Do solid plates really make a difference besides aesthetics?

Discussion in 'General Clock Discussions' started by Isaac, Feb 13, 2018.

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  1. Isaac

    Isaac Registered User

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    Just wondering your thoughts on this. Besides high precision clocks that are designed to keep accurate time in a variety of conditions, do solid plates really make that much of a difference in the integrity of a clock movement?

    Take for instance an earlier Seth Thomas Sonora with cut out plates - both movements did not have solid rear plates until later on. I presume that this was more for show, because the front plates of both movements were still cut out. Solid plates especially look nice when they're lacquered and shiny, but besides looking more expensive I don't see any other benefits.

    What is your experience/thoughts on this?
     
  2. leeinv66

    leeinv66 Moderator
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    There is no flex when you have solid plates. The same cannot be said for cut or punched plates.
     
  3. Isaac

    Isaac Registered User

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    Is there enough flex for it to be noticeable in a movement's operation?
     
  4. leeinv66

    leeinv66 Moderator
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    Yes, especially in spring driven clocks. I have had some that will not run unless all four corners of the front plate where securely screwed down.
     
  5. Willie X

    Willie X Registered User

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    I don't think it would make much difference, unless the plates were very thin. Many high stress parts in aircraft, aerospace, and race cars are 'Swiss Cheesed' severly. On lumber or plywood beams. I think the national code on holes is: the hole can be up to 1/3 the width of the beam and no more than 1/4 the width of the beam from the edge.

    On the 'racking' forces mentioned in the last post, plate thickness and the stiffness of the mount would probably play the biggest role.

    Willie X
     
  6. Bruce Alexander

    Bruce Alexander Registered User
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    They not only "look more expensive", they are more expensive. I agree with Peter, a solid plate will resist flexing under spring load better. A cut out design will retain most of the rigidity, but some is lost. Also, Seth Thomas tweaked their designs. Their Number 89 8-day Time and Strike was a workhorse for used in many of their clocks, including their Sonora line. The mechanism was made in many versions. Their 89 AD had a solid rear plate. It's a nice improvement in many ways but one I've noted is that the T-4 Gear often showed accelerated plate wear. There wasn't a lot of "extra" brass around the pivots for this Gear Assembly in the cut out plate design. Although it wasn't really necessary, it is not uncommon to see that someone has placed Rathbun type "repairs" to this area of the plate.

    The 89's and the Sonora 100's series of movements are concealed. There is no good reason to spend (and charge more) to make a clock's movement look more expensive when the owner will very seldom look at it. That's especially true in a very competitive market place.
     
  7. novicetimekeeper

    novicetimekeeper Registered User

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    some 18th century longcase makers, particularly provincial ones, would use cutouts in the plates to save the brass which was incredibly expensive. Makers in Northern England also had cutouts behind the chapter ring.

    We call them cutouts but they were there in the original casting not removed later.

    It didn't catch on, despite the high cost of brass, in fact they weren't even a feature of 20th century British clocks.

    The only exceptions were the skeletonised clocks that became popular in the 19th century.

    Probably part of why the British clock industry failed to compete.
     
  8. leeinv66

    leeinv66 Moderator
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    The scale of the American mass production of clocks kill the British clock industry. And that system was all about making movements as cheap as possible. Hence they designed plates that used the minimum amount of brass. I would argue the quest for cheapness was at the expense of functionality towards the end of that era.

    While it is true race cars, aircraft and aerospace vehicles are 'Swiss Cheesed', there is a trade off in play in those applications. They use less material because they manufacture from or modify with lighter and stronger materials. They do not just drill holes in mild steel or stock aluminum and hope it will carry the load. Which is effectively what they did when they mass produced the brass plates under discussion. They just removed material.

    I agree the "racking' forces I mentioned would be cured with thicker plates. It would also be cured if you used full plates of the same thickness as the originals. However, both these cures require the use of more brass and that is counter to the aims of mass production.
     
  9. jmclaugh

    jmclaugh Registered User

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    I think the only UK clock company which almost exclusively didn't use solid plates was The British United Clock Company, much of the production methods and movement designs were based on Ansonia but alas that didn't stop the business failing. Most of the others did however adopt mass production methods to compete with cheaper foreign producers.
     
  10. Isaac

    Isaac Registered User

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    I do agree with your logic, but wouldn't the benefits of having solid plates be undermined by having cut out plates on the front of the movement?
     
  11. Bruce Alexander

    Bruce Alexander Registered User
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    #11 Bruce Alexander, Feb 14, 2018
    Last edited: Feb 14, 2018
    Yes, I think that you're right. In reference to the Seth Thomas 89 A-D, since both plates are securely fastened at five points when assembled, the solid plate would impart more resistance to flexing (or racking) than the movement had previously but not as much as it would have if both plates were solid. That's assuming that the plate thickness remained unchanged, which I believe that it did. The decision was probably a cost saving measure. Resistance to racking may have only been one of several reasons for the modification in design. I don't know,
     

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