NikonGear'23
Gear Talk => What the Nerds Do => Topic started by: Thomas G on March 19, 2016, 14:32:03
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Some time ago I was able to acquire a 105mm 1:2.5 for a bargain.
The optics were fine, mechanically it wasn't so much and obviously it had been fuzzed around with non appropriate tools.
I started working on the lens some time in fall 2015.
There were a few obstacles to work through, abused screws, sticky dirt, and some super sticky glue in unusual places,
obviously work arounds of some kind.
Considering Roland's serials listing the lens belongs to the following group:
| Type | Lens | Country | Scr | Notes | Start No | Confirmed | End No | Qty | Date |
| Ai | 105/2.5 | MIJ | 5+ | | | 764011-897333 | | 157333 | (1977)-Sep 1981 |
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Post documentation.
All parts came apart with some effort.
The first show stopper was the front ring, which was stuck with the tube mount ring.
I was able to drill out the screw which usually keeps the main thread in position.
Unfortunately it did not improve the situation at the time:
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I figured that applying force may damage things and nibbled the 3 front screws out.
(I hope that they are not part of any adjustments system as I was not able to mark anything in the small space available)
One of the 3 holes shown:
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The whole disassembled lens cacrefully stored away:
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Front ring and tube mount ring were smoothere in 'the juice' for like 3 month.
A few days or weeks usually would do it but I had no time working on it anyway.
The juice is a proven combination of weapon oil, some synthetic engine oil and a solvent.
I finds its way into mechanically stuck threads, into tight fittings and such.
I deals with dirt and acids as well. Crawls under no so well sticking glue, even under well sticking but not well used glue.
Can be support with warming up the parts.
The issue was: I did not now is the threads were glued together.
Even worse: if the possible glue was of the epoxy type light heat will only make it stronger (up to about 180°...).
So I let it sit in the juice for a long time.
Juice shown in it's top coverable tin. The jelly is a result of some reaction, cool temperature and the dissolved solvent.
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A few days ago the ring assembly was taken from the juice and swiped clean on the outside.
Still stuck. The usual rubber tools did not do it.
Instead of heat the decision was to use cold.
The idea was to quickly deep cool the inner ring while keeping the outer ring warm.
A basic device was build to prevent the vapor cooling spray to boil away on the outer ring and concetrate the thermal effect on the inner ring.
Device and deep freeze spray:
(related: http://nikongear.net/revival/index.php/topic,2411.msg43070.html#msg43070 (http://nikongear.net/revival/index.php/topic,2411.msg43070.html#msg43070)
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The procecure was as follows:
- use high friction protection gloves of the sticky type to prevent skin irritation or damage as caused by cold
- spray one full turn of the freezing solvend on to the inner ring
- immediatly try to twist of the rings from each other (with some force, if need be)
It worked on the first attempt:
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Now it's time for re-lubing (again, too sticky) and re-assembly
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Hello is this the same version as this lens? :o :o :o
I just overhauled one a month ago. Gonna write a teardown one of these days in richardhaw.com where i publish my teardowns.
There is a teardown on the net made by somebody else.
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Wong photo sorry :o :o :o
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Neither one. Quite similar to the second but only F/22.
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Thanks for the freezing tip! Recently Bjørn and I used heat to free a stuck glass element from a lens housing.
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Neither one. Quite similar to the second but only F/22.
oh, that's basically the same lens mechanically with very little differences :o :o :o (and optically) there wasn't a lot changed from K to Ai. Servicing this lens was a joy for me.
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Thanks for the freezing tip! Recently Bjørn and I used heat to free a stuck glass element from a lens housing.
it might be pitch. :o :o :o heat is very good for that. i learned to heat pitch from my mechanic before when he was fixing my car's undercarriage. i was told that older japanese cars use them for waterproofing ::)
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i need to get that freezing spray :o :o :o
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Works as well: Put it into a freezer and later a little heat on the outside part (just tested this a couple of weeks ago)
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Yes that is the basic idea of how it works - But also aluminum expands more than glass ;)
Richard, What do you mean by Pitch?
