Rolex Val 727

Discussion in 'Wrist Watches' started by Pioneer, May 20, 2020.

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  1. Pioneer

    Pioneer Registered User

    Jun 5, 2015
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    I have a very long overdue-for-service Rolex 727 movement that the chrono has issues on.

    This movement has been stored in a safety dep. box and not touched since the early 80's.

    It is very clean, it winds and runs, but the chrono does not function. When the chrono is started, the balance wheel slowly comes to a stop. The barrel functions seem normal, and the chrono clutch mechanism engages normally with a click when the start button is pressed. When the chrono is stopped, the balance wheel movement immediately comes back. The seconds register on the face turns normally.

    The Chrono reset mechanism does not function. The reset simply will not 'push' with normal effort. The chrono reset brake pin by the barrel seems to be blocking the mechanism, and not releasing the reset function. If I very carefully move it a hair, I can push the reset, and the arms will engage the heart cams normally and resets everything to zero.

    What else goes on for the reset function? I do not know if it had issues when it was stored or not. My dad was a hobby enthusiast way back in the day.

    Rolex experts, could lack of service/lubrication have this movement so stiff that the chrono won't run at all? The start/stop functions are crisp and snappy. The stuck reset concerns me that it may have major issues. Thoughts?
     
  2. Tomxhar

    Tomxhar Registered User

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    Needs a new mainspring and a full service.
    A shame to leave in a bank vault.
    Don't send it to Rolex though.
     
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  3. gmorse

    gmorse Registered User
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    Hi Pioneer,

    I'm not familiar with this Rolex calibre, and I don't know whether it's a pillar wheel or multiple cam design, but in general, when the reset button is pressed, the brake is taken off the centre seconds wheel a fraction before the reset hammer drops onto the heart-shaped cam to return the hand to zero.

    The problem with the chrono stopping the watch may be related to the brake not disengaging fully when you start it, or it may be something to do with the engagement of the intermediate wheel with the centre seconds wheel; this is normally adjustable, but if it's been adjusted wrongly or just become dirty, the pressure can stop the movement. The teeth on these wheels are very fine, and a little dirt can go a long way!

    Regards,

    Graham
     
  4. Chris Radek

    Chris Radek Registered User
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    It's a Valjoux 72, which is great, because anyone competent to service vintage chronographs can find any needed parts.
     
  5. gmorse

    gmorse Registered User
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    Hi Chris,

    Thanks, that does indeed make it easier.

    Regards,

    Graham
     
  6. Pioneer

    Pioneer Registered User

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    Thanks for the replies. Yes, the 727 is basically a Valjoux 726 that Rolex modified to 21,600 bph. Breguet overcoil hairspring & microstella balance.

    I'm sure it is down on power due to dried grease. I have not attempted to put a full wind on it.

    I am trying to determine basis of the reset issue. On other similar Valjoux movements that I have worked on, the reset seems to have some effort, but then it 'snaps' and resets. It seems this one is sticking and whatever mechanism parts that 'snap' will not release. As I mentioned earlier, if I very slightly move the centre wheel brake arm against its spring, it allows the pin on the brake arm near the barrel to quit blocking the reset hammer and let it be pushed and everything will reset. Can anyone help with a description of the events that release/actuate the reset hammer? Is it supposed to slide that blocking pin over the corner on the reset hammer by the force from the pusher, thus allowing the 'snap' or does another mechanism release it?
     
  7. Pioneer

    Pioneer Registered User

    Jun 5, 2015
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    What I need to figure out, is what happens when the reset is pressed that makes this vertical pins move out of the way to let the reset hammer swing down. If I manually move it about .015" it will allow the reset to be pushed and the reset mechanism then works normally.

    (Note: this pic is not my movement, but a random pic of the same caliber)

    Also, moderators, please move to watch repair if that would be a better spot for this post- thanks.

    727 Chrono.jpg
     
  8. Tomxhar

    Tomxhar Registered User

    Sep 2, 2019
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    Possibly the crown wheel position needs resetting?
     
  9. Pioneer

    Pioneer Registered User

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    The column wheel will just turn one way, like a rachet, and move the levers through their motions. I do not think it can be adjusted for 'timing'- I may be wrong. I do not know if it has an eccentric, or lateral adjustment.

