Understanding Seth Thomas 89 Movement Variations

Discussion in 'Clock Repair' started by Dave T, Oct 12, 2019.

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  1. Dave T

    Dave T Registered User
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    #1 Dave T, Oct 12, 2019
    Last edited: Oct 12, 2019
    I just recently cleaned and serviced a 89 C and was very well pleased with how it runs and the amplitude of the pendulum. Indicating to me that it is a strong and healthy movement.

    So, I have an old ST with an 89 AD movement, that has never been very reliable. I tore it down and serviced it too. It does have a little more play in the bushings and could use about 3 new ones. But, I assembled the time side (which has always been the problem - strike side works great). And the train runs free with no spring. So, I put the spring in, wound it up and it still doesn't have much amplitude, and not near as much as the C movement (above).

    So, here's one question and would appreciate any input from others who might help me analyze this.
    What's the difference between the two movements, and how do you interpret the ST descriptions.

    Seth Thomas 89 comparison A to C.jpg
     
  2. bruce linde

    bruce linde Technical Admin
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    a tired mainspring? Escapement? Mostly sounds like a tired mainspring… Why don’t you swap out the wheels and see what happens?
     
  3. Willie X

    Willie X Registered User

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    They are all basicly the same. There are many variations though within the group.

    A slight pendulum swing on an 89 is usually caused by wear in the upper pivot holes with the associated rough pivots. If the train is in good condition look for a badly worn escapement. The pallet tips will wear to a point where there is no clear delineation between the dead faces of the pallets and the impulse face. This alone can make for an unhappy pendulum swing.

    I am working on a S-T 89 now. It has severe wear in the upper train but a good escapement. It's doing a solid 1 1/4" on the pendulum swing.

    WIllie X
     
  4. R. Croswell

    R. Croswell Registered User

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    ST made quite a few variations of the No. 89 - some had solid back plates, some cut out, some had a passing bell on half-hour, there were some quarter strikers, I believe thee was even a bim-bam striker, plus a couple models that were paired with a separate Sonora chime unit. I wish someone would produce a table listing all the variations. That said, I agree with Willie, the difference in performance between the No. 89-C and 89-AD is more likely some issues with the 89-AD than any design differences. The adjustment of that strip deadbeat escapement, and pivot/pivot hole wear being probable causes assuming that everything has been cleaned (taken apart and disassembled) and oiled.

    RC
     
  5. Dave T

    Dave T Registered User
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    Appreciate the inputs.
    Think I can eliminate the springs. I cleaned and oiled all four of them in both clocks, and can't tell any difference in any of them.

    The first 89 has at least 1 1/2" swing and has a healthy beat.

    The second one is about 1/2" swing and sounds anemic.
    The escapement looks good on it, (to me). I do think the pivots on the verge could use a polish, but didn't think it would have much bearing?? Would it?

    At this point all I know to do is replace some bushings and polish pivots.
     
  6. Dave T

    Dave T Registered User
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    You and I posting at the same time. I do have the Seth T variations complete list. I'll post it here.
    Can you elaborate on the adjustments of the strip deadbeat for me. I was studying that, and it appears that the pivots are stationary. There is hardly any lock.
    Seth Thomas 89 movements.jpg
     
  7. Dave T

    Dave T Registered User
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    Pretty good video of deadbeat here.
     
  8. Uhralt

    Uhralt Registered User
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    Can you post a picture of your escapement? There should be a way to adjust the verge for more lock. If the teeth fall on the impulse face, that would rob a lot of power.

    Uhralt
     
  9. Willie X

    Willie X Registered User

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    Look up 'adjisting dead beat escapement'.

    Basicly, every e-wheel tooth must always fall onto a 'dead' pallet face, then the pallet moves about 1/2 mm across the dead face and crosses a sharp transition ledge onto the 'impulse' face. Here the tooth slips quickly across the impulse face before sliding off the tip. Then the exact same process repeats on the opposite pallet.

    WIllie X
     
  10. Dave T

    Dave T Registered User
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    Willie/Uhralt,
    I've made a video and still trying to get it posted here.

    But I think I see the pallet landing on the impulse surface as you and others have suggested. So if that's true, how do physically adjust it?
     
  11. Willie X

    Willie X Registered User

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    #11 Willie X, Oct 12, 2019
    Last edited: Oct 12, 2019
    First, take the pallet assembly out and inspect it for wear. No need to waist your time adjusting the pallets if they are in a worn down condition.

    There are two little brass dogbone shaped arms riveted inside the plates. The arms can be carefully moved up or down to adjust the pallet's height. The pallet arbor should remain close to level after adjusting.

    WIllie X
     
  12. bruce linde

    bruce linde Technical Admin
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    upload the video to youtube and then copy and paste the youtube url into a post here....
     
