14 Considerations of Woodwind Pad Installation

1. INSPECT THE TONE HOLES

Tone holes should be free of cracks, blemishes, and all imperfections.
Tone holes should be clean, concentric (in-round), and perfectly level.
Extreme care should be taken when leveling a damaged or worn tone hole. If you are able to utilize non-invasive methods where no material is removed, do so. However, if you must re-face the tone hole, the less material removed, the better.
If a fine file, or other abrasive tool is to be used to reface a tone hole, insure that the final condition of the tone hole rim is such that it is finely polished, level, and free of sharp edges prior to pad installation.
On metal-bodied instruments, inspect the base of all soldered or brazed tone holes carefully for leaks or points of separation.

2. LEVEL ALL PAD CUPS

Care should be taken when striking the key cup against the flat surface of a jeweler's anvil with a soft-faced hammer. Strike the key cup gently on its rounded edge. Striking the tone arm across the center-top surface of the key is sometime warranted, however, avoid unnecessarily striking a key cup directly on its top surface on either side of the tone arm.
Avoid damaging key pearls, if present.

3. INSTALL CORKS AND OTHER SILENCERS TO THE KEYS AND LEVERS

When you first remove corks, felts, and other silencers from the keys and levers, note their relative placement and thicknesses. If they were in close adjustment initially, by duplicating these dimensions (or just slightly thicker) you can avoid having to make excessive adjustments during the final assembly.
When applying cork material (pre-treated with contact cement) to keys and levers (after heating the key-arm and pressing the cork against the hot key) all surfaces must be free of grease and other contaminants.
Trim all corks and felts neatly, using a sharp single-edged razor blade.
Felt material is best affixed to keys or levers by applying contact cement to both surfaces; allow both surfaces to dry thoroughly ('tacky') before putting the felt in place. (I prefer to avoid the use of hot glue sticks.) Finally, trim away the excess neatly with a sharp single-edged razor blade.

4. AFFIX THE PADS INTO THEIR RESPECTIVE PAD CUPS

Select a pad of the right style, thickness and outside diameter. The pad having a straight edge, should fit exactly within the edges of the key cup, leaving no visable space at the peripheral edge. Generally speaking, if the exact pad diameter is not available, select one that is just slightly oversized (as opposed to under-sized). When using a 'stepped' pad (i.e. soprano clarinets) the resulting fit should be loose enough so that you can 'float' it in the cup. The resulting effects of the pad skin "pooching" a bit, can be resolved by gently ironing leather pads, or moistening the skin of a bladder pads. Always try to match the pad's style to be consistent with the original manufacturer.
Pre-treat a leather pad with a water-proofing conditioner.
Technicians will often prefer the light-colored shellac with the bladder pads, and the dark shellac for the leather pads. While many tech's use a hot glue gun (low temperature heat-sensitive polymer), this material seems to be in disfavor with most specialists. Whichever adhesive you use, be sure to apply a sufficient amount, so as to provide an adequate even coating on the entire bottom surface of the pad. Generally, bladder pads have the option of being 'floated' in the cup, while leather pads are most often just set evenly in the cup.
Once a leather pad is in place, and before the adhesive cools down, hold the cup firmly against your cutting board and rotate the pad in the pad cup a full 360 degrees to help assure that the adhesive is evenly distributed and that the pad sets evenly and completely within the pad cup. Visually sight along the edge of the key cup. Now, rotate the key to make sure that the pad sets evenly throughout the entire pad cup. You may now set the key aside to cool in a level position, to prevent it from shifting.

5. STRAIGHTEN THE LONG SCREWS (STEELS)

On steels longer than about 3 inches, you will be required to straighten in in shorter sections, or subdivisions of the total length. This is to prevent the steel from 'whipping' out of control when the bench motor is turned on. After straightening each shorter portion of the steel, blend-in its entire length by drawing a small hammer handle (drilled with a 1/8" hole in its bass) over the full length of the steel. CAUTION: Be sure to support the end of steels longer than about 3 inches when operating the bench motor! Also, be careful when drawing the hammer handle along the length steel, as too much force will cause the steel to twist on itself, ruining it.

6. CHECK THE POST ALIGNMENT WITH YOUR STRAIGHTENED STEEL

This step is relevant only to metal-bodied instruments. DO NOT try to drift posts which are placed in a wood, composite, or hard rubber bodies. Mis-aligned posts problems in these body materials require that they be removed, re-set and epoxied back into the correct position.
The straightened steel should be able to fall easily through its relative series of steels by only the force of gravity. If the steel does not fall through easily, either the steel is still out of alignment, or more likely, one or more of the posts are out of alignment with themselves.
Problems associated with post alignment are geometrically proportional to the number of posts present on a particular stack. The order with which you approach this problem is critical.
A post can become mis-aligned by being knocked out of alignment in 3 relative planes: (north/south, east/west, up/down) and any combination or permutation of these 3 planes. For example, posts can sometimes become slightly twisted radially on themselves, or they may be caused to lean up,down, or sideways; they may also be pushed into or pulled away from the body plane.
Be careful when tapping posts directly soft-soldered to the body, as they may be jarred loose or knocked off. This is usually less of a problem on posts brazed to a rib, where the rib is then soft soldered to the body.

