Wildly erratic beat behaviour, Brocot escapement

Discussion in 'Clock Repair' started by Peter Planapo, Jun 12, 2019.

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  1. Peter Planapo

    Peter Planapo Registered User

    Mar 23, 2019
    71
    2
    8
    Male
    Country Flag:
    Hi all,

    I'm scratching my head about two clocks which both have internal Brocot escapements with steel (not agate) pallets.

    They are both runners.

    What's confusing me is the beat. Correct me if I'm wrong but I believe Brocots can be set in beat simply by giving the pendulum a full swing. In beat or not, at least I would hope that if there's a beat error it would be constant.

    These two clocks couldn't be more different outside, but the movements are pretty similar, one being made by Richard & Cie, Paris and the other unmarked but of the same era. I call it the Francois I, because the case is emblazoned with a crowned fire-breathing salamander and fleurs-de-lys.

    Using the Windows Watch-O-Scope app, I've recorded the beats of both clocks. FYI the x-scale on the graphs is 150s full scale and the y-scale is 0.5ms per division.

    The Richard & Cie (first pic) isn't at all bad, it's in beat most of the time with a short part of each cycle mildly out of beat. I am not worried about this clock. It keeps time very well. I include it only as a reference since it's my only other internal Brocot.

    The Francois's beat (second pic) is all over the place. Basically it's never in beat but for half the escapement cycle the ticks are faster than the tocks, and the other half the tocks are faster than the ticks. Well OK, "faster" is the wrong word as the rate is constant, but half the cycle is out of beat one way, then the beats cross over and the second half of the cycle is out of beat the other way. The beat error cycles from +14ms to -8ms for a 22ms total, and this stays pretty constant even with manually setting the beat, which of course isn't really possible.

    What's wrong, does it matter, and how can I fix it? I surmise maybe a bent escapement arbor, or pivot, or a bent escapement wheel? Or should the teeth be "topped" as a friend suggested?

    I'm sure it's a problem many of you experienced members will be familiar with, so many thanks for any guidance you can give me.

    Peter

    Richard&Cie.png Francois I.png
     
  2. Willie X

    Willie X Registered User

    Feb 9, 2008
    11,294
    507
    113
    These clocks have delicately made escape wheels which often suffer bent/damaged teeth.

    The 'beat' has to be adjusted manually.

    Willie X
     
  3. bruce linde

    bruce linde Technical Admin
    NAWCC Member

    Nov 13, 2011
    5,061
    388
    83
    oakland, ca.
    Country Flag:
    Region Flag:
    a friend gave me a binocular microscope a while back... it changed (literally) how i look at things... especially escape wheel teeth.

    you need to look at the escape wheel teeth under magnification... the more the better.

    you also don't say whether you've been through the clocks and serviced them. if all pivots are true and have been burnished and all pivot holes checked for wear and/or bushed that would give you a baseline.

    the escape wheel could be worn, or one of its pivot holes could be worn and allowing it to shift slightly so the beat is thrown off...

    random thoughts, hope they help.
     
  4. jmclaugh

    jmclaugh Registered User

    Jun 1, 2006
    4,137
    62
    48
    Devon
    Country Flag:
    Region Flag:
    I have a clock with a pendule de Paris movement and an internal Brocot escapement and it is just as finicky to get in beat as a recoil one, in my experience if they aren't in beat they stop.
     
  5. shutterbug

    shutterbug Moderator
    NAWCC Member

    Oct 19, 2005
    39,689
    534
    113
    Male
    Self employed interpreter/clock repairer
    Iowa
    Country Flag:
    Region Flag:
    It would be unusual to find a Brocot with an auto-beat correction. As Willie said, you need to set the beat manually.
     
  6. Peter Planapo

    Peter Planapo Registered User

    Mar 23, 2019
    71
    2
    8
    Male
    Country Flag:
    Many thanks as always for your generosity in taking time to help.

    Indeed, I haven't overhauled this clock and apart from cleaning and oiling it's just as I got it. One day I'll have the courage to split the plates and do a proper job, learning how to bush and burnish and such.

    I totally agree about stereo microscopes; every clock and watch collector should have one. Since one of my other hobbies is microscopy and microscopes, I'm well equipped in that department.

