Sessions verge arbor disaster

Discussion in 'Clock Repair' started by THTanner, Dec 6, 2018.

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  1. THTanner

    THTanner Registered User
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    Before I started on this troublesome Sessions mantle clock I read through multiple postings on the board about Sessions pallets, strips, entrance and exit drops, etc. Clearly these pose some interesting issues.

    The clock had not been serviced for 20+ years and had a lot of other issues, but had been running fairly well according to the owners. I had been to their house to repair a pendulum on their GF clock when I saw the old Sessions and asked if it needed service.

    On the bench in the shop I noticed that the dog bone pivot posts for the verge held the arbor at an angle relative to the plates instead of being perpendicular. There was almost no end shake and it didn't move smoothly, but it would actually run for several hours before stopping. I adjusted the dog bone on one side to get everything lined up, the pendulum amplitude increased a bit, and the clock ran great on the test stand for two days keeping great time.

    It was difficult to see when assembled, but when I took it apart for service I found the arbor had a curious bend in it of several degrees. I guess the last service person offset the bend by setting the pivot posts at a bit of an angle? The pivot holes had enlarged enough to allow it to keep running - or perhaps had been broached out at an accommodating angle?

    Anyway - annealed and straightened - bushed and polished -and running great.

    IMG_3093.JPG
     
  2. R. Croswell

    R. Croswell Registered User

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    I was reading with anticipation of a great disaster story, just all in a day's work. Glad you got it straightened out.

    Several decades ago I did have a Sessions verge disaster, or at least it seemed to me to be so at the time. I decided that the pallet spacing needed to be changed (probably a mistake) and I didn't know the darn thing was hardened! Well I ended up with most of the verge in one hand and the pallet from one end in the other. So now what. Well I just "glued" it back together with something similar to JB-Weld. That was maybe 40 years ago and it still runs fine. I got a replacement verge but never got around to installing it, and now I'm not sure where it is and probably won't change it anyway. So maybe that wasn;t a disaster either!

    RC
     
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  3. THTanner

    THTanner Registered User
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    Under what conditions and for what reason would someone bend the arbor like that - and leave it bent? Before straightening it I worked it between the plates several times trying to see if there was a good reason to do that, but never did see anything that would make for a good excuse.
     
  4. Willie X

    Willie X Registered User

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    The movement could have been dropped, or someone prying around with a big screwdriver (with the movement still in the case) is not uncommon. I can't think of any logical reason someone would bend an arbor that was fully adjustable. The phrase "you can't fix stupid" comes to mind. :) Willie X
     
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  5. R. Croswell

    R. Croswell Registered User

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    I agree but have seen the same thing.

    RC
     
  6. David S

    David S Registered User
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    Let's not go too far blaming some heavy handed repair person.

    Last fall I was asked to service a Sessions Adams eight day half hour cathedral gong turn back. And the verge arbor was indeed bent such that the pivots weren't on the same axis. It appeared bent in two planes. See pics below.
    anchor arbor bent 1.jpg anchor arbor bent.jpg

    It is also evident here in the straightening jig.
    anchor arbor straightening fixture.jpg
    The arbour was soft enough to be able to be straightened without heat or annealing.

    David
     
  7. Willie X

    Willie X Registered User

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    I would say that Session clocks seem to get more abuse than any other brand. The cases and movements are often in pretty rough shape. Willie X
     
  8. THTanner

    THTanner Registered User
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    Interesting that this is not so uncommon. First time I have seen it, or seen reference to it, but I have not done a lot of Sessions clocks.

    I doubt this was bent by a screw driver. The arbor was not at all soft when I first tested it to straighten it with flat blade pliers and the other end in a small vice. It would not bend back at all. After annealing it was the usual softness and bent back with minimal effort. Just another curious lesson for a rookie.
     
  9. David S

    David S Registered User
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    Agreed, I don't think it was pried on by a screwdriver in situ or it would have bent the pivots first. Also I didn't think the arbor would be that hard since it was rather aggressively swagged to secure the verge. Unless they hardened the entire assembly afterwards.

    I think this is a manufacturing issue.

