Optimus 8 case hinge

Discussion in 'Fettling Forum' started by snwcmpr, Apr 13, 2016.

  1. snwcmpr

    snwcmpr SotM Winner Subscriber

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    I am embarking on the repair of an Optimus 8 case. Both hinges, for the front flap, are broken off nearly flush with the cross pin. I imagine it had rusted stuck to the pin, and the owner pulled it down until it bent/broke the metal.
    I plan to sil-braze (2) tabs to the flap and fold them around the pin. I will lose the paint, so the case will be bead-blasted and painted Charleston Green.

    I tried to measure the flap thickness but I measure .025" (.635 mm) to .033" (.8382 mm) thickness.

    I have searched here, but did not find anything like this. If you know of a link to an Optimus 8 hinge repair, that would be helpful. If you know the flap/hinge material thickness, that would be nice, too.

    Ken in NC
     
  2. snwcmpr

    snwcmpr SotM Winner Subscriber

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    As I went to the shop to take some photos, I realized I could possibly sil-braze the pieces back onto the flap. More about that later, I have gravel to shovel first.

    Ken in NC

    Optimus 8 Flap 001 - Copy.JPG Optimus 8 Flap 002 - Copy.JPG Optimus 8 Flap 003 - Copy.JPG
     
  3. idahostoveguy

    idahostoveguy R.I.P.

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    Ken,

    I didn't realize you were talking about such a bad break in the hinges. Might be better to cut back some of the door metal and put new stock in. There's a lot of rust that may keep the silbraze from holding. I'm sure you could then silbraze or weld new pieces on and then work the weld down to something not noticeable. I've done a similar repair on a car fender where I cut out the rusted area, then replace with same gauge sheet and weld it in. After a little grinding and sanding, the repair is not visible with a good coat of paint. Just a thought though.


    Here's a video on doing stitch welds on sheet metal. It may or may not help, but, just to illustrate the concept:

     
  4. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Thanks Sam.
    I tried a sil-braze. It stuck a little, and also not. So, not a complete bond.
    I am back to the 'cut and replace metal', as you said.
    No harm YET.
    (No photos of this part, no way I show the world my errors) :)

    Ken in NC
     
  5. snwcmpr

    snwcmpr SotM Winner Subscriber

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    (Photos later)
    I cut off the tabs and added .030 steel replacements. I ordered steel from amazon. Silbrazed on it is strong enough to bend the tabs for the rod. I got the bead blaster working. The flap is clean.

    Will J B Weld or Permatex Cold Weld hold up on the flap, under Rustoleum paint? I want to fill the holes after final bead blasting.

    I searched but did not find any real results of case hole patching.

    Ken in NC
     
  6. Afterburner

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    Are those through holes (in one metal layer) or are they holes on one metal layer(case) but there is another metal layer(new hinge flap) under that?

    If there is a hole in one metal layer and there is another metal layer under that it might be possible to fill the hole with tin/lead solder (especially if hole and surroundings are sand/glass blasted that they are free of rust/dirt). Excess solder is easy to wipe off when solder is still in fluid form.
     
  7. Funfundfunfzig

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    If you have a MIG welder you can dial the power right down and do little "stitches" on very light gauge steel until eventually you have a complete seam. Allow plenty of time to avoid getting too much heat that will buckle your job or worse still blow a hole.

    if you don't want to try a butt join you could make a new little hinge piece and weld, brazen or solder it in place. They're under the tank so out of sight.
     
  8. snwcmpr

    snwcmpr SotM Winner Subscriber

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    @Funfundfunfzig Thank you but I have the tabs on so I don't need to butt join, I don't have a welder either.
    I just need to fill small through holes for cosmetic reasons.

    @Afterburner Not sure what you mean about layers. The flap looks to be one layer of steel.

    I just want to know if the cold weld material will hold up over time.

    I will try solder.
     
  9. snwcmpr

    snwcmpr SotM Winner Subscriber

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    As it is today.
    Much more to do.

    2016-05-04 20.21.53.jpg
     
  10. Funfundfunfzig

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    Looks like it's coming along nicely!

    I don't think you'd have any problem filling small imperfections with a metal repair product particularly if you're going to paint over it.

    I recently had a door repair to do on one of my 8r's that had been dropped on the front corner causing the door to jam. This was overcome by the PO bending the flap. I carefully unrolled the hinges just enough to unhook the flap as the hinge pin was too long to remove. I did a tiny panel beating job to reshape the damaged corner and flatten out the flap.