    I need that emsembl-o-graf reference that has tech/ adjustment info on these chronos.

    I cannot find a download for it that is valid. Looks like I will just have have to order it, and hope there is some good ref. material in it.

    Does anyone on here happen to have the volume that deals with Valjoux chrono movements?
     
  10. gmorse

    gmorse Registered User
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    Hi Pioneer,

    I don't think the column wheel is adjustable in the way you describe, it does just move the various levers in sequence. If something is happening out of sequence there may be an eccentric wrongly set which controls the travel of a lever elsewhere, but that's separate from the column wheel. Could you show a picture of your actual movement, please?

    A tool which I made and I've found useful when examining chronos is a slotted brass rod with which to slowly turn the column wheel in a controlled way to check on the sequencing. Just using the pushers means that everything happens too quickly to observe properly.

    Chrono Column Wheel Tool.JPG

    Regards,

    Graham
     
  11. Pioneer

    Pioneer Registered User

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    Thanks, here are a couple of pics of my actual movement. One with movement running and chrono disengaged, the other is with chrono engaged and movement brought to a stop.

    I was struggling getting a decent pic- thus the reason for the stock movement photo.

    And, the tool I whipped up to advance the column wheel.

    IMG_20200522_180656508~2.jpg IMG_20200522_182356902~2.jpg IMG_20200522_190113184~2.jpg
     
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  12. Pioneer

    Pioneer Registered User

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    I definitely like the design of your
    column wheel tool better. I'll make one of that design.

    I'm looking for a stock image of the brake arm end surface profile where it contacts the outer circumference of the column wheel to know what to look for for wear.

    I know my father used the chrono on occasion, but I would not think eough to 'wear it out'. The watch does have the chrono start/stop pusher button missing. The splined case tube and the pusher plunger are present and function normally. Upon examining with a loupe, the actual threaded end of the pusher plunger is broken off. I have to press it with my fingernail, but it gets the full stroke on the mechanism.
    I have considered that whatever force broke the plunger cap off could have damaged the mechanism. However, the reset is what is not working, and that plunger and cap are completely intact.

    My father had quit wearing the watch and put it away when the pusher cap was lost. He got another watch to replace it. He did quite a bit of scuba diving with his watches and was concerned about the water integrity after the pusher cap was lost. The watch's crystal has a hairline crack as well.

    Anyhow, that is how the watch came to be stored for so long. I was a teenager back then. My mother passed recently, and I inherited the watch.

    I do not intend to ever sell the watch or concern myself about its value. It's a sentimental heirloom to wear on occasions and pass on to my son. I do not want to send it to R and lose half the original parts to service. I have a new pusher assembly from Ofrei that I will refit the broken one with.
     
  13. gmorse

    gmorse Registered User
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    Hi Pioneer,

    The curve on the business end of the brake lever should match the chrono wheel quite closely, and I don't think it should show any wear, since it should just bring the wheel to an instant halt and the forces involved are very small.

    The problem of the chrono stopping the watch when it's engaged could be connected with the depth of the transmission wheel with the chrono wheel. This is governed by the eccentric screw marked in red, and is sometimes found to have been 'adjusted'. The engagement should be deep enough to drive the centre wheel positively but only just.

    IMG_20200522_182356902~2_edit.jpg

    If you can find a copy at a reasonable price, the book "The Chronograph, its Mechanism and Repair" by B. Humbert is very useful. Another good source of information is Doug Shuman, (dshumans on this board), who's very knowledgeable on complications, but doesn't drop by very often.

    Regards,

    Graham
     
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  14. Pioneer

    Pioneer Registered User

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    Thank you for those references. I feel like the 'braking end' of the arm where it contacts the seconds wheel is in proper order.
    When I start the chrono, I can see it lift clear from the wheel ever so slightly, releasing the brake. When the chrono is stopped, it drops back down to the wheel to 'freeze' it- as I understand is correct.

    The engagement of the driver wheel to the seconds wheel could possibly be too tight as you suggest, keeping the chrono from running and stopping the movement. I will investigate that.

    I was able to find some detailed
    material on that adjustment from B. Humbert in a technical discussion. I will try to find a copy of his book.

