hand) is open or closed - that's also how automatic octave mechanisms work on saxophones. On this instrument, though, there are two octave levers, just like the manual (actually semi-automatic) mechanism that you'd find on most oboes and english horns. You could press either lever to activate the mechanism, and both had the same effect: they would allow the appropriate key to open depending on whether the G key was open or closed. So if, say, a saxophonist were doubling on english horn in a musical and wasn't familiar with how to use a manual octave mechanism, they could exclusively use the thumb octave lever just like they would on saxophone. Or if a player were feeling funky, they could exclusively use the side lever. And for those of us familiar with a traditional manual mechanism, you could use both levers just like you always have, and get the right "feel" while the automatic mechanism is actually choosing which key to open. It sound like a neat idea, but in practice it's pretty goofy. It's like buying a car with an automatic transmission, but driving it as if it were a stick-shift.


The original, automatic octave mechanism
A closeup of the original mechanism, showing multiple contact points that all had to be kept in adjustment
So the mechanism was over-engineered, had a clunky feel, and was finicky to keep in adjustment. Further, it was articulated to the G key by a long rod that made that key feel sluggish and heavy. I wanted to do something about it, and since there was no way to uncouple the levers from each other, I elected to replace the mechanism outright with a manual mechanism. Not wanting to sacrifice any parts of the existing mechanism, that meant making new keys from nickel stock.

Shaping the keys is a pretty simple, if time consuming process. After measuring and tracing parts of the existing mechanism, it was a matter of grinding and power sanding the rough shape into a bar of nickel, then filing and sanding by hand to refine the shape and remove scratches. Some parts had to be annealed and hammered on a mandrel or in a vise to create curves and angles. Here are a couple shots of the roughed-out thumb touchpiece still attached to the bar, after being hammered on a mandrel to create the curve that will allow it to wrap around the body of the instrument.


Side view
Top-down view
Only a couple parts had to be machined -one being a key cup for the upper octave key. The original lower octave key was usable in its unaltered condition, but a screw barrel had to be made for the thumb octave lever to connect to it. Those two parts were made from brass.


Brass rod in the lathe, ready to be machined
The new pad cup and screw barrel
The hinge rods that form the pivot axis for the keys were just nickel rod cut to the appropriate length, then center-drilled and reamed to accept the existing pivot screws. After that the various key parts were drilled out to the diameter of the rod and slipped on, then carefully aligned and soldered in place with silver solder. Finally, spring catches were made for both keys by filing down some scrap nickel. A small hole was drilled in each rod to accept the catches and they too were soldered in place. After a quick bath in descaling solution to removing the residue left by silver soldering, the keys were buffed and ready to pad/cork/install. The resulting mechanism is easier to use (for me, at least), feels more responsive, and it's simple, so it won't require constant monitoring and adjustment. 


General view of the new mechanism
Side view, showing the the thumb octave lever
Thumb touchpiece from the earlier pictures, polished and mounted
Closeup showing the new pad cup on the upper octave key, and the original lower octave key still in place
Side-by-side of the old and new mechanisms

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