  13. Dave T

    Dave T Registered User
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    Bruce, I normally do that via Youtube, but the video for some reason (in mp4 format) is not usable.??
    Possibly codec error? Beyond me.

    All I'm trying to do is adjust my escapement. I do think the verge is adjustable, but it's riveted on both sides of the frame and real tight. Evidently I managed to move it some, as the clock quit running altogether. So I moved it back and it's where I started.

    This isn't at all like any adjustable verge I ever worked with. I don't know how to adjust it, and not sure that's what is needed.
     
  14. Tom Kloss

    Tom Kloss Registered User
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    Hi

    Tran's Seth Thomas book list 14 variations of the 89 movement.

    Tom
     
  15. Dave T

    Dave T Registered User
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    Just saw this Willie, Thanks!!!! I thought that's what I needed to do. Now you've confirmed that for me.
    So at least, I know I'm not headed down the wrong trail. I'll take it out, and take some pictures for you all. I did adjust it evidently in the movement, as the clock stopped running! So I moved it back and it's where I started.

    I'll keep you posted.

    Dave
     
  16. bruce linde

    bruce linde Technical Admin
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    worked for me... probably a network or browser-needs-be-restarted thing...

     
  17. Dave T

    Dave T Registered User
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    Amazing, not sure how you got that. I kept getting errors and unable to play it. Sorry the video isn't very clear. But I still think I need more lock. Now that Willie explained I'm on the right trail, how do you move those dogleg adjustments? They are tight!
     
  18. Uhralt

    Uhralt Registered User
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    The lower pallet is hard to see in the video but the upper pallet clearly needs to be moved closer to the escape wheel. The teeth are landing on the impulse face. These dog bones are sometimes hard to move or move abruptly too much when using pliers to move them. I have made a tool with a slot in brass pipe and a cross bar to turn the rod. The slot is such that the dog bone fits in. I use it to move the dog bones by turning the tool with the cross bar. You can also use a flat stake and a small brass hammer to move the dog bones cautiously towards the wheel. Just a little at a time, testing in between.

    Uhralt
     
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  19. Bruce Alexander

    Bruce Alexander Registered User
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    Dave,
    In the past I've found it all too easy to move one of the verge pivot holes more than the other one. If that happens, even a little, you can get binding. Assuming that your verge surfaces aren't worn, when you make your small incremental depth adjustments on both plates, make sure you still have end-shake.
    Good luck with it.
    Bruce
     
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  20. Dave T

    Dave T Registered User
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    Good to know Bruce, I think so far I've been able to move only one side. It has made a very slight difference in amplitude, but I'm not there yet.
     
  21. Dave T

    Dave T Registered User
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    Trying to picture what this tool looks like and how to make one. I think If I could control the movement and then watch the changes it would be much easier to get maximum amplitude. Right now it's (hit and miss).
     
  22. Uhralt

    Uhralt Registered User
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    Her are
    Here are two pictures. One shows the tool in total and the other the slot where the dog bone needs to fit in. I made this (in a hurry) to set the depth of verges that are outside the plates. I could have made it better with straight edges rather than the half round of the cut out, but it works well. For your dog bones, because they are inside the plates, you need to have cut outs on both sides of the pipe and probably need to use a pipe or rod with a smaller diameter. But I think you'll get the principle.

    Uhralt
    tools1.JPG tool2.JPG
     
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  23. Dave T

    Dave T Registered User
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    Thank you! That's what I somewhat had envisioned. I'll see if I can make something.
     
  24. R. Croswell

    R. Croswell Registered User

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    Dave, others have covered this pretty well except perhaps one small but important point. When setting the "lock" it is not a case of more is better. No power is transferred while the escape wheel tooth is on the locking face. All that's required is a good positive lock on the dead face just a little past the impulse/dead face transition line. Excessive lock is counter productive. Don't confuse "lock" with "over swing". (See the video in post #7), lock is the point where the tooth touches down on the dead face. Over swing is the distance the tooth continues to travel after it makes contact. If the clock is healthy it will have significant over swing as seen in that video. The duration of the impulse is fixed by the physical size of the impulse face and is not affected by the amount of lock so long as the lock is on the dead face.

    RC
     
  25. Willie X

    Willie X Registered User

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    #25 Willie X, Oct 14, 2019
    Last edited: Oct 14, 2019
    On this clock it's difficult to actually see the pallet contact points but it's easy to check the adjustment by simply watching the movement of the e-wheel (using good magnification). When the crutch is slowly moved by hand, the
    e-wheel should stop 'dead' (no recoil) after the tick. When the crutch is slowly moved back toward center, just a small amount, you should see the impulse kick in with a quick foward movement of the e-wheel followed by the next tick and another 'dead' stop with no recoil, etc. etc. etc.

