Mamiya six (folding) advance mechanism

[Daire Quinlan]

Ok, so, posted this specific post in a thread in the Medium format forum, but I figure it'll get more traction here. My Folding Mamiya Six wind mechanism is borked.

Mamiya Six IV, seems like a reasonably simple wind mechanism as below, no 6x4.5 option.

What's MEANT to happen is that you wind till the number is at 1, at which point the wind wheel will turn freely, allowing you to load film, then wind it on until you see 1 in the red window (having closed the back obv.). At this point you shoot your first frame, then pull the lever the the left, and the wind wheel should turn enough to advance to '2' and lock, then rinse and repeat.

What happens in my case is that the advance is always locked (for reasons we will see below) with the lever like in this picture, and I have to pull it and hold it to the left to turn the advance wheel. It does *not* operate as it's supposed to do above.

So, quick disassembly, here's everything stripped off the advance mechanism, as seen from the front of the camera. The blue circle is around the spring loaded ratchet that prevents the wind from going backwards, it doesn't prevent it from winding on, just makes a pleasing clicking noise :-D. The red arrow is where the post for the advance lever sits, we'll be putting that back in in the next step.

This is the advance lever inserted back in, it's spring loaded against the small post on the right so that this is its default position. The yellow arrow points to part of it that contacts a toothed wheel which we're going to see in a bit, the RED arrow points to another spiked pawl that, at the moment, fits neatly into the advance gearing, preventing it from turning. There seems to be only one way of putting this together so far so I assume this is correct for now.

This is what this looks like when the lever is pushed to the left ( when looking from the back as in the first picture above ), that pawl disengages the advance gear and I can turn the advance wheel.

This is the next gear inserted, it sits on top of the same shaft that the ratchet sits on (blue arrow above).

And finally this bit. This is a combination of another gear which connects to the other wind gear, and, screwed onto it, a slottedwheel (blue). The yellow arrow points to the end of that advance lever. The numbered dial sits outside the case but attached to this slotted wheel by that offcentre post. Then the wind wheel is screwed into the top. The wind wheel only turns the very bottom gear, which then turns the gear to the left, which in turn turns the gear underneath this slotted wheel, so the slotted wheel and numbered dial make one entire revolution per roll of film.

I'm beginning to suspect that it's the interaction between this toothed wheel and the bit marked in yellow that's the problem. If it's turned in such a way that the yellow bit is held away from the slotted wheel by those extra protrusions then the spikey pawl marked in red in the pictures above does not contact the wind gear and the wheel can be turned. The extra protrusions are another disk underneath the slotted wheel attached to the slotted wheel with a spring, so this is where I think someone took it apart at some point and then screwed up reassembly, unless I'm totally wrong and there isn't a washer missing somewhere or something put in upside down or something.

Anyone disassembled this before ? Even something like pictures of this mechanism with the top off might help :-D

 

[removed account4]

hi daire

i had the same camera ( actually a few of them, different varients ) for a while
and the wind mechanism often times gets wonky from people taking it apart
and not putting it bck together again. i no longer have notes about what i did
or how to CLA the mechanism but i do remember there was a "trick" about loading the film
you so the winder works the way it is supposed to work.
sorry to ask this, but were you loading the film with the frame counter # on 1,
aligning the "start arrow" with the dot closing the back and winding it until it showed 1
in the ruby window and then sliding the double exposure prevention lever so the camera knows
what frame it was ... after sliding the lever and winding to the next frame, it should line up with #2 in the ruby window &c.
i am guessing you probably already knew this ... but just in case ...
if you get it all back together and it still doesn't work right, i'd suggest you send it to a camera repair person who has worked on this camera before.
from my own experience, would suggest you do not send to the guy with "6" in his name, while he may know a lot of things about a lot of folders he knows absolutely
nothing about these mamiyas, and after sending him mine and getting he ruined it and sent it back in worse condition than it was sent to him
( and him billing me for his work ) was the reason i bought another one/s.
antways, i won't pollute your thread with details but if you want to know them i will be happy to PM them to you...
( others have had similar and worse experiences, and others have had wonderful experiences ).

good luck with your camera !
john

 

[Daire Quinlan]

There are a bunch of different variants of these, as you point out. The way this specific version is supposed to work, from talking to someone with the same one, doesn't require that you line up anything when you're spooling the film initially. You ...
1. Make sure the winder knob is at 1. At this position it'll wind endlessly without advancing the numbered dial.
2. Spool the film and wind on a bit
3. Close the back, open the red window, wind until you hit '1'. Close the red window.
4. Shoot your first frame.
5. push the advance lever to the left and release, shouldn't need to be held
6. you now should be able to wind on until the dial reaches '2' at which point it should lock again
7. at this point if you opened the red window it should be at '2'.
8. repeat 5->7 until you shoot 12, at which point if you wind on it should just continue winding, the numbered dial should hit '1' and stop but you should be able to keep winding as at step 1.

