On a full conservatory system oboe, regulating the lower end of the instrument can be a challenge for the uninitiated. Specifically, the keys controlled by the left hand pinky table present the technician with a lot of regulation screws and connections between keys that need to be adjusted to have little or no lost motion. The keys concerned are labeled below.
Before getting in to adjustments, there are a few things to check to make sure you have a solid set-up to build upon. If you're very confident that the instrument is already properly set up and just needs some tweaking, you can jump to step 7. It's always smart to mess with as few things as you need to.
1) Make sure the regulation screws at the bottom of the rod for the left hand pinky table are set to a neutral position. They're circled in the picture below. There needs to be a gap under each screw so that the pinky table can rock back and forth (at least a little bit) and won't contact the Eb closing spring and Bb linkage arm at the same time. If both screws are in contact at the same time, the Eb key may be held open. You'll adjust these screws later.
2) Also make sure there is a gap between the Eb closing spring and the arm on the back of the C key. The clearance in this spot is very tight, and it's not uncommon for the arm to press on the spring, which will hold Eb key open. If there is contact, the way I commonly address it is to file away a little bit on the bottom of the arm until there is clearance. Doing so will allow you to address this problem without altering the height of the C key or its relationship with the Eb key. The very tip of the arrow is where you want to look for clearance.
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3) Make sure the left hand pinky table is properly aligned and isn't bent. The Bb touchpiece sticks out further than any other key on the lower joint and is most prone to get bent. Make sure the arm leading to the Bb touchpiece is parallel to the arm of the Eb touchpiece and B touchpiece when viewed from above. Viewed from the side, they should also be parallel. (The left hand F touchpiece should also be parallel, but that's not involved in this procedure).
5) Make sure the B and Bb keys are at the same height. I'm assuming here that the pads have the same amount of protrusion from the key cups, and that the pads are already level to the toneholes. The height of the B key is controlled by a foot cork on the B lever that contacts the body. Keep in mind, if you change the thickness of that cork, it will alter the height of the B touchpiece. So it's generally better to adjust the height of the Bb key to match the B key. The height of the Bb key is either controlled by a foot cork on the bridge that contacts the body, or in the case of an instrument with a resonance key, the protrusion of the pad on the resonance key. More protrusion means that the Bb pad will be more closed, less protrusion means the Bb pad will be more open. If you need to adjust that, also look ahead to the next step and keep an eye on the bridge.
6) Make sure there is a gap between the bridge on the Bb key and the bridge on the lower joint. On an instrument without an adjustment screw or resonance key, you would just place a thicker cork on the bridge where it contacts the bell joint (slightly below the bell socket ring shown in this picture). On an instrument with a resonance key, make sure the adjustment screw is set to a neutral position. If there's still no gap, something is way out of whack. In any case, you would need to adjust the resonance key pad to change the height of the bridge, which will change the height of the Bb key (yuck).
7) Now that everything has been verified as being properly set up, you can start regulating! Turn the right hand screw from the picture to regulate B to Bb. Tightening it (clockwise) will make the Bb close sooner. Loosening it (counterclockwise) will make the Bb close later. In other words, if the B key is closing and the Bb is still hanging open, tighten the screw. If the Bb is closing but the B is hanging open, loosen it. Regulation screw are supposed to a little tight (that way they stay in place for a long time), but if it's really resisting, don't force it, lest you break the head and make it into a much larger (and more expensive) project. Always use the largest screwdriver that you can fit into the slot. The more purchase you can get, the less likely the screwdriver is to slip or damage the slot. And always rest the instrument on a stable surface while turning screws. Trying to hold the instrument in one hand and turn the screwdriver with the other is a great way to end up with a screwdriver in your arm.
If you back the screw out all the way and the B key is still hanging open, you'll need to adjust the bridge key from step 6 a little more. You can back out that regulation screw further to gain a little more ground. This will, of course, create a larger gap in the bridge key, and you always want to strive for the smallest possible gap on oboe keys, but if you've done everything correctly, that gap will be addressed shortly. For now, the concern is getting the regulation correct.
8) Once the regulation is set, you'll adjust the left hand screw in the above picture to remove the gaps (lost motion) throughout the mechanism. The idea is to eliminate the gap between the B and Bb touchpieces (from step 4), and create a minimal gap between the bridge keys (step 6). This should be achievable by turning that left hand screw. Generally you'll need to tighten in (clockwise) to close those gaps. If you turn it too far, though, it will hold the Eb key open by pressing on the closing spring. Keep an eye on that key and check it constantly. Open it with the right hand touchpiece and let it close, then do the same with the left touchpiece. Do it a few times with each one and make sure that it closes fully each time. If it doesn't, go back to step 2 and double check that there is a gap between the C key and the closing spring. If that's not the problem, you've overtightened the screw, or there may be an issue with spring balancing (the spring on the Bb linkage arm needs to be weaker than the Eb closing spring).
Go back and check your gaps one more time. Again, there should be no gap between the B and Bb touchpieces, and a small gap between the bridge keys. These are actual pictures from after I completed the setup on this oboe, showing those two spots.
Only after completing the B to Bb regulation should you proceed to the Eb-D trill regulation (when present), the B-C# regulation (when present) and the C-Eb regulation. Whatever you do from this point, do not change the height of the C key, as it can mess up the Eb closing spring.
There! That was easy, huh? What an elegantly simple mechanism the oboe has!
Regulating oboes can be extremely trying, but doing it well is absolutely essential for quality work. Oboes are know for being unforgiving in their adjustments. A poor setup can mean the difference between an instrument that sings and one that is impossible to control.
In other news, my cat usually dislikes the sound of the oboe, but while I was writing this post he finally got close enough to give mine a good sniff.