    Regarding the self-setting nature of Brocots, may I quote the late Mr W.J.Gazeley (Clock and Watch Escapements, 1956)?

    Clocks with the Brocot escapement are what is called self-setting,
    i.e. by giving the pendulums a big swing they will put themselves in beat.
    The crutch is screwed on to the pallet arbor instead of being a fixture as in most clocks.
    The pendulum with a big swing forces the pallet pads to bank against the band of the
    'scape wheel, continuing this action until the vibration eases off.
    As the pallet banks on the wheel the crutch carries on and banks on each side until it
    eventually settles down with the crutch equidistant, the escapement then being in beat.


    It works for me, but only with Brocots. I don't have that many, just four. I just give one full swing and when the amplitude is settled, within a minute or two, it's in beat to within 2 or 3 milliseconds. I've experimented by chocking the clock out of level, and the procedure still works, also by deliberately putting it out of beat and making the swing, when it puts itself in beat again. Recoils of course need a lot of trial and error to get that close.

    Could it be in view of your replies that there are differing Brocot or crutch designs, some being auto-correcting and others not? I mean, I'm a newbie here and you guys are vastly experienced in comparison, so I'm not about to tell anyone they're wrong :), but truly my Brocots are self-setting.

    Regarding the rogue clock in question, not only does it run but it keeps good time, within a few seconds a day, So I'm torn between overhauling it, and "if it ain't broke, don't fix it". I'd say it was testament to the Brocot design, that despite this erratic beat behaviour, the running and timekeeping are pretty well unaffected.
     
  7. shutterbug

    shutterbug Moderator
    NAWCC Member

    Oct 19, 2005
    39,689
    534
    113
    Male
    Self employed interpreter/clock repairer
    Iowa
    Country Flag:
    Region Flag:
    The Brocots are pretty sensitive to harsh movements, so I'm surprised to see that in print. But we're never too old to learn :)
     
  8. Willie X

    Willie X Registered User

    Feb 9, 2008
    11,294
    507
    113
    That probably shouldn't be repeated. The beat, on these clocks is not self correcting. Willie X
     
  9. Ralph B

    Ralph B Registered User

    Nov 25, 2006
    575
    8
    18
    Napier, New Zealand
    Country Flag:
    I've been successfully setting up Brocot escapements on this basis for years.
    As long as the crutch/arbor screw is not tight, and easily moved, they self adjust as described.
    You wouldn't want to have a tight joint, and then give it a big swing, especially with agate pallets...
    When I instruct customers how to reset the beat, in the unlikely event they need to, I always warn them that they are able to do this on this clock because it has been adjusted to accommodate adjusting in this manner.
    i.e. if a friend asks you about his similar clock, don't try it !
     
  10. daveR

    daveR Registered User
    NAWCC Member

    Sep 10, 2008
    240
    3
    18
    hospital storeman
    melbourne, Australia
    Country Flag:
    Region Flag:
    I would also backup what Willie x has said by addding that a heavy swing on a brocot escapement in the way as is suggested for the 3 train mantle clocks from the 1920s/30s or 40s runs a big risk of breaking the pallets if they are jewelled
    David
     
  11. Ralph B

    Ralph B Registered User

    Nov 25, 2006
    575
    8
    18
    Napier, New Zealand
    Country Flag:
    P.S.
    When I first adjusted one to work in this manner I was amazed at how well it worked.
    With a very loose crutch it went "donk, donk, donk" from side to side and settled down to a virtually perfect beat.
    That was with jewelled pallets as well.
    Not too tight though....
     
  12. daveR

    daveR Registered User
    NAWCC Member

    Sep 10, 2008
    240
    3
    18
    hospital storeman
    melbourne, Australia
    Country Flag:
    Region Flag:
    Though shuddering, I appreciate your experience. I remember though that at one of the classes run by our club, one of our tutors at the time, who doe high level repairs to french clocks mainly, went nuts over someone just carrying a brocot clock around with no damping of the pendulum crutch !!!
     
