I'm posting these lecture notes for the convenience of the NYCDOE Band directors attending a seminar on woodwind maintenance.
These are my lecture notes from a clarinet maintenance class I used to give at MSM. It quickly outlines disassembly and reassembly and some basic solutions to problems you might be able to work out for yourself.
MSM Repair Seminar 2014
Mechanics of the instrument: Terminology
pivots and rods
-Pivot screws are the small pointed screws at each end of the key. Most of the lower joint keys are held on by pivot screws.
-Rods are the cylindrical, smooth screws that span the entire distance from post to post. Top joint is mostly held together using rods.
flat springs and round springs
-Flat springs are found on the register key, side trills, and throat A key. One end is attached to the key and the other contacts the body of the instrument.
-Round springs most often protrude from posts and need to be secured behind a “catch” at the opposite end.
closed keys and open keys
-Closed keys are keys that are sprung with the pad touching the tonehole. The key movement opens the key. Closed keys need to have sufficient spring tension for the pad to seal securely against the tonehole.
-Open keys are sprung with the pad sitting away from the tonehole, and the key action brings the pad down to the tonehole. Open keys need only be sprung heavily enough to raise the weight of the key itself. A heavier spring tension can improve key response speed, but too much tension is tiring to the hands.
binding and free
A key is considered to be binding if it doesn’t move completely freely when assembled without spring tension. A bind can be caused by wood shrinkage, causing the space between the posts to be too short for the key. It can also be caused by corrosion, congealed oil, or a bend in the rod or key. A key is free when it falls of its own accord when assembled without spring.
Tools of the trade:
1- Screwdrivers- Use the largest screwdriver you have that will fit in the screw slot. Screwdrivers that are too small can mar the screw slot.
2- Pliers- Use only smooth jawed pliers, and be gentle. Pliers should only be used to remove rods, never to bend keys. Grip the rods with the plier jaws at each edge of the screw slot to avoid squeezing the screw slot closed.
-Rods: unscrew until you hear/feel a click, gently remove with pliers, wipe off oil on paper towel, and immediately place back into key.
-Pivots: replace in post when not assembled.
Never leave pivots or rods on a table, they may get mixed up. Although they look similar, pivots and rods are not interchangeable.
Only work on one section at a time. Fewer disassembled parts=less confusion. Don’t clean the oil off the rods with tissue or toilet paper, it’s too linty. Use a paper towel, washcloth, or old tshirt.
As you reassemble the instrument, make sure all the parts are clean. Position the key on the body of the instrument and add a small bead of oil inside the post at the rod entry point. For keys held on by pivot screws, add a bit of oil at each end of the key. Line up the rod or pivot screw by hand, then pick up the screwdriver and gently tighten. If it feels like it is being forced, remove it and try again.
Rods should be tightened until they stop. Do not overtighten.
Buffet pivot screws for instruments 15 years old and younger have an orange or black plastic ring that permits it to sit in the post in a variety of positions. When reassembling the key, tighten the pivot screws until the key binds slightly, then back off a bit until the key is free. Try to keep the pivot screws at either end more or less even.
Selmer pivot screws, older Buffet pivot screws, and most bass clarinet screws don’t have this plastic sleeve and should be tightened in the post until they stop.
Engage each round spring as the key is being assembled. Be careful not to overextend springs or you might change their tension. Try to handle round springs as little as possible, and use a spring hook or crochet hook.
As you reassemble, be sure the tip of flat springs make contact with the metal plate on the body. This is especially tricky with the side trill keys.
Order of operations to reassemble top joint:
Thumb ring and index ring key
D/A ring key
Throat A, then Throat G#
Top 3 side trill keys all at once
Order of operations to reassemble lower joint:
LH C key
F#/C# (tricky spring! Use spring hook.)
F/C, then Ab/Eb
Right hand sliver key
Right hand rings
Left hand pinky spatulas
Common problems and simple solutions:
Joint Assembly: Tenon Corks:
Tenon corks should have friction through the entire width of the cork and should fit firmly but not tightly. Tenon corks are a gasket, meaning that they create a seal between the two parts. Cork is not airtight on its own, it needs cork grease to make a complete seal.
If your tenon cork has friction through the entire width but the joints still do not fit together well, you may need to fit the tenons. Brush a light coating of nail polish on the wood part of the female tenon (the part with the cork), both above and below the cork gasket. Be sure to go all the way around, and try not to get the nail polish into the corner where the tenon meets the body.
It may take several layers to do the job properly. Let each coating dry for a few hours before adding the next coat. If you rush it you’ll end up with a gooey mess.
If you go too far, either sand the spot lightly or use nail polish remover or acetone to remove the excess.
The best way to tighten loose tenon corks until you can get to the repair shop is with Teflon plumbers tape. One or two times around should do it. If you don’t get to the repair shop you may need to keep adding more and more as each layer compresses. Dental floss also works (preferably the waxed old school string kind), as does electrical tape.
Throat G#/A Key Adjustment:
Poor adjustment of the throat G#/A can cause the G# key to remain open even when it is in the closed position. When pressing the A key, there should be a minute amount of movement before the G# begins to come up. If you aren’t sure if there is enough play, raise the G# key, put a cigarette paper feeler under the adjusting screw, and pull out the paper, feeling for friction. If there is friction on the paper, turn the screw a minute amount (one minute if it were the minute hand of a clock) and repeat with the feeler gauge.