Taking apart Cooke Knuckler

[dap]

Howdy,

I recently got my hands on a user condition series IIB cooke knuckler triplet. There is some haze on the backside of the front element and I would like to clean it. The front and middle elements unscrew as one big air spaced group and for the life of me I can't figure out how to remove the front element from this group. The center/middle lens looks like it is machined into the rear of this group so I'm not going to be able to get to the front element from the backside. As far as the front element is concerned I looks like it is either A) held in by the front name-plate ring (the front rim of my lens is bent so if this is the case I'm f**ked) or B) There are some well hidden threads holding the two elements into the front group and I'm totally missing them (maybe seized up due to age). Have any of you stripped one of these apart to clean the individual elements? If so, any helpful hints?

At this point it looks like I'll just bite the bullet and send it off to Focal Point to have it cleaned (or more likely just use it with the haze), but if it is possible to separate the front and middle elements without screwing it up I'd much rather do it myself and save some cash.

Any help would be appreciated.

Thanks

[Steven Tribe]

AFAIK there are many construction variations of the IIB through the decades.
Serial number/photos would be helpful. I don't recall a "name rim" thread being the clue to any Cooke dismantling!
There must be knowledge and experience - as triplets were designed for cleaning without the use of special tools.

[eddie]

we need photos of the front to know which you have......without seeing it no one can help.

some need a "lens wrench" some come off with the hood. some the hood comes off and then the glass is unscrewed.

i have two series IIE right now and they both "look" the same and both come apart differently!

[dap]

Here are some pics of the front group containing the front and middle elements...hopefully they will help (they are pretty sh*tty snaps so maybe not :o)

The only possible area I can see where additional threads could be hiding would be either above or below the knurled aperture ring. There is what feels like a distinct sliver of a groove between the hood and the knurled/brassed aperture ring, but then again it could just be a machining mark (if there are threads there they are seized). 7757967579775798

[Steven Tribe]

I am a little bit loathe to give advice.
But I can't quite quite place the parts on this. Does the soft handle move the front section - composing both the middle and front lens - forward as a complete unit?
The distance between elements is very crucial on triplet designs and the mounting threads are not visable at all when the cell is completely screwed in. So it is difficult to tell what is a single brass turning and what (although it looks like a single turning!) are two parts joined by a thread!

[dap]

I am a little bit loathe to give advice.
But I can't quite quite place the parts on this. Does the soft handle move the front section - composing both the middle and front lens - forward as a complete unit?
The distance between elements is very crucial on triplet designs and the mounting threads are not visable at all when the cell is completely screwed in. So it is difficult to tell what is a single brass turning and what (although it looks like a single turning!) are two parts joined by a thread!

The cell that is shown it the photo appears to be one turning (unless there are some hidden threads somewhere that allows it to separate). The cell is composed of the front and middle element and the whole unit screws (via the exposed threads that can be seen on the cell) into a rotating sleeve within the barrel that operates the aperture. When the soft focus knuckle is rotated the whole front cell/aperture assembly moves forward and backward.

Ive taken apart plenty of lenses but this one has me stumped. upon further inspection I don't think the front nameplate ring is the answer due to the fact that the threads leading to the nameplate are not continuous (unless it is pressed in). The only place that even remotely looks like it could be hiding some threads to unscrew the elements would be either directly above or below the thin brassed/knurled aperture ring (between the hood and the aperture numbers). The hood did get a nice ding sometime during its life...maybe that was enough to seize the threads if there are any there.

BTW - one question for you seeing as though you sound like you have handled these before. Out of curiosity, do most of these have clickstops for the soft focus adjustment (one detent at every softness setting)? The only other one I've ever handled was years ago at a camera show and I remember it just being a smooth adjustment from sharp to full soft setting...maybe just more variation over the years.

Thanks

[Steven Tribe]

The late IIe (post war coated) certainly does have click stop motion for stops - but I don't think the earlier designed models did.
I don't believe the threads are damaged by the hood ding. Years of non-use (meaning - no internal cleaning) means that these tight fit threads are difficult to get started. There is no sign that this lens has been in a damp environment, so verdigris bonding in the threads will not be an issue.
There are lots of threads (written!) on this. It is just a matter of holding 2 likely parts and turning with or without friction/mechanical assistance. Two people (four hands) can exert more than double the torque that 1 person can.
To me, it looks like you will double your chance by trying with the lens hood and the rear most (but narrow) surface which is the central -ve lens cell. Thus you are trying to loosen 2 cells at the same time and one of these will be "easier" than the other.

[eddie]

most often knucklers have click stop feel on the SF. the non knuckler ones generally do not have click stops, and they generally have more movement capabilities in the SF adjustment (ie. they turn more) .

i have more info coming as it uploads.

there are no screws holding the groups in BTW.

all the knucklers potentially come apart in different ways. i have seen like 4-5 different variations. i will post more info after the upload finishes.

thanks

eddie

[dap]

To all of you who respoded - a hearty thanks. I managed to remove the front element. It separates at the hood/knurled ring junction. The surface area of the two mating surfaces are rather large which creates a LOT of friction. The threads on my lens were not seized at all - it just took some significant force to get it started. I ended up having to make two wooden clamp type wrenches to break it free. I'll upload some pics of the lens/wrenches for future reference...in case anybody comes across the same problem.

[eddie]

well, i got distracted......sorry. here is the video anyway:


http://www.youtube.com/watch?v=ZNiCIw743qA

[Steven Tribe]

Well done Eddie!
Just two weeks too late for my IIe work but I guessed the right thread!
As our OP mentioned, these can be problematic to turn - even when the threads are in good condition.

[ederphoto]

Great post by Eddy Gunks ! Perhaps one of you can direct me on how to remove the inner tube so i can get access to the knucklers screws .They need tightening . Based on Eddy's video i was able to unscrew the front element .The whole front assembly comes off along with the black ring . The knuckler screws sit between the outer and inner barrel as seen in the picture .Any help would be appreciated . Probably Louis can help with that ! Thank's

[Steven Tribe]

There are two uncomplicated screws - I'll check old photos and perhaps even threads here.

Some kind of "loctite" woule be a good idea so it doesn't loosen up again in 60 years.

[ederphoto]

Thank's Steve ! I have the loctite ready ! I just need to figure out how to remove that inner barrel to access the knuckler screws .




There are two uncomplicated screws - I'll check old photos and perhaps even threads here.

Some kind of "loctite" woule be a good idea so it doesn't loosen up again in 60 years.

[Steven Tribe]

I remember the outer barrel comes off by itself. There is a ball bearing ( a slight position marker!) that can get lost.

[Steven Tribe]

I don't have a set of photos from my servicing.
So I have just taken it out and played with it. I can understand why there is no "documentation"!
When the lens hood assembly is taken off, the brass section just pulls off!

But mine is the last 2E model and is cleaner to look at than the two models shown by Eddie in his videos.

I have pulled this knuckler ring about a centimeter out to show the cut track which drives the lens forward.

[ederphoto]

Thank's Steve ! Mine is a series VI but i believe your information to valuable . I will examine mine to see if the outside tube comes off like yours. Thank's for taking the time to help .

[Steven Tribe]

I love an excuse to "play" with lenses!

[ederphoto]

Success Steve ! Based on your information i was able to completely disassemble the lens down to the aperture blades . I tightened the two screws and the lens is ready for another 60 or 70 years of use ! It works perfectly now !

[ederphoto]

Some shots , the last one is the lens reassembled :