Minolta MC W. Rokkor-HG 35/2.8: Cleaning the aperture blades

[Andreas Thaler]

This article refers to

Minolta MC W. Rokkor-HG 35/2.8: Removing and cleaning the aperture blades

Since I couldn't completely remove oil from the aperture blades of my MC 35/2.8 when installed, I tackled it thoroughly. The aperture register with the aperture blades is removed and cleaned of oil using Zippo lighter fluid. The candidate Removing the optical components and removing the...

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which also deals with cleaning the aperture blades, but I removed there the blades so that I could thoroughly clean the aperture register.

Here I show the simpler version, which is less sustainable, but may be sufficient in one case or another.

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A nice 35 from my inventory, it was deoiled in the workshop a few years ago.

Meanwhile there was oil on the aperture blades again and the aperture only wanted to work in slow motion.

After getting a briefing from Matt Bierner on what to expect during disassembly, I set to work.

Using the vacuum pad, which are hollow rubber cones cut at the top (see also pictures below), I unscrew the decorative ring.

The spanner wrench loosens the retaining ring for the front lens, which can then simply be unscrewed.

The lens sucker lifts the front lens out of the tube.

The top of the lens has a water-soluble marking for orientation.

The assembly above the aperture blades, consisting of two lenses, can be easily removed using the spanner wrench. I then hold the unit with two fingers and rotate the lens until the assembly is free.

This is quicker and the movement is even. This is particularly important when screwing in, as it prevents the ring from jamming in the thread.

The top of the aperture register is exposed.

We continue on to the rear of the lens.


Dismantling to the bottom of the aperture register:

Overview

Small screws are volatile, they are safe here.

 

[Andreas Thaler]

At the location of the oil problem: rear …

… and front

Zippo lighter fluid and several cotton swabs are used for cleaning.

I dip the aperture blades on both sides with lighter fluid and then move the aperture so that the oil is washed out. The cotton swabs absorb oil and lighter fluid.

The Dremel Versatip with hot air nozzle allows the lighter fluid on the aperture blades to evaporate immediately, leaving the oil behind.

This way the cotton swabs „know“ where there is still work to be done.

After a few cleaning cycles, the aperture blades appear oil-free.

After the aperture opens and closes properly again and the blades are dry, reassembly begins.

The spanner wrench back in action.

The front lens receives an extra cleaning service with products from Zeiss.

This time the vacuum pad rotates in the opposite direction ...

… and is turned moderately firmly into the final position with a second one.

Reassembled the 35, we are happy with the appearance of the aperture blades

This expedition, which lasted about an hour, required fewer tools and materials than usual.

Very pleasant

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Conclusion

• Not difficult at all and went quickly.
• It remains to be seen whether the cleaning was sustainable or whether it needs another pass (what was the case here, see the link to the follow-up post at the beginning of this article).
• As long as the old grease on the helicoids, which is now becoming liquid, is not removed and the screw is re-lubricated, there will continue to be oil buildup.

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