Petromax 826 fettling help needed

Discussion in 'Fettling Forum' started by Bjorn, May 18, 2023.

  1. Bjorn

    Bjorn Norway Subscriber

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    I finally decided to have a go at refurbishing this petromax 826. Im a pressurelamp-noob, so maybe you guys can give me some guidance :)

    It has been sitting in a basement since my grandfather passed in the 60s.. This is a pretty corrosive environment, and the lamp show signs of this. The inner hood (?) is badly rusted. Is it possible to find a replacement that fits?

    What replacement globe and mantle will fit this stove?

    The rest of the lamp looks to be in okay condition. The adjustment knob turns freely, and the cleaning needle pokes out when knob is turned. Pump assembly looks to be in good condition.
    20230518_105741.jpg 20230518_123958.jpg 20230518_123932.jpg 20230518_123942.jpg 20230518_123920.jpg 20230518_124031.jpg
     
  2. Sellig33

    Sellig33 France Subscriber

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  3. JEFF JOHNSON

    JEFF JOHNSON United Kingdom Subscriber

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    Welcome aboard!:thumbup:
     
  4. eiremax

    eiremax Subscriber

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    Potential is there! Parts readily available. Look at the bottom of the tank, there may be a code scratched into the base similar to what was done with earlier Petromax lanterns. Your regular 829 globe will fit as will any 500HK mantel. (I use Helox). I presume you are doing a complete strip down and clean? Plenty of resources on YouTube that can show you the process better than I can type it! If you have access to an ultrasonic cleaner that would make your life easier
     
  5. eiremax

    eiremax Subscriber

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    Oh Martin at Starklichtlampe or the lads at Stuga Cabana for parts.
     
  6. Bjorn

    Bjorn Norway Subscriber

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    Thank you all for the helpful replys :thumbup:

    I will do a complete teardown and cleaning. I dont have access to a ultrasonic cleaner, but i guess a citric acid solution bath will do.

    Looks like I can get most replacements parts from the sources you guys provided. But I cant figure out what to do with the inner burner hood. Do i need a new replacement piece (part p117) complete with mixing tube and burner? Or try to fix the one i have?
     
  7. Fireexit1 United Kingdom

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    The mixing tube/burner are brass so should be OK. I would look for an inner hood. A new one or a second hand one would do. Others will confirm but I think the 826 and 829 ones are the same.
     
  8. eiremax

    eiremax Subscriber

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    Should have no problem in finding a European made hood, ie. From Petromax, Geniol or Hipolito. The inner hood you show is identical to my prewar 2826. If you want take a measurement of its outer diameter along with the height of the rim. I can double check interchangeability for you with that of the above mentioned brand hoods. No harm in checking just to be sure.
     
  9. Bjorn

    Bjorn Norway Subscriber

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    Update!

    After some time spent tracking down parts and a bit of fettling, this 826 was brougt back to life. A few soaks in a citric acid bath, a new filler cap gasket, new globe, and a new inner hood, new mixing tube, a spindle gasket and new pump leather made it light up again.

    The nickel plating is almost completly gone on the collar, but still mostly intact on the fount. The top of the hood has at some point been fixed. I kinda like the rustic look it has now.

    The old inner hood was completly rusted trough multiple places and had to be replaced. I bought a used complete inner hood. I dont know wich make this is, but the place i bought them sells both surplus primus 1082 and optimus 300/350 lamps. So i guess its from one of those.

    My plan was to mount the original mixing tube in the replacement inner hood, but i soon found out that the mixing tube was in bad shape and couldnt be used. The inner hood i bought had a mixing tube with an ajustment screw. This screw made the hood not fit properly, so i had to replace this aswell. Luckily i found a compatible mixing tube.