 

[tokam]

Hi Daire,

I meant to reply to your last post in the other thread. Sorry for the delay. Your description of the film load and wind on from my post in other thread is correct.

I have heard that Certo6 will not attempt repairs on the wind mechanism on these cameras.

I will have to take the top plate off of my Six in the next day or so to attempt to fix the cloudy rangefinder. I will take a series of pics to hopefully show the relationship of the gears and ratchets on the rewind at various stages - frame 1 before loading, normal shooting of frame 2 - 11, frame 12 just before unloading and after lever is pushed at frame 12 to allow free spool of the wind knob.

At this point I am very reluctant to attempt disassembly of my wind mechanism to investigate the order of the gears on the shaft. From a side on view it is quite complex.

Hope to get back to you with pics tomorrow.

Cheers, Martin

 

[tokam]

Hi Daire,

I may have cracked it. The second wheel down that the ratchet engages is spring loaded. When you slide the lever across to the left, the lower wheel rotates clockwise to lift the pawl from the top frame counter wheel and allow the wind on to advance the film until the next slot in the top wheel.

Unloading the film after frame 12 and loading and winding on to frame 1 are a special case. the slot in the top wheel is shallower which allows the frame counter to stop at frame 1 while the film wind on is free spooling.

It looks like you don't have the spring that drives the second wheel. I haven't disassembled but I suspect it is like a clock spring and it is probably installed under light tension. Movement of the wheel beneath it probably provides on going tension to drive the lower slotted wheel.

Have a look at the pics which show the positions of the two slotted wheels at various stages during film wind on.

 

[SMBooth]

If you get to the point of throwing it in the bin, I would like to discuss if I could purchase the lens of yours to replace the totally ruined one on my M6 folder. Hopefully you fix it.

 

[Daire Quinlan]

@tokam Nice one, thanks. Yeah that little wheel 2nd from the top behaves the same way on my camera as yours i.e. it's spring loaded and does much the same thing. The problem with mine, I was suspicious about and which your pictures confirm, is that even when that pawl ISN'T in one of the slots, the lower part of it (marked with a red arrow in my pictures in the OP) locks the advance wheel. By the looks of things it's ONLY when the pawl slips into one of those slots that the advance is meant to be locked like that. So either 1. the pawl or lower ratchet is bent somehow or 2. someone tried to fix this by putting in a piece from a slightly different Mamiya Six with a similar not-quite-identical dimensions for the advance bits. I'd wager the latter, nothing -looks- bent or out of place. I'll have to compare closely to yours when I get home relative size wise.

Thanks again.

@SMBooth unlikely I'm afraid, the advance isn't a dealbreaker, the film can be advanced using the red window in the absence of a functioning advance, and it is quite a nice shooter


-edit- actually, even comparing the two sets of pictures, the relative sizes of the gearing and slotted wheels and what not look similar, but the actual lever is completely different, mine is slightly longer and unstepped. I'll bet someone substituted it in in an effort to fix an other wise broken advance.

 

[Daire Quinlan]

Hah. So after some judicious filing and a little bit of bending (and some reassembly, testing, disassembly, more filing etc etc) I now have a film advance that works exactly as @tokam describes how it's supposed to work. Basically had to shorten the little spikey pawl (red arrow) by about half a mm or so, and apply a little bit of judicious hammering to the larger arm of it. Tokam, your pictures above and description of how it's supposed to work pretty much crystallised what I had to do to get it in working order, thanks !

D.

 

[tokam]

Well done, Sir. Very happy that I could be of assistance.

I wonder what could have happened to your camera in the past? Perhaps, as you said, someone had attempted repairs with the wrong part.

Life is getting in the way a bit at the moment, (tax time approaching), but I will tackle my rangefinder problem soon.

Cheers, Martin