Optimus 5RAM

Discussion in 'Optimus No:5 (inc. S & J)' started by Rangie, Apr 22, 2019.

  1. Rangie

    Rangie Subscriber

    Jul 25, 2012
    Caithness, Far North of Scotland
    Partially sticking my neck out on this one, I have resisted posting it until I had done a bit of research to back it up, it's not just another of my Frankensteins, please bear with me…..

    This was a project from last summer but I thought I would post in in light of the April 2019 SotM Alcohol competition. :D

    I refurbished a 209N Burner in THIS thread and wanted to put it to use as mentioned HERE.

    I thought it would be very useful in a “Household” stove application for powercuts etc.
    It would be stable, have a reasonable power output, have a single operating/priming fuel source and wouldn’t smell greatly in operation or in the event it leaked (also easy to clean up spills, etc).

    In any event, I rather remarkably picked up a clean and late Optimus No.5 at a local sale for £10 and thought that would be an ideal candidate for the potential “Frankenstein”. I could not find a date on it anywhere, not a great surprise. :(

    Comparing the burner heights, my 209N is as near as dammit the same height as a No.5 regulated burner, excellent! You got a late model Optimus 5R Stove as mentioned in THIS 1985 catalogue so it wouldn’t be much of a stretch to make it look vaguely original… :whistle:

    Interestingly enough in THIS 1972 catalogue, reference is made of the transition from the older Optimus No.7 regulated stove to the Primus 5R, however Optimus 5Rs are sold later on.

    (Now some thoughts, if the transition were to go from the Optimus 7 to Optimus 5 I could understand that, mainly to cut costs as the 5 and 7 appear identical apart from the tank fount designation stamping, the Primus side-step is a little puzzling).

    In terms of images, theres a nice image of the No.7 in THIS 1934 catalogue. Optimus 5Rs do appear later, such as THIS one.

    Now, there is Primus example 5RA HERE, and the designation is noted in THIS 1971 catalogue, using the Primus 4150 Alcohol Burner.
    There is also THIS stove here, unsure of its manufacturer/provenance, it may have been an original but missing the alcohol caps so they put a standard (or Burmos?) No.5 silent on it to sell, dunno.

    I scoured the catalogues to see if an Optimus alcohol version was used in a household application. I know they were used in marine/camping stoves like the 45A, 155A, 535A, etc.

    Checking out THIS 1974 Optimus burner catalogue, BINGO!
    Under applications for the 209N, “Alcohol burner, regulable, with automatic cleaning device. Silent type. For boat stoves 155A, 535A and 5RAM”.

    No Frankenstein designation required! An Optimus No.5 with a 209N Burner was offered from at least 1974.
    5RAM – No.5, Regulable, Alcohol, Marine. Would be my educated guess.

    (As an aside, and to tie into my thoughts above, is it feasible that the Primus 5RA and 5R was offered until 1974 with the 4150 and 4195 burners respectively, then discontinued in favour of the Optimus 5RAM and 5R designations with the 209 and 207 burners? Perhaps to use up Primus

    Try as I might, I cannot find an original image of an Optimus 5RAM stove or installation. I imagine it is a standard No.5 mounted in a gimbal arrangement like THIS or merely a 5R supplied with an alcohol burner for you to do whatever you want with in your boat!

    So, here is my version. Not an original example but built-up in good faith to be as genuine a representation of the type as I can determine.

    The only thing I’m sure is incorrect is the filler cap. I think it should be the SRV-fitted type as opposed to the plain type. When I source one of these caps, it will be fitted to the stove.
    N.B.: A Forum member has offered to send me a NOS one :D:thumbup:

    The 1975 catalogue HERE states that the 5R comes with a Tank Lid Safety Valve. The 1972 and 1956 catalogues state that its predecessor (the No.7) comes with a Safety Valve.
    THIS 1974 5R is fitted with one, as is THIS 5RM, and all of the No.7s in the GALLERY.

    (As a point of interest the Optimus 7 wasn’t fitted with an SRV in 1939).

    I’m not trying to falsify anything but if anyone has extra information or photos to vindicate or discredit my theory/build, then it’s an excellent opportunity to boost the photo gallery and catalogue archives! Hint, Hint, Hint….. ;)

    I like it! It works great, but as with all alcohol burners the power output is a little less than Kerosene. My simplex kettle (thanks @igh371 ), is a good pairing to try and absorb as much of the heat as possible! :thumbup:

    Enough writing, here are some photos....... :roll:

    I threw it together to see how the burner height worked, found an Optimus trivet and made dinner with it one evening for an experiment:





    Recently, I dismantled it and cleaned/painted it up. It was given a cursory polish to remove previous stains and corrosion:








    I assembled it again and gave it a run:








    So, there you go, I'll post action-shots occasionally as it is used :D:thumbup:

  2. Afterburner

    Mar 13, 2014
    Comprehensive study of model & set of pictures! :clap::thumbup:
  3. presscall

    presscall United Kingdom Subscriber SotM Winner

    Aug 25, 2009
    Great work and research Alec.

  4. ROBBO55

    ROBBO55 Subscriber

    Oct 27, 2014
    Somersby, New South Wales, Australia
    Excellent post and the stove looks good too! :thumbup:
  5. Harder D. Soerensen

    Harder D. Soerensen Denmark Subscriber

    Oct 24, 2017
    Great and well documented post!
    I like that it runs on Alcohol (like me ;))