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| BASSOON OVERHAUL SCHEDULE
By Lars Kirmser |
The following overhaul schedule represents what I consider to be a logical repair sequence for the complete overhaul of the German Bassoon. It is by no means intended to be entirely dogmatic, however. When special or unusual conditions arise (which is not uncommon with regard to Bassoon repair) the repairperson may find that it would be necessary to alter the sequence of the schedule. In such a case, the technician would merely alter the schedule so as to conform to their unique situation. As you will see, there are two optional sections included in the schedule. Steps 9 thru 17 are to be performed ONLY if the keys, post, body rings and accessories are to be replated. Steps 18 thru 20 are to be performed ONLY if the body sections are to be refinished.
1. REMOVE KEYS AND LEVERS
A. Check each individual mechanism as each key or lever is removed for the following:
- Swaging requirements
- Loose posts
- Spring tensions
- Key heights (travel)
- Key cup centered over tone hole?
- Pad condition (continuity, seat)
- Mechanical combinations
- Adjustment corks, felts, silencers
- Key hinge straight?
- Key steel straight?
Replace each steel and pivot back into its relative post for the time being.
Bell Section
Bass Section
- Low B Key (3)
- Low B and Bb Levers (4 & 2)
- C# Key (5)
- Low Eb Key (12)
- Low C# Lever (6)
- Low D Key Guard (if req.)
- Low D Key (11)
- Low D Lever (9)
- Low C Key (7)
Wing (Tenor) Section
- Whisper Key (13)
- C# Key (24)
- High A Key (23)
- High C Key (21)
- High D Key (20)
- Whisper Key Bridge Lever (16)
- C# - D# Double Lever (29)
- Whisper Key Thumb Lever (15)
- C# - D# Trill Key (30)
- C# - D# Trill Ring (31)
- E - F# Trill Key (26)
- Eb Trill Key (Opt.)
Because of the unique design of the Bassoon Boot Section, I will refer to it as though it were in fact two separate sections. The key mechanism which affects the tone holes on the treble side (usually lined with plastic or vulcanized rubber) will be referred to as the High Side of the Boot Section. The opposite side will be referred to as the Low Side of the Boot Section. This reference will be particularly helpful when the technician is required to remove the posts in the course of repair. Disassemble each side in the following order:
Boot Section - High Side (H.S.)
- All Key Guards (as required)
- C# Trill Key (41)
- G Ring Key (51) (if Bb & G Levers go beneath the G Ring Key hinge)
- Bb Lever (45) w/push rod
- G Lever (46) w/push rod
- F Key (49)
- F# Key (53) - F Lever (48) w/push rod
Loosen the F Lever via the lower post, then remove the F# Key followed by the F Lever
- Ab Key (55) w/push rod (on a 4 push rod system)
Tape and label the push rods on a 3 X 5 card
Replace all steel key guard screws with brass screws
Boot Section - Low Side (L.S.)
- All Key Guards (as required)
- Low E Key, aka “Pancake” (17)
- Bb Lever (42)
- Bb Key (43) (#1 push rod)
- F# Rocker (34) (#2 push rod)
- F# Key (32)
- Ab Lever (35) (present only on bassoons with a 3-push rod system)
- Ab Rocker (37) (#4 push rod, not present on 3-push rod systems)
- G Key (47) (#3 push rod)
- Boot Cap & Crook
2. REMOVE ALL STEELS
- Place all steels on the universal screwboard in the order in which they occur
- Dress all worn screw slots with a polishing wheel
3. REMOVE PIVOT SCREWS
- Place all pivot screws on the universal screwboard in the order in which they occur
- Dress worn screw slots with a polishing wheel
4. REMOVE SPRINGS (*opt.)
- Remove springs only if replating and/or body refinishing is to be performed
- Place all springs on the universal screwboard in their proper sequence (indicate whether they point upwards or downwards).
- Replace all damaged or worn springs at this time (use identical replacement springs).
5. REMOVE WORN TENON CORKS OR WRAPPINGS
- Avoid damaging or removing material from fragile wood tenons
- Inspect for split tenons; repair or regraft as necessary at this time
6. REMOVE ADJUSTMENT CORKS, FELTS AND PADS FROM KEYS
- Make sure that all adhesives are removed from keys, levers, and cups
- Take special note of the placement and relative thickness of all materials.
7. BUFF KEYS AND LEVERS
- Use a spiral-stitched muslin buff (approximately 1/2" wide and 6" in diameter) with white compound at a moderate speed (approximately 1200 RPM) Do not buff through the plating!
8. DEGREASE KEYS AND LEVERS
- Vapor degreasing (trichloroethylene) is preferred, however, be aware of local restrictions
Perform the following 9 steps ONLY if replating is required:
9. REMOVE BODY RINGS, KEY GUARDS, SECTION LOCK, ETC.
10. REMOVE POSTS
- Place post-locking screws in a clear plastic vial on screwboard.
- String posts in EXACT sequence on a steel wire as they are removed from the bassoon body.
11. STRIP KEYS, POSTS, RINGS AND ACCESSORIES OF THEIR PLATING
12. REMOVE PITS AND SCRATCHES WITH A FINE FELT - EMERY WHEEL
13. BUFF POSTS, RINGS AND ACCESSORIES WITH TRIPOLI FOLLOWED BY WHITE COMPOUND
- Use a pre-threaded piece of brass rod to hold individual posts when buffing
- Maintain their proper order as you string them on a copper wire
14. BUFF KEYS WITH TRIPOLI, FOLLOWED BY WHITE COMPOUND, THEN RED ROUGE
15. DEGREASE KEYS, POSTS, RINGS AND ACCESSORIES
- Vapor Degreasing (trichloroethylene) is preferred, however, there are more and more restrictions these days, so you may have to explore more acceptable chemicals to adhere to local restrictions.
16. REPLATE KEYS, POSTS, RINGS AND ACCESSORIES to BRIGHT NICKEL or SILVER
- Carefully run a small round file through the hinge tubing of the keys (after plating) to remove any excess plating residue, or buffing dirt inside.
- Clean all body posts and spring holes of buffing dirt or plating residue..
- String posts in their precise order on a copper wire for plating.
17. INSTALL POSTS AND BODY RINGS ON INSTRUMENT
- If no body refinishing is to be performed
Perform the following 5 steps only if refinishing body sections:
18. REMOVE THE OLD FINISH FROM BODY SECTIONS
- This may be effectively performed by using a commercial paint/varnish cold stripper.
- Carefully apply to one section at a time, being very careful not to get stripping solution on/in toneholes or inside the pretreated bore (or bore lining). You may want to mask the tone holes prior to application.
- Allow the solution to dissolve the old finish, which can then be removed with fine steel wool pads, followed by wiping with a clean damp cloth.
- After the surface is completely relieved of the old finish, and has been allowed to dry, smooth the slightly raised grain with a fresh steel wool pad (0000), or with a #400 wet/dry sand paper.
- You should repair any post hole damage or wear at this time
19. APPLY DESIRED STAIN/FILLER TO BODY SECTIONS
20. APPLY AT LEAST 2 or 3 base COATS OF A CLEAR-GLOSS FINISH
- This may be a varnish, nitrocellulose lacquer, or other acceptable finish
- Mask-off the tenons, toneholes and other parts that are not to be finished.
- Allow each intermediate coat of finish to dry thoroughly before rubbing out any imperfections with #400 wet/dry sandpaper.
- Allow the final coat to dry for at least 24 hours before proceeding with rubbing out and reassembly.
21. REFACE TONE HOLES (as req.)
22. SEAL ALL TONE HOLES
23. INSTALL POSTS AND BODY RINGS
- All posts should be held firmly in place
- Install post locking devices as necessary
24. CLEAN ALL BODY SECTIONS WITH A LACQUER CLEANER
- Only if the body was not refinished
- Do not use anything containing alcohol or abrasives!
25. INSTALL NEW TENON CORKS OR WRAPPINGS
26. RESPRING BODY JOINTS (IF REPLATING AND/OR BODY REFINISHING WAS PERFORMED)
- Use original springs only if they are still in perfect condition
27. CLEAN, FREE AND LUBRICATE ALL STEELS WITH THEIR RESPECTIVE KEYS
- Lubricate lightly after cleaning the hinge tube and before “freeing-up”.
- Replace steels on the screwboard as each one is worked with.
28. RECORK AND REFELT KEYS
29. INSTALL PADS (RIVITLESS KID LEATHER PADS)
- Cork pads are occasionally used in place of some of the smaller pads on the Tenor and Boot sections
30. ASSEMBLE, ADJUST AND LEVEL THE KEYS AS FOLLOWS:
Bell Section
General Considerations for each Key or Lever as it is installed:
- Tone hole
- Pad
- Key cup
- Key arm
- Spring
- Key guide
- Corks/felts
- Key travel
- Key hinge
- Steel (pin)
- Posts
External Considerations:
- Bell Crown
- External finish
- Brand/model stamp
- Ferrule (body ring)
Internal Considerations
- Internal finish
- Bore dimensions
- Tenon/Receiver
Bass (Long) Section
Preliminary Considerations:
- Swaging problems
- Loose posts
- Relative spring tensions
- Proper key height (travel)
- Key cups centered and leveled over respective tone hole?
- Pad condition/seat
- Mechanical combinations in close adjustment (if applicable)
- Adjustment corks/felts/silencers (appropriate type and thickness)
- Key hinge straight
- Key steel straight
- Replace each steel (pin) and pivot screw back into it’s relative post
External Considerations:
- External finish
- Loose posts or key guides
- Tone hole continuity (porosity, clean)
- Tenons (lubricated, in-round, cracked?, relative fit)
Internal Considerations
- Internal finish
- bore dimensions
- Screws protruding into bore
Bass Section Assembly
Low D key
- Relative adjustment between posts
- Pad continuity/seat
- Spring tension
Low D lever
- Relative adjustment between posts
- Cork/felt on bottom of lever determines the D key height (5mm)
Low C key - B lever - Bb lever
- Relative adjustment of the keys/levers between posts
- Check the C key spring tension (usually too heavy)
- Silencer cork/felt on the bottom of the C key, B & Bb spatulas
- The relative position of the B lever determines the C key height (5mm). This fine adjustment is made by either carefully bending the lever, and/or by adjusting the relative thickness of the lever’s cork/felt.
- The tab extending beneath the C key (from the D lever) must be adjusted such that the C key and the D key close at precisely the same instant.
- The B lever - Bb lever -C key spatula & D lever must all be level with respect to one another
Low B Key
- Relative adjustment between posts
- Pad continuity/seat
- Key height (5mm). This is adjusted by carefully bending the small lever on the key.
- Spring tension
Low Eb Key
- Relative adjustment between posts
- Spring tension
- Key continuity/seat
- Key height (2.5 to 3mm)
- Check roller
- Adjust the key spatula to the C# lever spatula
Low C# Lever
- Relative adjustment between posts
- Spring tension
- C# lever and the D# key should be on the same plane
Low C# Key
- Relative adjustment between posts
- Spring tension (in combo with the lever)
- Key continuity/seat
- Key height
Low D Key Guard
- Screws protruding into bore?
- Screw holes stripped out?
Wing (tenor) Section
Preliminary Considerations:
- Swaging necessary?
- Spring tension(s)
- Key height (travel)
- Key cups centered and leveled over respective tone holes?
- Pad condition/seat
- Mechanical combinations in close adjustment (if applicable)
- Adjustment corks/felts/silencers (appropriate material and correct thickness)
- Key hinge straight
- Key steel straight
External Considerations:
- External finish
- Loose posts?
- Key guides
- Tone hole continuity (porosity)
- Tenon condition
- Bocal receiver
- Upper ferrule (body ring)
Internal Considerations:
- Internal finish
- Bore liner
- bore alignment
- bore dimensions
Wing Section Assembly Order:
E - F# Trill Key
- Relative adjustment between posts
- Pad continuity/seat
- Spring tension (moderate)
- Cork/felt on key
- Key height (travel) 3mm
- Eb trill key (occasionally part of the C# - D# trill ring mechanism)
C# - D# Trill Ring
- Relative adjustment between posts
- Ring to tone hole insert relationship (if present)
- Pad continuity/seat (if present)
- spring tension (light)
- Cork/felt on key
- Key height (travel)
C# - D# Trill Key
- Relative adjustment between posts
- Pad continuity/seat
- Spring tension (light)
- Key height (travel) 3mm
- C# - D# trill ring to C# - D# trill key adjustment
C# - D# Double Lever
- Relative adjustment between posts
- Spring tension (heavy enough to close the C# - D# key adequately)
- Cork/felt on lever
- C# - D# double lever to C# - D# key adjustment
Whisper Key Thumb Lever
- Relative adjustment between posts
- Spring tension (moderate)
- Cork/felt usually on upper arm only
Whisper Key Bridge Lever
- Relative adjustment between posts
- Spring tension (light)
- cork/felt on lever
Whisper Key
- Relative adjustment between posts
- Pad continuity/seat
- Spring tension (light)
- Cork/felt/silencer on bridge arm
- Key height, minimal (travel off of the low E “pancake” key)
Note: The low E pancake key must close at precisely the same time as the whisper key (via the bridge lever) at the bocal pip
C# Key
- Relative adjustment between posts
- Pad continuity/seat
- Spring tension (moderate)
- Cork/felt on key
- Key height (travel) 2mm
Note: This C# key will “establish” the relative key height (travel) of the other adjacent thumb spatulas (whisper thumb lever, high A, C & D keys)
High C Key
- Relative adjustment between posts
- Pad continuity/seat
- Spring tension
- Cork/felt on key
- Key height (travel) 2mm
- Relationship to upper arm of C# - D# double lever (minimal lost motion)
High D Key (opt.)
- Relative adjustment between posts
- Pad continuity/seat
- Spring tension
- Cork/felt on key
- Key height (travel) 2mm
The Boot Section
Preliminary Considerations:
- Swaging necessary?
- Spring tension(s)
- Key height (travel)
- Key cups centered and leveled over respective tone hole?
- Pad condition/seat
- Mechanical combinations in close adjustment (if applicable)
- Adjustment corks/felts/silencers (appropriate type and correct thickness)
- Key hinge straight
- Key steel straight
External Considerations:
- External finish
- Loose posts or key guides
- Strap ring missing?
- Stripped - out key guard wood screws
- Tone hole continuity (porosity, level)
- Tenon receivers
- Ferrules (large body rings)
Internal Considerations:
- Internal finish on the high side (lined)
- Internal finish on the low side (dirty, requires resealing due to wood rot)
- End crook gasket (dry, spent)
- End crook (dented, otherwise damaged)
- boot plate (leaking, loose)
Boot Section High Side Assembly: Order
C# Trill Key
- Bb lever (H.S.) and G lever (if they go under the high G trill key)
- Spring action on Bb lever (light)
High G Ring Key
- Spring tension (light) This ring opens when the F lever is depressed and is closed by the combined light spring action of the F lever and F key.
Ab Key (H.S.)
- Key height (travel) 2.5 to 3 mm
F Lever
F Key
- Spring tension (light)
- The tone hole of this key will sometimes require “flattening”
- The key height will be greater than most other keys as it operates off the F# rocker push-rod (low side) and is a much larger key and rotates at a greater radius than the F# key
- Adjust the adjacent Ab spatula so that it is just a little lower than the F key spatula
F# Key (H.S.)
- The spatula of this key should be even with the spatula of the F key
- It’s key opening is dictated by the travel of the F key
All Key Guards
Assembly of the Low Side of 3-Push Rod Boot Section:
G Key
G Key Push Rod (#3)
- Spring action should be just strong enough to counteract the light spring action on the G lever (high side) via the #3 push rod.
- Run a pipe cleaner through the G resonance vent to make sure that it is not blocked in any way.
Ab Key (L.S.)
F# Key (L.S.)
- F# push rod (#2)
- The thumb spatula should be comfortably adjacent to the low E key when it is in the closed position; It is usually set too high and too far away from the large low E pad cup.
F# Rocker
Bb Key
Bb Lever (L.S.)
- The thumb spatula should be comfortably adjacent to the low E key when it is in the closed position; it is usually set too high and too far away from the large low E pad cup.
Low E Key ("pancake")
All Key Guards
- Install Boot Bouchon (Crook) Gasket
- Install Bouchon and Cap
Assembly of the Low Side of 4-Push Rod Boot Section:
G Key
- G key push rod (#3)
- Spring action should be just strong enough to counteract the light spring action on the G lever (high side) via the #3 push rod.
- Run a pipe cleaner through the G resonance vent to make sure that it is not blocked in any way
Ab Lever
Ab Rocker
F# Key (L.S.)
- The thumb spatula should be comfortably adjacent to the low E key when it is in the closed position; it is usually set too high and too far away from the large low E pad cup.
- F# push rod (#2)
F# Rocker
Bb Key
Bb Lever (L.S.)
- The thumb spatula should be comfortably adjacent to the low E key when it is in the closed position; it is usually set too high and too far away from the large low E pad cup.
Low E Key (pancake)
- The wing section and bocal must be assembled into the boot section for you to check the low E to whisper key combination. Any necessary adjustment can be made by carefully bending the whisper key bridge arm as required.
- Key height (travel) 3mm
All Key Guards
- Install Boot Bouchon (Crook) Gasket
- Install Bouchon and Cap
31. WEDGE / HEAT-IN PADS
- Lightly moisten pads, and gently wedge closed and apply moderate heat to pad cups with a heat gun.
- Allow to set overnight.
- Remove wedges and allow instrument pads to settle for an hour or so.
32. Make final visual/physical inspection and Play-test
33. Wipe the instrument clean
34. Blow lint and dirt from case
- Repair Latches, Hinges, Blocking as necessary
35. Ship it!
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