Dating Clues for Optimus No.45 and 48 stoves.

Discussion in 'Optimus No:45' started by kerophile, Sep 14, 2014.

  1. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    It is difficult to date Optimus stoves, as unlike Primus, the manufacturer did not date-code their stoves. However, by studying the dated Catalogues and Brochures contained within the CCS Reference Section, it is possible to follow small design changes which occurred during the production period of stoves.

    I have been looking at the positioning of the air-release valve on Optimus No45/48 stoves, as an aid to dating particular examples, and here are some observations I have made:

    1410701271-St.370.-Op.45-Sept-14-1.jpg

    With stoves things are never simple. Over its lifetime the air-release screw on the Optimus 45 would seem to have moved around a bit!

    1. From the top of the tank, in the 1920 and 1929 catalogues.

    2. To the top of the fuel filler cap in the 1932, 1933, and 1939 catalogues.

    3. To the side of the filler upstand in the 1957/8 catalogue.

    4. To the top of the fuel filler cap in the 1959 catalogue.

    5. Finally, back to the side of the filler upstand in the 1972, 1975, 1984, 1985 and 1989/90 catalogues and brochures".

    I would welcome any comments or observations on the above, and will update the list, as and when additional dating information becomes available.
    Best Regards,
    Kerophile.
     
    Last edited by a moderator: Jun 26, 2015
  2. Doc Mark

    Doc Mark Subscriber

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    HI, George,

    Very nice job of laying out that interesting information for us. From what I've seen, and can remember, I think you're pretty much on the mark, here, and thank you for laying it out in a clear and concise manner. Well done! Take care, and God Bless!

    Every Good Wish,
    Mark
     
  3. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi, The type of "pip" used in the Non-return valve of the stove provides another possible clue to its age:

    I believe that the one-piece moulded pip came into use with the Swedish Manufacturers around 1960. Here is my Optimus evidence:

    Optimus was still using "cork holder" #267 and "cork packing" #268 for their NRV in 1957/8 according to their catalogue.

    In their 1972 catalogue this assembly has been replaced with a one-piece "rubber cone" #263

    This rubber cone part is also shown in a 1970s brochure for Op.96/96L stoves, but the Optimus spares numbering system has now changed and the part number is #2252.

    If your stove is fitted with a one-piece rubber "pip" or cone it was likely manufactured after the early 1960s.
    Best Regards,
    Kerophile.
     
  4. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    In 1957/58 Optimus proudly launched a new feature on their Optimus 45 and 48 stoves; a "sunken" filler screw.

    https://classiccampstoves.com/threads/9292

    The spigot was mounted in a depression in the top of the tank, ensuring that the tank could not be over-filled and thus maintained the required air-space above the fuel.

    Primus had used this feature since the early 1920s, but it was likely protected by patent over the intervening years.

    If your Optimus 45 or 48 stove has a "sunken" filler, it must have been manufactured after 1957/8.

    Best Regards,
    Kerophile.
     
    Last edited by a moderator: Jul 1, 2015
  5. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Brian Miller proposes dates for marking changes on burners here:


    “Non- Op.111 roarer burners made between 1962 and 1969 were marked Optimus Primus. Roarer burners made between 1969 and 1976 were marked Made in Sweden because Optimus then were making Optimus, Primus and Svea stoves so the burners could be used on any make without it being obvious that the same maker was making three brands.

    Silent outer caps were marked Optimus Primus between 1962 and 1969. Between 1969 and 1976 the silent outer cap marking changed but I am not certain whether it was changed to Made in Sweden or simply Sweden. I think that the burners made after 1976 are simply marked Optimus

    Flame rings made after 1976 are simply marked Sweden Sweden and this change probably applied to flame rings made between 1969 and 1976.

    Whilst that was when the changes should have taken place there would be a stock of parts with the previous making on them so there could be an overlap of dates.


    Regards Bryan”

    Best Regards,
    Kerophile.