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GWR 813 Failure

Discussion in 'Steam Traction' started by nick813, Apr 26, 2022.

  1. 30854

    30854 Resident of Nat Pres

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    Please tell me you didn't used to work at Three Mile Island! :)
     
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  2. Steve

    Steve Resident of Nat Pres Friend

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    I think most places would do similar, having risk assessed the situation. It is just the railways that don't like to do such repairs. I've had a lifetime of doing similar, generally falling into two types; those intended to keep things going until a more permanent repair can be carried out and those where the repair is considered to be the equal of or better than the original and can remain in place.
     
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  3. RLinkinS

    RLinkinS Member

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    No, somewhere much closer than that. There is much to learn from Meccano but you need to use certified materials.

    Sent from my SM-A105FN using Tapatalk
     
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  4. brennan

    brennan New Member

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    Nobody has yet suggested metal stitching. In the marine industry I have seen some quite spectacular disasters put back together using this process and these were all approved by the classification society.
     
  5. D1039

    D1039 Part of the furniture

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    See post 35
     
  6. brennan

    brennan New Member

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    Herewith post 35 - "For what it's worth, I've commissioned a few 3D scans, mostly for fabrications where we need the as-welded form. I've never put out a single casting for manufacture.

    The process of scanning and interpreting is increasingly routine; the main trick is in getting a 'watertight' surface that the software can actually recognise as a closed solid. Even then, relatively run of the mill CAD software has got quite good at stitching up surfaces containing gaps where the part was sitting on a support.

    Taking the example of scanning an existing part as a pattern, once you've got that watertight solid, things like scaling up for a shrinkage allowance and adding a machining allowance on the appropriate surfaces are basically trivial with current software.

    Given that 813 had a casting already, it seems to me that in the interests of authenticity, if it's cost (and performance) competitive to produce a new casting, that is more desirable than to replace with a fabrication. Using a stronger steel (or maybe SG iron) casting in place of the original grey iron seems like an acceptable allowance for the original having broken. No, you probably wouldn't do it that way in modern industry, but there's not much modern about 813 either."


    What has the foregoing got to do with metal stitching? I'm suggesting this process ; https://en.wikipedia.org/wiki/Metal_stitching.
     
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  7. Steve

    Steve Resident of Nat Pres Friend

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    I'm not too sure that metal stitching would be a viable solution on its own due to the position of the break and the forces involved. It could be used as a part of a belt and braces repair, though.
     
  8. Jimc

    Jimc Part of the furniture

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    @nick813 . I expect you are aware but in case not the latest NRM Swindon drawings catalogue lists a good number of drawings for PTR locomotives including several relating to "Trailing Spring Gear Engines 22-27 Port Talbot Railway".

    Jim C
     
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