    Im curious how old this lamp is, it i possible to date it based on the pictures? I have not been able to find numbers on the bottom of the fount.
    20230615_123930.jpg 20230615_202145.jpg 20230608_210441.jpg 20230608_210301.jpg 20230608_210256.jpg 20230615_202208.jpg 20230615_123930.jpg 20230615_202145.jpg 20230608_210524.jpg 20230608_210301.jpg 20230608_210256.jpg 20230615_202208.jpg
     
    Last edited by a moderator: Jun 15, 2023
  10. Fireexit1 United Kingdom

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    Good works Bjorn. All here would agree that you have done well and that the lantern was worth the effort ! The "patina" only serves to tells the story and age of the lantern. It should be burning brighter - maybe it needed more pressure ? - the manual says 60-70 pumps.
    As to age I would guess it is is pre-wwII but others here are more expert on Petromax dating.
     
  11. Bjorn

    Bjorn Norway Subscriber

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    Yea, i guess its not shining as bright as it should. (But the picture is "lying" somewhat). I left the original jet, wich has number "3" stamped on it, in the lamp. Currently it has a 350cp mantle. I will try to pump some more :)
     
  12. Fireexit1 United Kingdom

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    The mantle does look a little small, - but not far off. It should still give a white(ish) light - but appreciate it will look better in the dark (and cameras/PC screens do funny things to colours). Many 350 mantles are the same as 500cp ones (I use the same mantle on an Optimus 350 as I do on the 500). They seem to end up +/- the "correct" size on the first firing. The 826 is a 350cp lantern apart from the later E model which had 450 written on it. Keep going :thumbup: - you have done very well indeed for a first outing into this world.:clap:
     
  13. WimVe

    WimVe Subscriber

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    As for the light: you have a new inner hood and J-tube so make sure the distance between the top of the jet and J-tube entrance is ok for the 350 or 500cp jet it should be 14,2mm.
     
  14. ROBBO55

    ROBBO55 Subscriber

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    Bjorn, it's cleaned up nicely, congratulations :thumbup:
     
  15. MYN

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    A very nice restoration job. Getting the lantern to attain its highest light output might require some tinkling (adjusting the fuel-air ratios by means of the air gap between the jet and the J-tube inlet, paddle at the j-tube if present, using different mantles, etc). This is one of the fun of all Petromax-styled lanterns.
    It would be hard to guess the manufacturing date without knowning what had been inscribed/scratched at the fount's bottom. Those dating from the 1960s and later would have numbers stamped at the fount's bottom plate. Your lantern mostly has typical constructional features of the pre-WWII Petromax 826 design...especially those made in the late 1930s /early 40s.
    However, both the hood and inner hood designs had undergone some transitions. Instead of having 2 capture screws at the top cap of the hood (earlier design), the single-piece hood of your lantern has more resemblence to those of later Petromaxes (post-war and modern). They are not exactly identical to modern hoods but the features are close enough. These can sometimes be found on lanterns dating from the late 1940s till early 50s. During this time, the Graetz factory at Altena, Germany was still new, and perhaps products were still using the earlier E and G (Ehrich & Graetz) designs.
    @Reinhard might have more samples with exact features resembling those of your lantern.
     
  16. Reinhard

    Reinhard Germany Subscriber

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    Unfotunately I have a chronological hole in my collection from 1930 to 1936,so I can't look it up.The hood cap was put together by someone himself.Except for one variant of Petromax900,as far as I know there are no other Petromax with only one screw for fastening the cap.
    The hood has only 4 bars. The carburetor is already in 2 parts.The inner case looks strange for me ,it has features that I don't know from Petromax.
    The J-tube does not have enough threads to properly attach a mixing chamber to it.
    Please clean the bottom of the tank with cleaning polish.Perhaps you can find tank scratches there that can be used to identify the age.

    Kind regards,Reinhard
     
    Last edited: Jun 18, 2023
  17. Bjorn

    Bjorn Norway Subscriber

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    The distance between the jet and mixing tube is correct according to my petromax-tool. I will try to adjust it until it gets just right O:). Does a yellow tint suggest a too rich fuel/air mix caused by a too short gap between the jet and mixing tube?

