Fundamentals: Helicoids, etc. (3/3)

Now that we have talked about screws and lubrication, we can finally start with the actual skills for taking apart and re-assembling classic Nikkors. Most of the things that I will mention here are based on common sense. Please refer to my previous blog posts because there are many important things that are mentioned there that will not be repeated here.

I will update this blog post from time to time.

Workplace:

Be sure that you are working on a well ventilated place since the fumes are can potentially be toxic. Disassemble your lens on top of a soft, clean cloth such as a towel to prevent anything tiny such as screws to bounce off your table. That same towel will also prevent any serious damage to your glass when you have accidentally dropped one.

You would also like to buy those pill organisers from the pharmacy. They are cheap, small and perfectly suited for organising screws and parts as you disassemble your lens. What I simply do is I group all of the screws from the exterior to one section and all of the screws and fittings from the interior into another. This will make things a lot simpler for me when it’s time to re-assemble my lens. Finally, put your lubricants away from your work area so that you will not accidentally leave any part oily.

You may also want to put a ground on your table so that you discharge any static electricity. This will keep you from ruining any sensitive electronics found in modern lenses.

Rest Position:

Before you begin taking apart your old Nikkor, set the lens to it’s rest pose first by turning the focus to infinity. For zoom lenses, set it to the closest distance or the furthest one depending on which lens you are working. For the aperture rings, I usually set it to f/8 or to whatever f-stop is considered the middle number.

Taking Notes:

Not every Nikkor lens variety are ever made the same. There will be times when even seemingly similar lenses will have no interchangeable parts. In the case of the Nikkor-S 5cm f/2 and the Nikkor-S the 50mm f/2, only the 2 outer barrels is interchangeable. So do not assume that if you opened a lens, the other one will be the same. There will always be some individual production differences unique to a specific lens like the placement of the focusing spacers, calibration screws, spacers, etc that are secured in place differently.

One way to take note of something is to take pictures of it for reference, in different angles as well if you need to. Back in the days at the watch repair shop, our technicians would draw and sketch each critical step so they will have a reference to go back to when they need to re-assemble the watch. We have notebooks full of sketches for that and we kept them very well for future references.

Today in 2016, almost all mobile phones have good cameras built in them. Taking notes today is as simple as taking multiple pictures of every step of the disassembly.

IMG_1680

The picture above shows an example of what we have discussed in actual practice. The helicoid alignment is very critical and before taking it apart, it is important that we take note of how it looks like before we dismantle it. Getting it back together in the wrong position will result in a lens that will not focus properly.

A perfect example of something that you would need to take pictures of in different angles is the aperture assembly to note how things look like and also to note the position of different parts in relation to each other.

Another good way for taking notes is my marking. Some people prefer the use of a lead pencil to mark any key positions because lead pencils will not leave any permanent marks. I prefer to simply scribe marks on the surface of the part/s with sharp tool. This will leave permanent marks on the lens so only scribe the marks on the inside of the lens where it will not be seen. What I usually do is scribe lines, arrows and small marks like number or a the triangle.

This practice is fairly common and even brand new lenses that came out of the factory have them. This will also indicate that a lens has been serviced by another person prior to you opening it. They are permanent footprints but necessary for future reference when you need to re-assemble the lens.

The most common steps or places to mark are:

IMG_1680The infinity position when the lens is set to infinity. I mark the helicoids & lens body so that a line goes through all of them. This is my reference line to check if I re-assembled my lens properly.

IMG_1682You should definitely mark where the helicoids separate. Forgetting to do this will cost you many painful hours trying to figure out how to get your helicoids back together properly. Mark a line against a common reference point like the infinity mark of whatever it is connected to.

IMG_1445The rest position of the helicoid keys and helicoid stops are optional but it can come it handy later on to check if things are all aligned.

IMG_1531Any adjustment screws or fittings that you plan on removing. In general, these things should never be touched.

IMG_1279In general, you should mark anything you think will be important for re-assembly.

This video should help you get started really quick, please study how I did it in this video and try to make sense of what I was doing while referring to the notes above.

Avoid These:

For a general lens overhaul, you should dismantle everything that you can as long that is not related to the optical block unless the optical block also has helicoids like in the case of lenses with CRC floating elements. Optical blocks are considered separate from the focusing unit and these units are built to very precise tolerances so we would rather avoid working on them unless you really need to like in the case of lens cleaning due to fungus or oil on the aperture blades so do not touch them if you only want to replace the grease in your helicoids and clean up the mechanical part of the lens.

The parts that you should avoid messing with are:

IMG_1452Leave any ball bearings and their assembly alone. You do not want to pick up any of the tiny balls up do you? Opening up one by removing the copper ring that secures them will send them flying to any direction!

