Optimus 111 T refurbishment

Discussion in 'Fettling Forum' started by Twoberth, Jun 13, 2019.

  1. Twoberth

    Twoberth United Kingdom Subscriber

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    I bought this stove for £30 off the internet, buyer collects. The seller was only 20 miles away so it was a bargain.
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    These are some of the details of my refurbishment. I have omitted photos of internal components of the 111 as these have already been included in other fettling post for this type of stove.

    This is not a particularly old stove, and after rinsing the tank and replacing the filler lid washer, the stove was pumped up and pressure tested. The SRV was checked to make sure the spring still had some ‘spring’ in it, but the release pressure was not measured. The pump piston is an ‘O’ ring rather than a leather, but it was in good condition so I left it alone. The stove held pressure well so I also left the NRV alone.

    A test firing showed that all was well, and then the stove was separated from its case and both were and cleaned. One of the case hinges was broken across its centre pivot section, but the broken bit was still wrapped around the hinge pin and it was easy to clean up the bits and braze back together.

    After I finally got the silent burner outer cap off (it’s the type that locks on with two small tabs), the burner was stripped down. On examination the nipple, pricker rack, packing, washers and spindle were all in good order and so nothing was renewed.

    Case

    The case was stripped using electrolysis with the DC power fed directly from a battery charger. A 2% washer soda solution (230gms of crystals to 5 gal. water) was used and the case was given two 12-hour treatments; one using a circle of wire mesh fencing (the galvanised coating was long gone) for the positive terminal, bent around the perimeter of the bath to give ‘line of sight’ to the outside of the case, and the second treatment using a steel bar in the centre of the electrolyte for ‘line of sight’ with the inside of the case.
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    This worked very well with most of the original paint coming off in small sheets.

    The case was then washed and scrubbed with ‘0000’ steel wool to remove any remaining paint. Then straight into a phosphoric acid bath (the bare case rusts very fast) for overnight soak.

    Stove was then washed and dried, and using automotive aerosol paints given two coats of grey primer,
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    and three coats of black gloss with 1 hour between coats.
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    Then into the Kubex oven heated by a SVEA No.5 for a bake at 100 to 150C (I gave up after 1 hour as it was a pain to control the temperature. I should have waited until the wife went out and used the kitchen oven).
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    Finally two coats of clear lacquer with 1 hour between coats, and after an overnight cure, a light wipe with ‘0000’ wool and a polish with furniture wax.

    Pot stand supports

    The supports that came with the stove were the normal 111 supports, but they were badly tarnished and one was cracked so I decided to make new ones from 4mm 303 stainless steel rod. Type 303 stainless steel is a high sulphur content free machining alloy and doesn’t have the same ductility as other stainless steels, so the double bends in the uprights were not possible. However, semicircular stops were fixed to the straight uprights with epoxy to obtain the necessary support from the case guide slots.
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    Stainless steel has very poor thermal conductivity, so I don’t expect the epoxy to get hot enough to fail. Finally a home-made stainless steel heat diffuser /simmer plate was fitted to the pot supports, together with the obligatory aluminium (cider can) drip tray.
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    Then a new decal for the tank and a test firing for the cleaned burner were done, and the stove is now on the shelf in line for coffee duty sometime this autumn.
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    This is the first Optimus 111T that I have owned and I am very impressed with the power and control of this silent burner. I was also very please with the result and I couldn't resist these before and after shots.
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  2. snwcmpr

    snwcmpr Subscriber

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    The decal is for a 111B, a gasoline only stove.
     
  3. Twoberth

    Twoberth United Kingdom Subscriber

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    You are correct of course, I stuck the wrong one on. Easily fixed, and thanks for pointing it out.
     
  4. snwcmpr

    snwcmpr Subscriber

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    Nice work.
     
  5. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi @Twoberth . Nice work.
    Thanks for posting.
    Best Regards,
    Kerophile.
     
  6. CW

    CW United States Subscriber

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    very nice
     
  7. Harder D. Soerensen

    Harder D. Soerensen Denmark Subscriber

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    Well done - especially your simmer plate!
     
  8. mortada aljanabi Saudi Arabia

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