Reassembling hexanon 57mm 1.4 rear diaphragm linkage

[pleto]

Hallo all,

after some time I was able to almost finish the cleaning and repair of this lens.

Alas I needlessly disassembled the rear diaphragm linkage: when opening the flange a bunch of spheres came of and went scattered.

I tried to reassemble this structure but I was unable to put spheres in place, plus the plastic black linkage seems to small to fit into the structure so there is no way to put it all back together, at least for me.

Any help would be appreciated


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#2

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[visualopsins]

Just guessing here.

Looks like you have a retaining ring, a ring that moves the aperture coupling deeper into the lens, and a ring to help keep the looks like 6 ball bearings in place.

Maybe plastic ring should have been inserted before some other parts?

[BrianSVP]

Ugh, it's almost always a bad idea to disassemble a bearing race on these old lenses, as they are never easy to put back together. At least this one appears to have a relatively small number of ball bearings. In some, you'd be putting 70-80 tiny bearings back in place rather than 6!

Typically, in a race like this one, there is a beveled surface upon which the bearings sit that hold the rotating inner ring in place. Since the contact surface is with the bearings themselves rather than the outer ring, without them in place, the inner part will simply fall through - this is why it seems "too small."

The easiest way to deal with this is to grease up the surfaces so you can place the ball bearings back in with tweezers without them rolling away to who knows where, then once everything is secured, dunk the whole thing in solvent to clear the excess grease out.

In fact, that's probably the best way to clean these in the first place rather than disassembly. Simply put the whole mount in a jar of naphtha or similar and let it soak. If you have an ultrasonic cleaner you cans submerge the jar in while the solvent works, even better. Just be sure to do it outside or somewhere very well ventilated, since solvent fumes tend to be quite flammable and aren't exactly healthy to breathe in, either.

Once everything has been cleaned dried out, put a drop or two of machine oil, 3-in-1, or similar into the race to keep the bearing surfaces from rusting.

[RokkorDoctor]

[BrianSVP]

Very true. The flip side, though, is that it can a great source of ball bearings for aperture detents, particularly the really tiny sub-mm ones like Rokkor lenses often use and that are so easily lost. I took apart a Vivitar Series 1 zoom lens 7 or 8 years ago that provided enough bearings to probably last me a lifetime of lens repairs! There had to have been at least 100 bearings in there.

[pleto]

[BrianSVP]

Well, I happened to have another of this same lens, and I ended up figuring out a way to reassemble the bearing race more easily. It's been a year and a half, but maybe you will still find this useful if you never managed to get it back together.

This requires the lower barrel/helical be separated from the lens, since you are going to be adding parts from the top. Unfortunately, to do so, you also have to remove the aperture ring and the various attachments.

There are two set screws that tension the half and full stop spring/ball detents - removing the screws first will make it less likely that you lose the springs/balls when you disassemble.

1. Find a flat piece of styrofoam, and push the black plastic ring, lever side into it so the ring bottom with the aperture lever of the ring sits completely flush with the styrofoam surface. You will be stabbing the aperture lever and other projecting bits into the foam. This will hold the ring in place and at the correct vertical position as you replace the ball bearings.

2. Drop the lower outer barrel piece over the plastic ring so the ring is situated in the middle, with the mount side of the barrel also resting flat on the styrofoam.

3. Now drop in the thin copper ring with the cutouts in so it sits between the barrel and the plastic ring. the barrel has a lip that will prevent it from falling all the way through.

Now the tricky parts:

4. With a fine-tip tweezer, drop in each of the six ball bearings into the cutouts in the copper ring. They will sit between the edge of the copper ring and the beveled edge of the black plastic ring.

5. VERY carefully place the notched retaining ring on the thread and gently screw it in while holding the barrel piece as steady as you can. If all goes right, as the ring pushes down, it will seat all the bearings tightly into the bevel, allowing the plastic ring to spin freely. If any of the ball bearings pop out of the cutouts while you are tightening, you may be able to carefully push them back in with the tip of a needle. Once they have popped back in, you may need to tighten the ring a bit more to reduce play.

6. Once you've verified that everything is working, reassemble the helical, aperture ring, and mount.


I had tried the grease method I outlined above a few times, getting close but never quite getting everything together before it fell apart again. Once I came up with this method, I was able to get everything back together in only two tries.