    I was worried about breaking off the hinge sections when refitting the flap.

    As a precaution I heated and quenched the very edge of hinge area to anneal the metal and was able to roll the metal hinge section back around the pin without further damage. I lost a bit more paint of the flap but you'd hardly notice!

    Here's before...

    image.jpeg

    And after the repair...
    image.jpeg
     
    Last edited: May 5, 2016
  11. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Looks good.
    The quenching of the steel case would harden it. To anneal I would let it air cool.

    I may get time today to continue.
     
  12. Robert Bruce

    Robert Bruce SotM Winner Subscriber

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    Only hardens if it has carbon or some other in it, don't think it would be able to harden. The heating of steel then quenching or letting it cool slowly will do nothing if it is just steel. A big but, old steel made before the war I think may have some impurities in it that may cause hardening ??????

    Cheers
    Rob

    PS, you can heat steel that has a certain hardness and keep it that way if you only go to black heat and no more.
     
  13. Funfundfunfzig

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    I gave the tabs on the door a few very gentle licks with the oxy-acetylene torch to just get them red. Then wiped over with a wet cloth. Probably didn't make a lot of difference but if I'd broken the tab off I would have wished I'd done it!

    This how I've approached old car sheet metal and it seems to help.
     
  14. Robert Bruce

    Robert Bruce SotM Winner Subscriber

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    Oh yes, hardening and tempering steel is an art in it self. A couple of degrees either way will cause greaf, usually takes some experemting, the quenching that is, water temp , oil ect. Can be done but best to leave it to an expert.

    Cheers
    Rob
     
  15. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Yes, if it has at least .03% (or is it .3?) carbon. Steel is iron with carbon. If the steel is 1030 but less than nominal (but still in spec, like .028) it won't harden, so my teacher suggested using 1035 to ensure enough carbon for hardening.
    Here, we do not know what steel they used. So, I would not quench if I wanted to avoid hardening.
    Tempering is, as I understand it, used after hardening/quenching to keep it hard but remove any brittle, or over-hard, qualities, by bringing it up to a certain temperature after quenching, then air cooling.

    Ken in NC
    (Not a metallurgist, just a few things I remember from my brief schooling)
     
  16. Robert Bruce

    Robert Bruce SotM Winner Subscriber

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    Ken , you are correct, I was not going to put the detail in my post.
    This is an interesting subject, I too did a bit on it at school in mettle work, then in later life secerched more, mostly in relation to forge work. My early attempts were all greaf , mostly too hard in fact brittle, later I got somewhere near what I needed.


    Cheers
    Rob
     
  17. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Cheers back to you.
     
  18. Funfundfunfzig

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    @snwcmpr
    How's the 8r going anyway? Your post was never about metallurgy and I think I took things down a rabbit hole!
     
  19. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Thanks for asking.
    I have been slowly bead blasting the case. My air compressor will not keep up with the blaster cabinet.
    It is riddled with holes and rusted through in small spots. It will not be a 'Pretty Stove' as there are a lot of places that show pitting, too. I have therefore decide I will not work too hard at smoothing the surfaces. It will be an original color, Rustoleum Charleston Green as I received from BD when I got my first Optimus 11 from him, my wife bought me a b-day present a few years ago. I will use a white primer that can be used with rusted metal.
    I soft soldered some holes, and used some high temp 'steel weld' LINK & LINK. And that is curing for a day, and will let it cure more before I sand it. I've not used it before, and know the bottom of the case gets warm (not hot), so I didn't want to use JB Weld.
    I have assembled the pieces, closed the hinge 'flaps' and the front door works quite well. The sil brazed pieces are holding very well.
    ATTENTION: If you read this and are assembling your flap onto an Optimus 8.... Do Not Straighten the Rod that is used in the flap hinge. That very slight bend allows the flap to hold its place when closed. It seems to have a bit of tension for the door. I had thought about straightening it, let it be, and the flap works very well.

    Ken in NC
    (More later)
     
  20. Funfundfunfzig

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    Hi Ken

    Ive left my rough 8r in its raw state for now. I had gone so far as purchasing some paint for it but postponed any further work in favour of fettling a Primus 535.

    I'm keen to see how yours turns out as I'm still thinking I'd like it to be a more well presented stove.

    I did think about pulling out the hinge rod to straighten it at the same time as fixing the door but gave up after I found it didn't come out too easy. Glad I didn't do that now. I guess it acts like a little torsion bar to hold the door shut. Clever!