    David
     
  10. Willie X

    Willie X Registered User

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    Never underestimate what can be done with a "big screwdriver" ... especially when it's being wielded by a determined allsimers patient. Lots of my customers have Parkinson and/or Allsimers in various stages, a tough place to be. I think it's worse for the family than the person with the condition. Willie X
     
  11. THTanner

    THTanner Registered User
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    ==================================
    I think this is a manufacturing issue.
    David

    ==================================

    So perhaps a swagging error that bent the arbor and it has always been that way? That would make some sense for why the owner said it ran fine for more than 30 years - compensated for, I guess, by misaligning the pivot posts.

    "Unless they hardened the entire assembly afterwards." - - Pictures don't show good color, but the arbor was a bit blue - not as dark as the verge - but bluer than many I have seen - so perhaps it had been hardened a bit at some point. The pallet faces were in surprisingly good shape for not having been serviced in a long time.

    I think I will keep the clock for a couple weeks longer than usual to make sure. So far two days of running fine.
     
  12. Keith Conklin

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    So now what. Well I just "glued" it back together with something similar to JB-Weld. That was maybe 40 years ago and it still runs fine. I got a replacement verge but never got around to installing it, and now I'm not sure where it is and probably won't change it anyway. So maybe that wasn;t a disaster either!

    RC[/QUOTE]

    This is kind of what I was goofing on in another post. I have some dubious repairs I have performed on my personal clocks and they work fine.
    What worries me is when I die and my kids sell off my collection, I'm lying in my grave and someone on this forum acquires the clock, lambastes the repair and its dog pile on the dead guys clock repair.
    Sheesh! what a way to go!! I cant stop chuckling about this.
     
  13. THTanner

    THTanner Registered User
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    I think David S probably nailed it as a factory feature. The bend would appear to be from the swagging pressure and they let it go out bent from the beginning. There are no marks on the arbor to suggest any effort bending it that way otherwise.

    So on my grave stone I am going to ask that it says - - "The Factory Did It" -
     
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  14. R. Croswell

    R. Croswell Registered User

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    Not only a manufacturing issue but also an inspection and quality control matter as well. Better buy that headstone now and have it say what you want and let the kids add the date later.

    RC
     
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  15. THTanner

    THTanner Registered User
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    Not to beat a dead horse, but I have been puzzling about this situation for a couple of days. I don't think this was a "factory error".

    This clock has been in this family for 30+ years and supposedly running pretty well for the last 10 or so. Yet these pallets showed almost no wear. I barely had to do a finish polish on them. I think what happened was that someone heated the arbor, bent it to open the swagging, removed the verge strip, put in a new one, bent it back to secure it and had to bend it past parallel to get it tight, then hardened it. When I straightened the arbor i had to give it a few knocks with a punch and hammer to get the verge tight again. The arbor and crutch, and the condition of the pivots seem to indicate that the verge strip is a lot newer than the rest.

    Anyway - a good lesson and something I will check more carefully from now on.
     
  16. R. Croswell

    R. Croswell Registered User

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    It may remain a mystery, but I would suggest that the bent arbor probably happened when the pallet strip was staked in place, either at the factor and gone unnoticed, or perhaps later by someone restaking to tighten a loose pallet strip. If the pallets show no wear perhaps they had been reground at some point.

    RC
     
  17. Bruce Alexander

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    Wouldn't the pallet/verge depth be set by an assembler at the factory via adjustment to
    ?

    I really don't know the details of how these movements were assembled and adjusted in the factory. I imagine that most of it was automated somehow. I can't see a line of workers cobbling movements together wheel by wheel the way we do, but I think it unlikely that such an important, defective part would have: (1) gone undetected until assembly, and ( 2) have a final assembler/adjuster alter the plate to accommodate it. No doubt stranger things have happened and if the clock still functioned within acceptable limits at testing, it would probably have left the factory. I'm not saying it couldn't have come out of the factory that way, I'm saying that I think it more likely to be an "acquired" state. In any case, nice job THT, and great catch David S. You have the eye of a Machinist.