    I took a picture of the lamp in my dark, not wery tidy shed. More white tint this time. Since this is my first pressure lamp, i have no idea how bright they are supposed to be :-k.
    20230617_123800.jpg

    The inner hood is a replacement, as is the mixing tube. The original mixing tube broke when i tried to remove it from the inner hood. It was so corrodet that i using very little force litteraly tore it in half :whistle:.

    I looks like the cap on the hood has been corroded in such a way that there is a big hole in it. My grandfather apparantly fixed this by riveting a piece of metal on top of the cap, and one inside the hood, sandwiching them together. It may have had 2 screws holding the cap to the hood originally.

    I will do another search for numbers on the bottom of the fount :D
     
  18. Fireexit1 United Kingdom

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    The colour looks fine - it is difficult to tell from a photo but I think it could be a little brighter. I use a lux meter installed on my I-Phone - it probably does not tell the truth in relation to the actual brightness but it can be helpful when comparing before and after moments..
     
  19. MYN

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    A yellow tint can also be due to the mantle composition. If you've replaced it with a modern mantle, it could well be yttrium-based. The older radioactive thorium-based mantles usually, but not always, give a 'whiter' tint. That in turn can make it appear visually brighter(eye perception) but not necessarily brighter in the actual sense (by lux measurement).
    You can also try adjusting the air gap higher than the normal 14.2mm to see if there're any further improvements. That's provided there is still allowable threads and room in both the j-tube and its mounting within the hood.
    Besides that, see whether a few more strokes on the pump(slightly higher pressure) makes it brighter or yellower. If it starts to get yellower or sooty, then you know its due to improper fuel-air adjustment.
     
    Last edited: Jun 22, 2023
  20. WimVe

    WimVe Subscriber

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    First picture is defenitely a not well burning lantern in my opinion.
    The last one is better.

    There can be several reason for this fro dirt to worn parts.
    That is why I always say that you must understand how the lantern works so you can identify problems but more over, can fix them.
     
  21. Bjorn

    Bjorn Norway Subscriber

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    Thank you all for the helpful comments and feedback, I appreciate it a lot.

    I finetuned the gap between the jet and j-tube and gave the vapouriser a proper kleaning. I am satified with the brightness now.

    Fettling is fun it turns out. So much fun that I have 3 more lanterns. Another px 826, a px 828 and a radius 103.
     
  22. Fireexit1 United Kingdom

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    Welcome to the club !:D/
     
  23. Bjorn

    Bjorn Norway Subscriber

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    I took another look at the bottom of the fount and numbers appeared :content:

    I read them as 11 6. So november 1936?

    20230722_194558.jpg 20230722_194613.jpg
     
  24. Bjorn

    Bjorn Norway Subscriber

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    Ah, got the pics mixed up. It is 7 7, so july 1937?

    The lamp from the post above is going to be another thread ;)

    20230719_111344.jpg
     
  25. MYN

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    It is common or typical that numbers are handwritten or scribbled in the following way in Germany and Austria:-
    20230811_221418.jpg
     
  26. Reinhard

    Reinhard Germany Subscriber

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    @Bjorn
    You got the numbers absolutely right.The first number is 11 6 = November 1936 and the second is 7 7 = July 1937.
    Thanks for showing this numbers.I just checken my Petromax 827 from 1937 and the numbers are so bad there too.11 7 = November 1937.
    IMG_20230812_122523.jpg
     
  27. Bjorn

    Bjorn Norway Subscriber

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    @Reinhard
    Yes, the numbers are pretty faint. I zoomed in a bit here to make them more visible:
    20230719_111344.jpg

    The numbers on my 828 stand out very clear in comparison:
    20230705_203755.jpg
     
  28. Reinhard

    Reinhard Germany Subscriber

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    The numbers aren't always weak,but what bothers me is that they look more like Norse runes than Arabic numbers.But I can read them.The last numbers are 9 7 = Septemper 1937.
     

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