  13. Ralph B

    Ralph B Registered User

    Nov 25, 2006
    575
    8
    18
    Napier, New Zealand
    Country Flag:
    I'm definitely with your tutor on this.
    If it hadn't been adjusted, and checked, as per my instructions I wouldn't be happy either.
    Pretty much every one of the dozens I've seen over the years were locked up so tight that if I'd pulled the pendulum to one side, and let go, I'd have either snapped off a jewelled pallet, or damaged the scape wheel if it had steel pallets.
    If it's adjusted so the gentlest push moves the pallets, and you carefully check a little swing at a time, you'll be fine.
    I've never had a customer come back to me with either, "this thing broke", or, "I have to keep adjusting it to keep it going".
     
  14. Willie X

    Willie X Registered User

    Feb 9, 2008
    11,294
    507
    113
    Well, it shouldn't be overly tight. It's an adjustment clutch and should be snug enough to hold the beat adjustment once it's manually adjusted.

    If the clutch is loose, it's going to be an ongoing problem, just like it would be on any other clock.

    Willie X
     
  15. Peter Planapo

    Peter Planapo Registered User

    Mar 23, 2019
    71
    2
    8
    Male
    Country Flag:
    I appreciate all the cautionary tales about the fragility of agate/ruby/garnet pallets. I've already made custom-fitted slotted plywood inserts which sit in the base of the clock to hold the pendulum central if I want to carry it. They take 2 minutes to make with a jigsaw. I prefer this to removing the pendulum as I've found that can sometimes cause a rate change next time I set it up.

    And I certainly wouldn't give wild, heavy swings to pendulums to put them in beat. I feel I have to treat them with some respect. I do check the crutch friction, and start with a smaller swing, and if that doesn't do the job, a larger one and so on until it gets there. Added to which on two of mine I can watch the exposed escapement in detail through a loupe during the process, so I do it slowly under control at first before letting it swing free.

    My other two Brocots have internal escapements with steel pallets, so although I can't watch them, there are no jewels to break either, although I am now aware of possible scapewheel damage so I'll be looking out for that. Indeed that might have been responsible for the erratic beat I posted about above (although in my defence, it was like that when I got it).

    I have not seen an internal Brocot with jewelled pallets (do they exist)? If I got hold of one I'd certainly be extra careful.
     
  16. Willie X

    Willie X Registered User

    Feb 9, 2008
    11,294
    507
    113
    #16 Willie X, Jun 14, 2019
    Last edited: Jun 14, 2019
    Peter,
    This subject is totaly overblown. Though delicately made these clocks aren't going to break under their own forces! Ha

    If so, they would have never made it to the present. Most French clocks are carried onto my shop with the pendulum still in place. This is not a good thing but rarely causes any more of a problem than with other clocks.

    You certainly don't need any kind of added structure to hold the pendulum in place. Just take it off and carry it separately ...

    Willie X
     
  17. shimmystep

    shimmystep Registered User

    Mar 5, 2012
    4,077
    70
    48
    Cambridge, UK
    Country Flag:
    Region Flag:
    Given the above, it's prob a bent pivot on escapement arbour
     
  18. Peter Planapo

    Peter Planapo Registered User

    Mar 23, 2019
    71
    2
    8
    Male
    Country Flag:

    Point taken Willie X, and you'd think that nothing short of a hammer could damage some bulletproof clocks.

    But I have found that a clock which I've painstakingly adjusted to a couple of seconds a week may, if I unhook the pendulum and put it back again, which sometimes involves removing the bell too, might be slightly out of regulation after I've put it back, and need regulating again. Why, I'm not sure as I do take reasonable care, although I suspect the Brocot suspension adjusters could have vertical endfloat. One of mine had about 1/2mm, and I shimmed it for zero endfloat whereupon adjustments became more precise and predictable. When I move a small mantel clock, I just hold the pendulum steady but the bigger marble jobs weighing 20-30lbs need two hands, and that's why I made the slotted plates. Unnecessary overkill, quite possibly but certainly harmless, I think..

    In any case the last thing I want is a pendulum banging around loosely in the case. If nothing else, I might damage the Brocot adjuster or the delicate double suspension spring. You might say that would be pretty hard to do, and you might be absolutely right!

