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Flange stuck in a Hexanon 57mm - how to open?
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PostPosted: Fri Jan 27, 2023 8:56 am    Post subject: Flange stuck in a Hexanon 57mm - how to open? Reply with quote
Hallo Sirs,

I got an early version of an Hexanon 57mm 1.4



I was able to unscrew the front group and then open it by turning manually the front flange by means of isopropyl alcool, I let it seep through overnight.

I cleaned the rear of the front lens, then Iremounted it and the lens went well but I tried to open the front group again since I had some infinity problems, and it is now stuck permanently.

The front flange was screwed back rather gently the first time: nonetheless it is now stuck, and no amount of isopropyl poured in the gap (with the group turned upside down so as to let the liquid reach for the thread) can do.

I'm looking for smart suggestions, I'm not a technician so there might be some techniques that might work here.

thanks in advance





PostPosted: Fri Jan 27, 2023 11:35 am    Post subject: Reply with quote
It looks like this retaining ring is of the variety that doesn't have slots for a lens spanner.

The lens retaining ring is also likely to be made of aluminium, screwed onto an aluminium cell mount.

That type of construction has a tendency to bind up completely if you try and unscrew it by hand; as you grip the retainer ring you will be deforming it ever so slightly by your fingers squeezing it out of round, and making the aluminium-on-aluminium threads bind.

Usually the trick is to find something grippy that clamps fully around the retaining ring with even pressure, hence not deforming it, and then unscrew. A set of rubber lens retaining ring / beauty ring removal tools can come in handy here, but you can also try and find a plastic pot that just fits tightly around the retainer ring, or one that is just a fraction too large and line it with double sided sticky tape or some blu-tack.

Slightly warming the retainer ring first with your hand for 20 secs. or so may also help it expand just enough to loosen it a bit.


PostPosted: Fri Jan 27, 2023 4:31 pm    Post subject: Reply with quote
Infinity focus problem usually indicates a helicoid mis-adjustment, such as from incorrect reassembly.

However, to separate the part shown, a strap wrench may be correct tool.


PostPosted: Fri Jan 27, 2023 5:45 pm    Post subject: Reply with quote
Thank you both. I will try these solutions. Evil aluminium ....


PostPosted: Fri Jan 27, 2023 8:25 pm    Post subject: Reply with quote
visualopsins wrote:
However, to separate the part shown, a strap wrench may be correct tool.


That is worth a try.

However, bear in mind that a strap wrench is designed to provide good grip with a very large contact area; it is not designed to minimise component distortion and still has a fairy significant pinch-point where the handle presses on the strap. At that pinch-point it may even bind the threads tighter than trying it by hand. But there is little danger of any damage, so probably worth a try if you have one to hand.

Even professional repair shops sometimes have to improvise a bit and many repairmen make/adapt a variety of their own tools. No independent repair shop can maintain a stock of dedicated lens-specific repair tools and setting-aids for all models lenses ever produced...


PostPosted: Fri Jan 27, 2023 8:31 pm    Post subject: Reply with quote
RokkorDoctor wrote:
visualopsins wrote:
However, to separate the part shown, a strap wrench may be correct tool.


That is worth a try.

However, bear in mind that a strap wrench is designed to provide good grip with a very large contact area; it is not designed to minimise component distortion and still has a fairy significant pinch-point where the handle presses on the strap. At that pinch-point it may even bind the threads tighter than trying it by hand. But there is little danger of any damage, so probably worth a try if you have one to hand.

Even professional repair shops sometimes have to improvise a bit and many repairmen make/adapt a variety of their own tools. No independent repair shop can maintain a stock of dedicated lens-specific repair tools and setting-aids for all models lenses ever produced...


Like 1 Good points as always.

I have seen the correct tool set for these. I don't know what to call them. They are Y-shaped spanner-type wrenches with tabs in top part of Y which fit into slots in the ring to be removed.

Edit: correct tool is called a hook spanner


PostPosted: Sat Jan 28, 2023 12:04 pm    Post subject: Reply with quote
visualopsins wrote:
RokkorDoctor wrote:
visualopsins wrote:
However, to separate the part shown, a strap wrench may be correct tool.


That is worth a try.

However, bear in mind that a strap wrench is designed to provide good grip with a very large contact area; it is not designed to minimise component distortion and still has a fairy significant pinch-point where the handle presses on the strap. At that pinch-point it may even bind the threads tighter than trying it by hand. But there is little danger of any damage, so probably worth a try if you have one to hand.

Even professional repair shops sometimes have to improvise a bit and many repairmen make/adapt a variety of their own tools. No independent repair shop can maintain a stock of dedicated lens-specific repair tools and setting-aids for all models lenses ever produced...


Like 1 Good points as always.

I have seen the correct tool set for these. I don't know what to call them. They are Y-shaped spanner-type wrenches with tabs in top part of Y which fit into slots in the ring to be removed.

Edit: correct tool is called a hook spanner


I think an hook spaneer bears a similarity with a car filter removal wrench. Good suggestion, I will see if I find one.

In any case the group is already rather clean inside, only a few minuscule specks of duust remain.

My infinite problem was likely due to the fact that the entire group had been incorrectly screwed back by me, it didn't reach for the end of the thread, so it was too distant from the rear group.

I reinserted it correctly, it screwed back easily with no resistance and up to the last.

Now the lens performs correctly


PostPosted: Sat Jan 28, 2023 1:11 pm    Post subject: Reply with quote
visualopsins wrote:
I have seen the correct tool set for these. I don't know what to call them. They are Y-shaped spanner-type wrenches with tabs in top part of Y which fit into slots in the ring to be removed.

Edit: correct tool is called a hook spanner


For years I have been trying to find a good set of hook spanners for lenses; various Minolta tele lenses ideally require the use of a proper sized one on the nut holding the inner lens barrel onto the helicoid assembly (e.g. the MC TELE-ROKKOR 300mm/4.5).

So far I have only been able to find ones as used in the automotive industry, which unfortunately are far too large/course for use with lenses. The slots in which the hook spanner's hook(s) need to engage are usually very thin on the retaining nuts used inside lenses. Grinding down the tab/pin on an existing hook spanner will ruin the hardening of it, and I don't have the right facilities to re-harden the steel, so the hook would snap off easily on the usually quite stuck retaining nuts. I also don't have a workshop to make my own tools... Sad


PostPosted: Sat Jan 28, 2023 1:12 pm    Post subject: Reply with quote
pleto wrote:
In any case the group is already rather clean inside, only a few minuscule specks of duust remain.

My infinite problem was likely due to the fact that the entire group had been incorrectly screwed back by me, it didn't reach for the end of the thread, so it was too distant from the rear group.

I reinserted it correctly, it screwed back easily with no resistance and up to the last.

Now the lens performs correctly


Like 1

Looks like you are sorted!
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