M5 rangefinder adjustment screw possibly stuck (infinity/horizontal plane)

[Labradieter]

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Hello everybody,

this is my first post and I would like to extend a friendly hello to all of you and also to thank you for your time! 

This thread is not about finding the right screws for adjusting the rangefinder, but rather about one of them not wanting to move. 

The infinity adjustment (horizontal plane) seems to be a tiny bit out of alignment with my M5, and although it probably will not have a significant effect, it still nags me. One factor might be that the brass barrel of the lens I commonly use appears to be quite worn, so that when "freshly" attaching the lens, everything seems to be in order but never goes back to true inifity after the lens is focused to a closer distance and back to infinity, if this makes sense. 

Anyway, the screw inside the roller at the end of the rangefinder arm inside the lens mount does not move. I have tried several straight and angled screwdrivers, even filed one down for better fit, but still: it won't budge. I am afraid of stripping the head of the screw/damaging the arm and wonder:

can or should the eccentric screw at the end of the rangefinder arm be lubricated in any way? Or will this result in unwanted movement/reoccuring maladjustment of the screw? 

When looking straight at the rangefinder arm from the front, there seems to be a small opening in the arm through which I can see the screw, which is why I'm wondering if it's meant to be used for lubrication purposes. What confuses me most though, is that my camera technician has adjusted the rangefinder several times already, and will most probably also have used this screw (although there seem to be other ways after taking the top plate off). Maybe I should ask him if he applied any kind of bonding agent to keep it in place. Although I'd wonder where he should have put it, since it inevitably would come into contact with the roller, inhibiting it from moving freely. 

 

If all of this is too confusing, I can add some pictures later for clarification. 

 

Thank all of you for your time and have a nice day!  

 

Edited April 24, 2019 by Labradieter

[a.noctilux]

Welcome Labradieter,

Some photos may help to understand which screw you refer to.

 

Even if I think that this kind of adjusting precisely needs some precise knowledge and even more, "how to do that with the right tools".

Some days ago, we talked about the "offset from 12h" of M5 roller that can have some trouble with some lenses family.

Which is your lens in use ?

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Edited April 25, 2019 by a.noctilux

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[Labradieter]

Dear a.noctilux,

thank you for taking the time to answer! 

Disclaimers first: I have stopped fiddling with the rangefinder for now, since I don't want to endanger my (as of now) recently calibrated close and mid-ranges, even though the infinity adjustment seems to be out the slightest of bits. 

The lens is a Summicron 50mm f2 version 3, as seen in the M5's brochure and presumably one of the "kit lenses" of the time. I bought them together from the first owner and their years of manufacture are close to each other, so I assume they have spent their whole working life together. 

Although I will add some pictures, the one you attached is very helpful already. The adjustment srew I was referring to can be found when looking at the bottom of the silver roller, sticking out the top end of the lens mount (whereas, as far as I know, horizontal plane / "up-down" alignment of the rangefinder can be adjusted through the hole behind the screw on the front, just below the number "5"). 

But as mentioned, since I have come to the understanding that overzealous infinity adjustments can knock closer distance focussing out of alignment, I have stopped my experimenting for now. Upon my next visit, I might try and get some opinion on on-the-road self-servicing of minor rangefinder misalignments and which tools to use from the camera technician I usually frequent (which I will of course share, if anything comes of it). 

[a.noctilux]

Wise decision.

 

If the mid range and close range is fine with the Summicron 50mm III (yes it's first class Cron, my first Cron also ☺️), I'd not bother with a small

"offset" for far range (in my use, far more than 10 meter = middle aperture or close down ), as near use it can be f/2 or 2.8 mainly.

[chema]

I have a similar problem with my M6. The eccentric screw does not move much more than about 120º and I cannot adjust the infinity.
I have tried with different arm lengths but I don't get a good fit even at 3m. not to infinity.
My questions are:
1.- Is the eccentric screw movement normal or should it have a 360º travel?
2.- If the movement should be 360º, how can I adjust it?

I have not found any photo of the hidden part of the arm once disassembled and so, I do not know if there is any nut that releases the screw from the eccentric.
Sorry for my bad English

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[jerzy]

Eccentric screw shall rotate 360 degrees, there is no lubrication for it. As noctilux wrote care shall be taken when adjusting it, easily the arm can be bent, moves up and does not have correct contact with the cam. The hole in the arm can be used to bent it back, with the help of longer screwdriver. When the screw rotates very hard or does not rotate at all it is better to remove the arm and mobilize the screw  having support for the arm. Before removing arm make a scratch on eccentric shim under the fixing screw, it is for 1m adjustment. When arm is removed you may dip it in WD40, it might help to mobilize the screw. Do not forget to wash the arm in cleaning fluid before installing, WD40 needs to be washed out.

[frame-it]

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1 hour ago, chema said:

I have a similar problem with my M6. The eccentric screw does not move much more than about 120º and I cannot adjust the infinity.
I have tried with different arm lengths but I don't get a good fit even at 3m. not to infinity.
My questions are:
1.- Is the eccentric screw movement normal or should it have a 360º travel?
2.- If the movement should be 360º, how can I adjust it?

I have not found any photo of the hidden part of the arm once disassembled and so, I do not know if there is any nut that releases the screw from the eccentric.
Sorry for my bad English

 

 

http://www.pentax-manuals.com/manuals/service/leica basic repair.pdf

 

[chema]

Thank you all
I have disassembled the arm and straightened the roller shaft. Now the eccentric screw rotates 360º.
When I put the arm back in place, I lost the tension of the spring that holds it forward!
what have I done wrong?,  and, how I can recover this spring?
chema

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[jerzy]

Most probable reason is that the cam which is fixed on the other end of the shaft, within rangefinder, slipped off the rails. This may happen when too much force in axial direction is applied when fixing the screw. You may try following: mount the arm but to not fasten the screw, just that it holds the arm. Insert a small plastic or wooden stick under the arm, rotate the arm forth and back and wit the stick pull the arm down. It could be that the cam will will find its position. If not, you may remove the delimiter which is still on the shaft now and repeat the exercise. If not, than the logo plate needs to be removed (very carefully, not to damage it, it is glued). A screw will be visible in triangle cutout. The screw is for vertical adjustment. When pushing on the screw the rails will move as well and pulling the shaft down shall position it properly. The last one would to remove the top cover to get access to the rails. Both last actions are a bit tricky and need experience, so I would rather leave it to a specialists 

[chema]

Thank you very much Jerzy.

Your help has been decisive. I see you know the M6 very very well
At the first attempt with your first suggestion everything has gone to his place

Now I'm with the calibration, but I know it's a matter of patience and time.

chema