I just finished a major overhaul of this vintage Conn bari sax.
It was about 100 years old, and as such had some quirks in its design. Aside from the fact that it only went up to High Eb, it had a convoluted octave mechanism, which seems to be par for the course on these old saxes. Unfortunately, no two models I've seen have the same mechanism, so every time I work on one I have to re-learn how to set it up. This time, though, I took notes. When setting up this particular style of mechanism, corks should be installed on each point in the order shown. Notes on each point are below the picture.
Cork 1 is just an articulation cork on the lower octave key. The pad isn't visible in this picture, but it's on the other end of that arm. It should be installed first, and should be pretty thin. I used .4mm cork.
Cork 2 is another simple articulation cork that's barely visible in the picture. The arm it's on is the arm that connects the G key with the octave mechanism. It should also be pretty thin, and again I used .4mm.
Cork 3 holds the upper octave key closed when the octave touchpiece isn't pressed (i.e., on any note below middle C#). There's a piece of teflon there, too, to ensure smooth movement on what is a very small contact area. Its thickness will vary. It just needs to be thick enough to hold that upper octave key closed. I ended up using 1.0 mm cork.
Cork 4 holds the lower octave key close when the octave touchpiece isn't pressed (again, any note below middle C#)
- Corks 3 and 4 are mounted on the same arm, so their thicknesses are dependent on each other. That doesn't mean the corks should be the same size, but it does mean that, once you establish the thickness of cork 3, you need to carefully select a thickness for cork 4. It needs to hold the lower octave key closed without raising the arm, which would cause the upper octave key to open slightly. As you can see, it ended up needing to be pretty thick.
Cork 5 closes the upper octave key when the octave touchpiece IS depressed, but the G key is closed (for notes between middle D and High G#). Because of the design of this instrument, the G key and upper octave key are actually regulated to each other, meaning that when this mechanism is engaged, they both must hit their tone holes at exactly the same time. A cork that's too thick will prevent the G key from closing (and not just on notes that use the octave key. It won't ever be able to close). A cork that's too thin will allow the upper octave key to open on the notes between middle D and High G#.
This mechanism is made more complicated by the fact that that upper octave key pip is on the neck, meaning that the pip itself moves when the neck is rotated, while the key remain stationary. Different players like to have the neck set in different positions, so there's an inherent challenge in making sure the pad always covers the pip. The original neck tenon had a spud on it that fit into some sort of slot on the socket to prevent the neck from being twisted too far out of alignment. Unfortunately that slot was long gone, and had been replaced with a poorly soldered piece of brass rod. I ended up replacing the tenon and socket because both were severely out-of-round and damaged. When replacing them, I made a new slot out of the lip plate from a flute and installed it on the socket. I also installed a spud on the new tenon. I don't know how closely the "slot" matches with the original set-up since I didn't have an original to work from, but it was effective in allowing the neck to be rotated a little bit while ensuring that the pad is always covering the pip.
Here's the old tenon and socket:
You can see that the missing plating under socket and the crappy solder work on the bow-body joint were both there from previous repairs. I also ended replacing the brace that's partially visible in the first picture running between the socket and body. At some point that brace was damaged and lost one of its flanges, but instead of repairing or replacing it someone just globbed solder all over it. I replaced it with a brace from our scrap pile that's visible in the second picture at the bottom of the neck bow. That position is more solid and safer than having the brace attached to the neck socket, which can easily be damaged by the brace pushing into it or pulling on it if the instrument gets whacked.
This mechanism is made more complicated by the fact that that upper octave key pip is on the neck, meaning that the pip itself moves when the neck is rotated, while the key remain stationary. Different players like to have the neck set in different positions, so there's an inherent challenge in making sure the pad always covers the pip. The original neck tenon had a spud on it that fit into some sort of slot on the socket to prevent the neck from being twisted too far out of alignment. Unfortunately that slot was long gone, and had been replaced with a poorly soldered piece of brass rod. I ended up replacing the tenon and socket because both were severely out-of-round and damaged. When replacing them, I made a new slot out of the lip plate from a flute and installed it on the socket. I also installed a spud on the new tenon. I don't know how closely the "slot" matches with the original set-up since I didn't have an original to work from, but it was effective in allowing the neck to be rotated a little bit while ensuring that the pad is always covering the pip.
Here's the old tenon and socket:
And just to show the difference, here are before and after shots of that top bow:
