Causes of Shutter Squeak in Film Cameras and Precise Micro-Oiling of the Damping Gear

1. The physical and acoustic truth of shutter howling: It’s not the shutter, but the reflector-damped flywheel

Many photographers mistakenly thought that the curtain shutter was broken when they heard the scream like a sudden brake:

• Mirror Flywheel Damper: When the SLR camera is exposed, the mirror is bounced up by a strong spring at an extremely high speed. In order to prevent the reflector from violently hitting the viewfinder frame, causing the body to vibrate or the mirror to be shattered, a set of high-speed centrifugal damping shock-absorbing wheels (Flywheel Governor) driven by micro-rack and pinions are designed in the camera.
• Physical source of the whistling sound: The shock-absorbing flywheel rotates rapidly at an ultra-high speed of tens of thousands of revolutions in one thousandth of a second. When shipped from the factory, a trace amount of precision synthetic lubricating grease is applied.
• Oxidative deterioration of grease: After more than 40 years, the original grease evaporates and dries, turning into a sticky dry powder. When the flywheel rubs the axis of the dry-grinding copper sleeve at tens of thousands of revolutions, the high-frequency metal dry friction instantly triggers a sharp and harsh resonance resonance - this is the notorious 'Canon Shutter Squeak/Cough' in the film industry!
• Consequences: Excessive damping causes a delay in lifting the reflector, causing the exposure slow door to be inaccurate, or even getting stuck in mid-air and unable to be reset.

2. The disaster of violent oil injection: Why should you never spray WD-40?

In the film repair community, the most heartbreaking tragedy is when a novice picks up a can of WD-40 spray and sprays it violently into the camera:

1. WD-40 is a solvent cleaning agent rather than a long-lasting grease: It contains extremely volatile light solvents, which will quickly dissolve the remaining original damping oil in the machine after being sprayed into it. The whistling may disappear in the short term, but after a few days, the solvent will evaporate, and the metal friction will directly aggravate the wear and tear until it is irreversibly scrapped!
2. Oil-Soaked Curtains: Light grease has extremely strong capillary penetration and will cover the horizontal focal plane curtain shutter under the fuselage within a few days. After absorbing oil, the curtain becomes hard, brittle and sticky, the shutter opening and closing speed is completely disordered and collapses, and the film shows large areas of uneven black and white.
3. Corrosion of the silver coating of the reflector and pentaprism: Splashed atomized oil droplets adhere to the surface of the optical reflector, causing the coating to become foggy and spotty, completely scrapping the optical viewfinder.

3. Surgical-grade micro-oil injection tools and grease selection

Extremely demanding tools must be prepared before performing self-study:

• Grease Selection:
• Recommended purchase: Synthetic watch oil (Moebius 8000/9010 fine watch lubricant imported from Switzerland), extremely low viscosity, non-volatile and non-oil-spreading for decades;
• You can also use high-quality pure synthetic sewing machine oil or machine oil (consistency SAE 0W-20). Do not use cooking oil or butter.
• Oil application tool:
• It is absolutely forbidden to pour oil directly from the bottle!
• You must use a 1ml medical microsyringe with a very thin and long blunt dispensing needle (30G needle, outer diameter only 0.3mm), or a quenched and curved steel wire needle tip, and only pick up micron-level half a drop of oil (about 0.005ml) at a time.

4. Canon AE-1 / A-1 blind oiling operation process without removing the top cover and bottom

There is no need to disassemble the complicated top cover cable and shutter dial, and the target can be accurately reached from the bottom cover:

1. Remove the camera metal bottom plate: Use a high-precision cross JIS screwdriver to remove 2~3 tiny screws on the bottom cover, and remove the bottom cover smoothly.
2. Positioning damping flywheel gearbox:

• Turn the camera upside down with the lens mount facing you;
• In the deep gap between the battery compartment of the fuselage and the bottom of the lens mount, a set of tiny brass cascade gear shafts can be vaguely seen (located about 2.5cm deep in the lower left corner of the mount).

3. The needle tip accurately touches the lubrication point:

• Light up a strong flashlight to illuminate the depth of the dark groove. The long needle is suspended in the air and slowly inserted into the gap. Do not touch any surrounding wires or threads.
• Touch the tip of the needle extremely gently to the center shaft hole of the flywheel gear, and let the surface tension absorb the tiny 0.005ml micro oil droplet on the tip of the needle into the gap of the gear shaft.

4. Breaking-in and recovery:

• Press the shutter button to wind and release 5 to 10 times. As the gear rotates, a small amount of engine oil will quickly and evenly coat the axis.
• The sharp and piercing whistling sound will miraculously disappear completely within 3 shutter times, and the reflector will reset with a crisp "click"! Just reinstall the bottom cover screws.

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