7. CLEAN AND LUBRICATE EACH TUBULAR HINGE THOROUGHLY

Occasionally, hinges become glazed inside from corrosion and coagulated oils. Clean the inside of each hinge with alcohol on a pipe cleaner.
On corroded hinges, or hinges which have undergone replating, you will have to run the appropriate hinge tube file through them prior to cleaning them with the pipe cleaner and alcohol. Following this cleaning procedure each hinge should be treated with a drop or two of good quality key oil.

8. CHECK EACH KEY OR LEVER IN POSITION ON ITS RESPECTIVE STEEL

If a key or lever does not spin freely in position on its relative steel, then you can be sure that the key or lever will not operate properly when assembled. This is where you will have to use the 3 - Point pressure method to locate areas of misalignment.
Occasionally, a hinge will exhibit compound alignment problems ("S-shaped") in which case you will have to isolate each unique area of misalignment and solve each problem individually.
If a hinge is exceptionally difficult and gives you problems, you would be best advised to re-verify the straightness of the steel from time to time, and then proceed with straightening the hinge. Re-lubricate the hinge with a good quality key oil before proceeding.

9. INSTALL THE KEY(S) OR LEVER(S) ON THE INSTRUMENT

Preset each spring "load" and spring angle prior to assembling the stack of related keys and or levers.
In instances where there are many keys and/or levers on the same steel, you will want to assemble the individual elements on as they occur on the stack, sliding the steel along as each element is placed in position. Occasionally, you will be required to put multiple keys in a proper arrangement prior to running the steel through them.
Occasionally some springs must be pre-engaged in a hole in the side of the key tone arm. Verify this unusual key design prior to installing the steel through the keys and posts.
Unless it is necessary, avoid engaging the spring load until after the keys and levers are in place. The keys and levers may then be checked to see that they operate freely and smoothly on their own weight.

10. ENGAGE SPRINGS and ADJUST THEIR LOADS

Each spring should exhibit a gentle curve away from its post in the direction of its load. Avoid making sharp bends in the spring as this will accelerate the fatigue factor and cause the spring to fail prematurely, usually next to the post.
When replacing springs, use springs which are identical to those which were placed on the instrument by the original manufacture; avoid mixing spring alloys and styles .
The "flare" on the end of the spring (which is pressed into the post) need only be 2 or 3 mm in length, and its width need only be just wide enough to result in a moderate resistance as the spring is pressed into the spring hole. Too wide a flare will be very difficult to remove in needed, and could actually damage the post Consider the next technician who may have to remove the spring.
Tapered needle springs should be installed such that the pointed tip extends only a millimeter or so beyond the spring cradle. DO NOT snip off the pointed tip when it exceeds the spring cradle too much; take the spring out and shorten its length. The main purpose of the tapered tip is to reduce the amount of friction affecting the key action.
Make sure the spring is not rubbing up against the hinge.

11. CENTER AND PRECISION - LEVEL EACH PAD

Perform these steps in the precise order.
Back-off all adjustment screws used to regulate key-to-key combination (stacks) on instruments having adjustment screws (i.e. flutes, oboes). This will allow you then, to isolate and precision-level individual keys, without experiencing interference from other keys and levers operating in conjunction. On keys stacks lacking adjustment screws (i.e. most saxophones) you will have to center and precision-level the 'primary key' in the stack first. Then proceed in order with the secondary keys (operating in combination with the primary key).
Try to avoid undermining all the hard work you've put into leveling and centering the key cup, and straightening the hinge, while precision-leveling each keys.
Use a leak light and/or a very thin mylar feeler gauge (.002") when verifying the seating of leather saxophone pads. On the low harmony clarinets and bassoons you should use a feeler gauge only, as leak lights do not work well on instruments with thick body walls. On bladder pads (flutes, piccolos, oboes, etc.) leak lights are relatively useless, and require the sensitivity that only a thin mylar feeler gauge offers.

12. REGULATE ALL ARTICULATED KEYS AND LEVERS

All key articulations must touch the tone hole at precisely the same instant. Additionally, all pads on a stack must result in identical pressure (360 degrees around the pad) as the primary key is gently closed with very light pressure. I like to compare this pressure to the amount of force that it would take to push a pea 1/2 of an inch across the surface of a table.

13. MOISTEN, WEDGE, HEAT - IN THE PADS

For student flutes, soprano clarinets, oboes, bassoons, and saxophones, lightly moisten each pad and gently wedge them in a closed position. Do not exceed the pressure that would be used under normal playing conditions!
Heat each key cup with a heat gun (or alcohol lamp) to cause the keys to heat up and settle-in. This also allows the moisture to vaporize, and, as a result forms a gentle "seat" in each pad. Avoid excessive heat on bladder pads which have been 'floated-in' with shellac. Allow the 'wedged' instrument to set overnight before removing the wedges. Please note, visable seats are considered inappropriate on professional flutes. These pads are only gently clamped or wedged (dry, no heat) after the pads are precision-leveled.

14. FINAL ADJUSTMENT

After the wedges or clamps are removed, allow the instrument to set for at least 2 hours before re-checking the individual pads for levelness and the combinations for regulation.
Remove all "lost motion" present in combinations.
Play - test according to the unique testing requirements of each instrument.
If possible, have a fellow woodwind technician check your work.