    But until I get to a much higher level of experience and expertise (I'll get close to where you are when I'm 100 or so, with luck) I'd rather err on the side of caution, even if jobs take longer as a result; I do this for fun, not money, and everything I do is a learning experience, so time spent isn't really important to me.
     
  19. Peter Planapo

    Peter Planapo Registered User

    Mar 23, 2019
    71
    2
    8
    Male
    Country Flag:
    Yes, it could well be. My other question above was, does it matter? The clock is ticking and striking away within a dozen seconds a day and I haven't even started trying to properly regulate it.

    I've also heard horror stories about these French pivots, that they are hardened and will snap if you so much as look at them cross-eyed. How might I go about straightening a bent pivot, like this one? Intuitively I'd imagine anneal it, true it, burnish it and then harden it again before re-fitting. Is that close or is there a better way? Or are stories of French pivot hardness exaggerated?

    It would be relatively easy to try, since the escapement arbour comes out without splitting the plates.
     
  20. shimmystep

    shimmystep Registered User

    Mar 5, 2012
    4,077
    70
    48
    Cambridge, UK
    Country Flag:
    Region Flag:
    No, they are not exaggerated, though I have straightened many many french pivots without snapping them; the escapement arbour pivots being the main culprit, may well be perhaps due to B) where efforts were previously made by someone else to take it out and replace without splitting the plates, unsuccessfully!:)

    Not to say it can't be done, it can, though there is a chance it won't go well. it really does not take much to bend these upper arbours on French movements.

    I straighten these on a watchmakers lathe, with the pivot in a collet, using a centre at the tail stock as a guide. Very gentle nudging.
     
  21. Willie X

    Willie X Registered User

    Feb 9, 2008
    11,294
    507
    113
    I'm with shim.

    Another point, it's not good to apply extra pressure to keep the plates together while assembeling. So, do what is necessary so the plate will easily drop onto the pillars. This way the plate will drop in place without much pressure being applied to any of the parts.

    WIllie X
     
  22. Peter Planapo

    Peter Planapo Registered User

    Mar 23, 2019
    71
    2
    8
    Male
    Country Flag:
    Thanks for the tips Willie X.

    I think it best to start my plate-splitting and reassembly education with a less delicate and precise English (Smiths, Enfield etc) movement rather than a sophisticated French job.

    I'd guess that trying to lower, parallel, a plate onto a forest of upturned pivots and arbours, without force, gently guiding everything into the right holes simultaneously, is a skill needing a lot of practice and probably patience.
     
  23. Peter Planapo

    Peter Planapo Registered User

    Mar 23, 2019
    71
    2
    8
    Male
    Country Flag:
    That's what I'm wary of for now, never having done it before, so will be practising on less demanding clocks first.
     
  24. Willie X

    Willie X Registered User

    Feb 9, 2008
    11,294
    507
    113
    The pivots will never go in the holes "simuntaniously". Just use a very minimum amount of force when moving the plates and pivots into place.

    Again, make sure the plate fits onto the post easily. You usually have to remove a small burrs here and there (pushed up at the pin holes) and sometimes lightly broach a hole or two (from the inside) to make this happen. Otherwise you may have to use a lot of excess pressure unnecessary.

    Willie X
     
  25. Altashot

    Altashot Registered User

    Oct 12, 2017
    92
    7
    8
    Male
    Country Flag:
    I too have experienced the “self setting” Brocot escapement. The screws were just loose enough to allow it. I then tightened them once it had self adjusted. It worked quite well.

    All the ones I have seen, although possibly only 10 of them, were like that when received.

    I debated whether I should leave them loose or tighten them. I opted to tighten them to lock the adjustment. I don’t like any auto beat features. I then told the clients that the clocks needed to be perfectly levelled. Brocot escapements are possibly the least tolerant. Finicky for sure and not forgiving at all.

    As for your clock Peter, as a hobbyist, doing this for your own pleasure and satisfaction, I’d say if it is running and keeping time... It ain’t broke.

    Enjoy!

    M.
     