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Richard, What do you mean by Pitch?
He meant "tar", I suppose.
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Richard, What do you mean by Pitch?
yes, Akira-san said it correct, black tar. :o :o :o
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Ok,,, next question; What do you mean by Black Tar?
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Ok,,, next question; What do you mean by Black Tar?
Black tar is basically the black liquid goo that careless dinosaurs step into, leading to their death :o :o :o
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OK, and where do you apply it if your not prehistoric?
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The pitch or black tar is used to fix the lens to the rotating platform when they are ground. Perhaps it is also used as anti-reflection paint and applied to the edges of the lens elements?
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Thanks,,,
But it still really doesn't make any sense to me ::)
Flat black paint is used for the glass edges and the rear opening on some lenses,,,
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Well, I was just guessing its use as anti-reflection method. But tar is pitch black!
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;D
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Hello sorry for not being clear :o :o :o
some lenses have it to glue it with its casing. i was shown once where it was baked to separate it from the glass. i asked and i was told "pine sap" basically pine resin. the reason thy probably use this is because it is pliable when warm. according to the repairman, telescopes use this more than camera lenses. i guess this is an old technique
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*sigh, well, the Utrecht event came close and I had to hurry.
Thus I did not take as many photos as planned.
Bringing the f-stop klick spring back.
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moving on. Putting little screws back in places.
Carefully following the notes taken on the protective sheets of (news)paper.
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...
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approaching the next step which developed the potential for headaches and twisting muscles and brain.
the little offender is the spring which, by design, pulls back the diaphragm when fitted properly.
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1 which proved to be an undertaking. taking long.
2 finally my beloved and uncomplaning wife helped to add hands.
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we reached the 'give me five' status, at the same time realizing that we missed to place the following:
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unfortunately these belong inside. what a disapointment.
at about 8:30pm I started to dismantle the lens again, making room for placing the forgotten parts.
then fitting the little spring again.
back to working state it still looks like having had a rough life, now working like a charm again:
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Summary:
The lens works better than my other example, I still feel it's a bit stiff in dianling the distance.
John and other shared that this is the 'right' drag for this generation of lenses.
Time will tell if I'm going to peplace the grease again.
Thoughts:
- get different types of grease
- make a more descriptive sequence of photos of the individual steps (next time)
- keep the little parts jars in the right sequence (for sure)
- learn how to take the helicoil apart (there seems to be a trick I do not know yet)
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Wonderful write-up! You are a very brave (and talented) soul.
Thanks for sharing. Some day when I find a few quiet hours I need to take apart a very early 50mm f/2 Nikkor that has an aperture ring that takes muscle to turn (but only in one direction--the other is quite strain-free).
Dan
Santa Barbara, CA
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Summary:
The lens works better than my other example, I still feel it's a bit stiff in dianling the distance.
John and other shared that this is the 'right' drag for this generation of lenses.
Time will tell if I'm going to peplace the grease again.
Thoughts:
- get different types of grease
- make a more descriptive sequence of photos of the individual steps (next time)
- keep the little parts jars in the right sequence (for sure)
- learn how to take the helicoil apart (there seems to be a trick I do not know yet)
The trick for taking apart the helicoid is to remove the plastic collar on which th edistance scale is engraved along with the silver mounting ring, then turn the helicoid far enough that the helicoid key shows up in the groove on the side which is revealed by removing the collar.
There is one location where next to the groove you can see two approx. 3mm round holes. The key needs to align there. Remove the 2 screws that hold the key by sticking a screwdriver through said holes and applying it to the screws in the only way that makes sense when you see those things.
Mark where the helicoid is when the key is visible and mark which way is up for the key. Then unscrew the helicoid, use a marker to mark wher ethe helicoid parts because it is a multi lead thread.