    What continues to snafu me is the blocking of the reset hammer by that pin circled in red in the pic above when the chrono is stopped and I go to push the reset pusher. I cannot see anything else blocking the reset action, and I do not understand what setting, or function will move that pin aside enough to let the reset hammer past it to operate.

    IMG_20200522_180656508~3.jpg
     
  15. gmorse

    gmorse Registered User
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    Hi Pioneer,

    As you see, the mechanism in question is mostly hidden underneath the flyback hammers, and without the movement in hand, (and in the absence of pictures when partially dismantled), it's hard to say what's going on under there. What I do notice is what appears to be oil on the hammers, which there shouldn't be.

    IMG_20200522_182356902~2_edit2.jpg

    I'll see if I can find anything specific on this in Humbert.

    Regards,

    Graham
     
  16. Pioneer

    Pioneer Registered User

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    Thank you Graham- I appreciate your help.

    The way I am seeing it, is that the blocking pin on that seconds wheel brake arm is staying in the position it should be in during 'chrono running' state- to 'block' the reset mechanism from being pushed inadvertantly (or by someone who doesn't know better).

    When the chrono running is stopped, the brake arm, and consequently that pin on it, should be moved, or left
    in a position to allow the reset function.

    Something there is not happening, or preventing that from happening.

    But, that is a fixed arm, and the braking action on the far end of the arm on the seconds wheel seems to be happening correctly. I am not sure how far it should lift from the wheel though. In order for me to allow the reset hammer to move past that pin I have to manually move that braking arm about ~.015" to get the pin to clear the edge on the reset hammer. The face of the braking arm that touches the outer circumference of the column wheel is the the only thing I see that determines those positions.
     
  17. gmorse

    gmorse Registered User
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    Hi Pioneer,

    Please see your conversation inbox.

    Regards,

    Graham
     
  18. Pioneer

    Pioneer Registered User

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    I wonder if a suitably hard impact to an unscrewed reset pusher could have slightly bent the fixed pin that the reset hammer pivot point is located on. That is one thing I will check soon. That could change the relation of the pin to the nose on that hammer by some degree.

    I know my dad wore this watch for many years. I never realized just how much he beat the watch up. Judging from the cracked crystal, scrathes on the case,
    both pushers have already been changed at least once (sadly, neither are the correct original pushers) I'd say he was pretty rough on it considering. I know it was serviced by R at least twice because my mother remembered the services. I'm sure she kept the paperwork, she was very meticulous. I just have not come across it yet in her files.

    I just ordered a CD with the entire
    Ensembl-O-Graf 29 volume set
    on chronometer calibers. I understand from reading about those that several of them cover Valjoux specific calibers. This ref. would be a bit old to have the actual 726/727, but my understanding is that the chrono on the 726/727 shares design/parts with ealier Valjoux calibers.
     
  19. Jeff Hess

    Jeff Hess Moderator
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    curious as to the color of the chrono wheels. It must be a pre Daytona? I have owned thousands of these and I know opinions are varied and passionate. But if it were me, this would go straight to Rolex.It may be a family heirloom with no intention of selling, but why take the chance of a watchmaker replacing with non rolex parts (not a sin with most watches but a mortal sin with rolex) or makign a part (Again, normal watchmaking but not accepted with Rolex). ? Get it to Rolex in nyc or Dallas or their vintage division in Litiz. It will be done right and you will have the most valuable "repair papers" with it.
     
  20. Pioneer

    Pioneer Registered User

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    That is very solid advice. Yes, it is an early pre-daytona cosmograph. I am only in the process of determining the condition, and what is wrong, or more pointedly 'what happened' to cause the issues I am seeing.

    I have determined that the flyback, or reset hammer was ever so slightly contacting the seconds runner wheel preventing it from running. Once that contact was relieved, the chrono now runs like a champ. The cause appears to be the pin that the flyback hammer pivots on is ever so slightly bent in the direction of the pusher force. Most likely an overzealous push or impact. Once that is flyback hammer alignment is sorted then a full normal service should put
    it right.
     
  21. Jeff Hess

    Jeff Hess Moderator
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    great watch! goood luck with it! Does it have a red and blue dial or standard black lettering?
     

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