IMG_1569Also leave any springs alone. Trying to remove or play with one will send it flying across the room. Instead, secure them by applying nail polish to the ends of the spring where they are secured to any part of the lens.

IMG_1593Any part that you have no clue on how to open them up. Some parts of the lens are glued securely together with pitch (a black resin), glue or clamped together by a metal ring. Attempting to force-open any of them with brute force will just result in permanently broken assembly.

IMG_1531Do not even think of attempting to remove or modifying any screws or keys that is involved involved in calibration and alignment unless you have to. If you do not get these right after you have undone them then your lens will not focus properly and you will waste a lot of time figuring out how things should be.

Dismantling:

Dismantling an old lens may sound easy, watching the pros work will even make you believe that as well. In reality things are rarely that easy and the chance for a failed project due to faulty dismantling is high. To avoid this, there are some pointers that you should follow:

IMG_1164A grippy rubber glove is essential for dismantling. Not only do these help you by adding more friction to your grip, they also serve as protection for your hands from abrasion and cuts.

IMG_1661Some parts are held together by a weak adhesive like lacquer. This practice is common on the optical assembly to prevent it from misaligning or keep it from unthreading due to vibration or other movement. If something will not unscrew by using your barehand or with a grippy rubber glove, just put a tiny amount of acetone into the thread by using a pair of tweezers. Leave it for a few minutes and try again, if it still does not budge then repeat the step again until it does. If this does not work then give the acetone more time to work on the lacquer. Just apply the acetone to one spot anywhere on the thread and let capillary action will take the acetone into the rest of the thread. Do not put too much as it might dissolve anything that you do not intend to dissolve in the first place.

IMG_1662In relation to the previous picture, there will be times when you will find a hole in some of the metal rings and fittings. These holes are used to refill lubricants as well as to apply any adhesives to prevent these from getting undone accidentally. Dropping your acetone here is a great idea as this will make sure that the acetone will get to every corner of the thread. A strong alternative to acetone is butanol (MEK).

IMG_1153Always use the proper tool for the job. Using the wrong tools for the job will only result in failure. I have been in that situation that is why I am doing all this so that you will not get into the same situation that I had when I was first starting.

IMG_1431Screws on the bayonet mount can be a pain. Plenty of Loctite was used to lock them in place. Loctite responds to heat so heating that nasty & tight screw with a soldering iron until it is too hot to touch will help but to heat things faster, I use a miniature butane torch. Another way to undo a tight screw is putting acetone into the screw until it the acetone works on whatever substance they used to lock it.

Fortunately, I do not have to do any of this these days. if you can recall my previous blog posts, I have mentioned that Vessel brand screwdrivers are the best for the job and using a long-shafted one is more then enough to safely undo these annoying screws.

I also use a Wiha magnetiser to magnetise all of my screwdrivers so that the screws will not accidentally drop anywhere when I unscrew them. It will also make the task of placing the screws to their holes easier.

IMG_1154Use a lens sucker to pull out any glass elements that are inside of a barrel. Simply trusting gravity to do the work for you is dangerous because doing it that way might scratch the edges of the your lens element and lead to a chipped edge.

In relation to removing the lens elements, make sure to always work with the lens facing up specially when you are removing the small screws that hold the optical block to the focusing helicoid. The optical block is heavy and removing the screws that hold it will send it free-falling to the floor with the help of it’s own weight!

IMG_1615Some parts are held together by scotch tape. Make sure that you mark any place for reference when you rejoin these as well as clean the old adhesive marks left behind by the old tape by using lighter fluid or benzine.

IMG_1139

Use extra care when removing the rubber grips on your lenses. The zooms and longer focal lengths will have wider rubber grips and these tear rather easily. Vintage rubber can become brittle due to age and may break or tear anywhere if they are not handled carefully.

IMG_1611The tiny set screws are usually 1mm headless screws that hold the front lens elements in place. They are also used to secure the front barrel and other internal parts. I hate these because they always have a tendency to disappear if dropped on the floor and are easily damaged because they are usually brittle. Loosen them enough so that you can remove whatever it is securing and just secure them back in place by screwing them back in.

IMG_1065For lenses with 2 helicoid keys, always remember which key goes to which slot. They are broken-in together so mismatching them will only result in a rough focusing feel. Just mark them.

IMG_1518

Screws that are held by red lacquer require no prior steps like the acetone treatment for unscrewing them. These serve more as a seal of some kind to find out if a lens has been tampered rather than serve as an adhesive. There will be times when leaving the marks there is good because you can always use them as reference when re-assembling.

to be continued…

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