  26. Peter Planapo

    Peter Planapo Registered User

    Mar 23, 2019
    71
    2
    8
    Male
    Country Flag:
    I have the very movement to practise on, pic below, a Hermle 5-gong floating balance which came to me like that, plenty of rust. The FB assembly is separate, safe and clean. If I wreck the movement, well it's already a basket case so no loss. If I can get it running, it will be miraculous, but if not I'm sure to have learnt something in the process. I don't have a full set of tools yet, I get them as I need them, but I do have a home-made spring winder which works and a let-down tool. Broaches and so on not yet, I've used sewing machine needles when needed, and I have a lathe though not a watchmaker's thing but a big toolroom version. No collets but a pin chuck that fits into the big chuck, how good the centration is I don't know.

    Thanks M, yes this is all for my own enjoyment, and I have no clients who might come back to bite. So since only I handle my clocks, I'll probably leave the Brocot crutches loose enough for self-setting, which I like..

    Indeed the clock in question with the dodgy beat is in fact keeping very good time, so I'll leave it in peace and direct my energies elsewhere. Of course, that just means that I'll have more questions about some other clock to regale the board with (or even this clock, on a matter of identification), but since you are all such a generous, friendly bunch I'll feel comfortable with that.

    Peter

    20190615_214319.jpg 20190615_214335.jpg 20190615_214419.jpg
     
  27. kinsler33

    kinsler33 Registered User

    Aug 17, 2014
    2,543
    179
    63
    Science teacher, writer
    Lancaster, Ohio, USA
    Country Flag:
    Region Flag:
    Brocot escapements scare me because they're so easy to mess up. I have, however, purchased for more money than I wanted to spend from Timesavers, a book that is quite worth the expense.Escapements Book #3 By Steven Conover

    It's not well organized, being a collection of advice columns from a magazine Mr Conover once issued, but it is down to earth and quite straightforward. I recommend it to anyone who, like me, decided at one point that escapements are trivial. (Spoiler: escapements are not trivial.)

    Not trivial, but not impossible either.

    M Kinsler
     
  28. shimmystep

    shimmystep Registered User

    Mar 5, 2012
    4,077
    70
    48
    Cambridge, UK
    Country Flag:
    Region Flag:
    However, if it is an open Brocot escapement, very different of course, remove the escapement wheel pivot cock and take the wheel out and test for true.
     
  29. Peter Planapo

    Peter Planapo Registered User

    Mar 23, 2019
    71
    2
    8
    Male
    Country Flag:
    Thanks M for the heads-up. I located the book here but it's nearly £50, so I'll keep an eye out for a used copy or maybe try and get my library to find one. I'm sure it would be useful and I'd be happy to have it.

    Meanwhile I have Gazeley's 1956 comprehensive book on escapements as well as Watch and Clock escapements, Keystone 1904 (which is also comprehensive, but rather technical and seemingly written for movement designers).

    I also have the Horological Times Aug/Sept 1987 which has a good Brocot article in two parts by Timothy White.

    Thanks, yes although this particular escapement is internal, and therefore hard to play with, I've done that removal on a superior external-escapement Marti, even attempting to adjust the separation of the pallet jewels (they had been mucked about with clumsily with a screwdriver, or a chisel). I approached the job with trepidation, but with guidance from the books it wasn't so hard. I'm sure I didn't do a great job but it wasn't running when I got it and now it runs quite sweetly so it couldn't be all bad. I look forward to more Brocots but they seem to be a bit pricey unless I can pick them up on the cheap from house clearance dealers.
     
  30. manuelf

    manuelf Registered User

    Jun 21, 2015
    16
    0
    1
    Country Flag:
    #30 manuelf, Aug 18, 2019
    Last edited by a moderator: Aug 20, 2019
    Hello colleagues, according to the graphics it seems that the teeth of the exhaust wheel are eccentric and sometimes it receives in the center of the palette and in others below the center. regards
     
  31. manuelf

    manuelf Registered User

    Jun 21, 2015
    16
    0
    1
    Country Flag:
    #31 manuelf, Aug 18, 2019
    Last edited by a moderator: Aug 20, 2019
    There are some Asian watches where the milestone is automatically regulated. They are resting exhaust, the anchor body enters its axis with sliding adjustment and a U-shaped spring rubs the shaft groove.
     

Share This Page