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Older nikon lens bayonet screws
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PostPosted: Wed Apr 06, 2022 5:47 am    Post subject: Older nikon lens bayonet screws Reply with quote
They can be a bit of a bear to get off, to adapt the aperture ring to a/i.
The following is just personal experience, and what has worked for me. As always, YMMV.

Screwdrivers:

Forget the 1/8" hex drive bit sets. It is awfully difficult to get something that short and small properly hardened and heat treated.
Something with a bit of length to it will better transfer torque to the screw-heads than a short hex bit.

These work well so far, without any flaking or bending:



The screws that give the most trouble are the earlier variant straight slot heads.
They are epoxied in to varying degrees.
The oldest have been drenched in epoxy, and the threaded area for them on the internal lens frame are quite heavily covered.
Sometimes heat from an electronics soldering iron will work to break the epoxy bond.
Sometimes heat is not enough, which means chemical solutions are required.



This seems to work well on epoxy seized screws.



There's a good deal of acetone in it, just by the odours alone.
A little goes a very long way.
This concoction really flows well.
A pipette, or an eyedropper makes applying it far more controllable than the plastic spout on top of the can.
I've found the pipette and it's tiny droplets much easier to work with.
Once the acetone has had 5-10 minutes to work, the screws can be started.
I find it helps a lot to run the screw in a fraction of a turn first, before backing it out.
Heavily epoxied screws will require a bit of run in, and run out before they become removable.
It does take a bit of time, and patience has the pay-off.



-D.S.


PostPosted: Wed Apr 06, 2022 9:16 am    Post subject: Re: Older nikon lens bayonet screws Reply with quote
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Doc Sharptail wrote:
They can be a bit of a bear to get off, to adapt the aperture ring to a/i.
The following is just personal experience, and what has worked for me. As always, YMMV.

Screwdrivers:

Forget the 1/8" hex drive bit sets. It is awfully difficult to get something that short and small properly hardened and heat treated.
Something with a bit of length to it will better transfer torque to the screw-heads than a short hex bit.

These work well so far, without any flaking or bending:


Mastercraft, I have seen them recommended a few times before; must try them one day.

Vessel (Japan) and Starrett (USA/UK) are also good premium options, and Engineer (Japan) is a good budget option.

No experience with Wera (Germany) precision screwdrivers, but their full-size counterparts are very good.

Doc Sharptail wrote:
The screws that give the most trouble are the earlier variant straight slot heads.
They are epoxied in to varying degrees.
The oldest have been drenched in epoxy, and the threaded area for them on the internal lens frame are quite heavily covered.
Sometimes heat from an electronics soldering iron will work to break the epoxy bond.
Sometimes heat is not enough, which means chemical solutions are required.



This seems to work well on epoxy seized screws.



There's a good deal of acetone in it, just by the odours alone.


Going by the constituents, I could make that myself apart from their secret "Petroleum Distillates" catch-all Wink (Whilst not technically a petroleum distillate I believe, I wonder if that also contains dichloromethane/methylene chloride...)


For me, the most problematic are the composite construction zoom cams on the mid-generation Minolta MD zooms; Minolta decided to epoxy those in, but there is no space to apply a solvent, the heavy aluminium blocks they are screwed into divert the heat from a soldering iron too quickly, and heating the whole block is a no-no as the cemented lens groups are still inside the blocks. In the service manual those whole slotted compound zoom cylinders/mechanism + mounted zoom group lenses are listed as "NO SUPPLY" and "DO NOT DISASSEMBLE", indicating they were not really designed to be serviceable.


PostPosted: Wed Apr 06, 2022 11:10 am    Post subject: Reply with quote
"Mastercraft" is the store brand name of Canadian Tire stores.
It's tools are very near in quality to what was offered by Sears "Craftsman" tools, which were very good for their time.
I still have a few craftsman tools around here- mostly screwdrivers and wrenches.
Their socket sets were very highly desirable at one time.
The set pictured above is in the mid-price zone.
Their really high quality stuff is kept under store lock and key...

-D.S.
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