    For practice you can watch the second hand on any modern GF clock. The e-wheel motion, on a deadbeat escapement, is always a simple start - stop with never ever any backwards motion.

    WIllie X
     
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  26. Dave T

    Dave T Registered User
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    I have considered the overswing, but guess I was getting confused in trying to get this movement to perform the same as the other 89 I just finished.
    This movement has more bushing wear than the other. And there are no doubt other differences between the two, that makes one 'healthier' than the other.

    I do have good positive lock on the dead face and more swing than when I started. In video #7 - that video was before I adjusted the pallets. It had very little swing and I think the pallets were landing on the impulse face.

    Now that I've adjusted it, it has about 1 1/4 - 1/2 swing and is locking on the dead face. Sounds like I may have it as good as it will get without rebushing, new springs, etc. Think I'll leave well enough alone!

    Adjusting pallets on this movement was new territory for me. All the others (that I've ever worked on) have screws that you can loosen to move the anchor. Which is a whole lot easier task. Guess I just needed to get through the learning curve.

    Thanks!
     
  27. Dave T

    Dave T Registered User
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    Well, now it's time to move over to the strike train. As best as I can remember it was striking okay before I tore it down. Now, it stalls occasionally during the cycle.
    I haven't been able to identify any particular reason. But I do see the governor slowing down also during the cycle. And then, occasionally it stops altogether during the cycle.

    Not sure how to go about resolving this one. Except to tear it down again and closely look at the meshing of each pair of gears one by one. And/or to replace bushings.

    Need some suggestions on how to approach it. Hate to tear it down again as these are difficult to re-assemble with the full front plate!
     
  28. shutterbug

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    Yes, something is robbing power. The only other possibility is that there's not enough power being supplied. But be careful there.
     
  29. Willie X

    Willie X Registered User

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    "Tearing it down" should not happen until AFTER the 'aha there's my problem' moment ...

    WIllie X
     
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  30. Dave T

    Dave T Registered User
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    Yes I do like that idea, but so far I haven't had that "aha". o_O
     
  31. Willie X

    Willie X Registered User

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    Just keep studying it. It's time well spent. :) Willie X
     
  32. Dave T

    Dave T Registered User
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    Well, I've spent three days studying it, and still haven't had that 'aha' moment.
    A couple of things I have considered. The train is a little noisy when it runs through the cycle. But, I've seen a lot of clocks that are.
    The other thing I've considered is that the hour tube is a little loose in the frame. If I move the hands I can see the play in it. Considering bushing the front side of the hour tube?? Any thoughts on that?

    Also, when the time strikes the hammer bounces.

    So, I've got it torn down again!!! I'm going to replace 4 bushings in the time side on the 3rd and 4th wheels. Still not completely satisfied with it. Seems as though it has to be exactly in beat to continue running without stopping.

    Look at all the pivots closely and polish, re-assemble and see what happens.
     
  33. R. Croswell

    R. Croswell Registered User

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    I guess I missed something, I thought you had the time side working OK with 1 1/2" swing which isn't bad for a short pendulum strip deadbeat. I thought the current problem was that the strike train stalls during the cycle.

    As for the hour pipe and lost motion in the hands, this type of clock where the center arbor is not part of the power train will always have a little backlash in the gears. If it didn't it would have excessive friction and stop. As for the hour pipe wobbling or being loose in the hole in the front plate, that's mostly just an annoyance. Very little power is used to move the hour hand and this is not usually a problem with the running of the clock. You can bush the large hole in the front plate and the inside of the base of the hour pipe if it really bothers you but I think most people just live with it.

    Bushing the 3rd and 4th time train arbor pivot holes may improve the performance of the time train if these holes are worn but are not likely to solve the strike train issue.

    If I understand correctly, the strike sequence begins but the wheels turn sluggishly and sometimes it stalls out. Is that correct? The strike train failing to start is an entirely different problem.

    Before tearing it down, let down both main springs into clamps or wire binding, release the clock springs, make sure you can jiggle the main wheels back and forth with absolutely no power from the spring. Place the movement on its back. use a probe to "lift" each wheel up to the front plate and release it. It must drop back down quickly on its own. Now place the movement face down and do the same thing. We are looking for a tight pivot and the most probable cause being a pivot that got bent during assembly, or a bushing that was installed crooked or broached at an angle that seemed OK alone but not being perpendicular to the plate (parallel to the pivot) now causes it to bind. Sounds like a power problem, I doubt that it is a spring issue unless someone installed the wrong spring.

    RC
     
  34. Dave T

    Dave T Registered User
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    Great info here RC. Thanks so much! A lot to digest, but believe me I will study this. I've inserted some answers above. (underlined and Italics) Unfortunately, I've already got it torn down again.
     

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