    Ready 2 Assemble.JPG
     
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  18. David S

    David S Registered User
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    #18 David S, Dec 8, 2018
    Last edited: Dec 8, 2018
    :) Actually Bruce, I have the eye of a Quality Manager. For the last 35 years of my career I was involved in designing and manufacturing consumer products. In the early 90's I was transferred from the design department to head up the quality group. At first I thought I had drawn the short stick, but it turned out to be a great opportunity.
    So when I see clock movements and all their parts I am always curious as to how they were made in high volumes. For this verge assembly in question, I try to picture how the verge would be swagged to the arbour. Probable loaded into a fixture to locate the components and then some sort of manual or powered arbor type press to do the swagging, limited by some sort of stop. And then I picture that at some point due to a defect in the arbour like an inclusion or something, the swagged piece actually breaks off. The operator may notice that the verge is loose and set it aside, but may not notice right away that the little piece has fallen into the fixture and now the arbour doesn't sit straight, but not overly noticeable. Now the assembly will be bent.

    At our company, manufacturing takt times could be say 15 seconds. Operator loads the components, presses the buttons removes the assembly and repeat. Four a minute, 240 an hour. It is very easy to generate a significant number defective parts, before they ultimately get noticed. And then once something is found to be wrong, go back and find all the defective ones can be a challenge.

    However as you note, I would love to know more about manufacturing assembly processes in the 1800's and early 1900's.

    David
     
  19. Bruce Alexander

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    I can see that happening David. Everything I've been reading lately about machining seems to stress that parts, fittings, tool holders, etc are absolutely clean before any work is done to the material or part. That still wouldn't explain how the plates were modified in a timely fashion to make the defective verges work. I imagine that the poor souls whose job was to fit and adjust the verges to the proper depth (if that was the case) would have been more than a little upset. We're not exactly talking "Santa's Elves" here. :chuckling: Let me put it this way, if I were under a lot of pressure to crank out X number of adjusted movements to be tested and someone up the line from me was making it impossible for me to keep up, I'd be a little vocal about it. On the other hand, if I were worried about losing my job in a non-unionized shop, I might just inform my boss, get it done as best I could and stop by the local bar on my way home.
     
  20. Willie X

    Willie X Registered User

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    It was get er done and good enough is good enough. There were always the necessary foremen here and there to make sure the product at the end of the line/s had the expected level of quality.
    Willie X
     
  21. THTanner

    THTanner Registered User
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    My first job out of college was quality control tech at a Canon shop in So Cal making a variety of products like cameras and printers. Each machine had a QC manual and sign in sheet where we would work the floor in patterns, "randomly" taking a part off the machine, make an entry, then take it to the lab, measure it and enter the data into a log. At the end of the day the log entries were analyzed for deviations and if the machine was outside the QC specs we shut it down from production and notified the machine techs to retool. This was in the 70s. I have seen some systems today where artificial intelligence controlled lasers check each part as it comes off the machine. So now I guess the QC people check the laser checkers.
     
  22. Bruce Alexander

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    Okay, but these movements are pretty old, well used machines. They've been around the shop at least a few of times so I doubt very many of them are in newly manufactured condition/settings. Assume they're a Century old, have been idle half that time, and have a BPH of 8,000. According to my little calculator their verges would have sustained a little over 3.5 Billion beats. Modify my assumptions however you like, that's still going to be a lot of cycles.
     
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  23. THTanner

    THTanner Registered User
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    I don't know what a "proper" amplitude is for these, but it is now keeping great time with a side to side amplitude of 1 1/4 inches.
     
  24. Bruce Alexander

    Bruce Alexander Registered User
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    That sounds pretty healthy to me THT. Is that center-line or does it include the bob?
    Getting an escapement healthy again always gives me a real sense of accomplishment but I'm more novice than pro and easily amused, so there is that...:chuckling:
    Enjoy your precision handy work! :thumb:
     
  25. Willie X

    Willie X Registered User

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    That sounds good. You should see that overswing now, especially on a fresh wind. Willie X
     
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  26. THTanner

    THTanner Registered User
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    That is total distance the center line travels - which is double the swing when it came in. Moving those dog bone pivot posts certainly is a delicate operation.
     
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