1949 date Primus 702

Discussion in 'Primus No:702' started by presscall, Nov 12, 2012.

  1. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    Masterly, George. I'm sure I've seen that table you produced before but promptly lost it and should then have put it in my 'favourite topics' folder as I've done now.

    Theory apart, I regularly use a Primus 85 (as a wok cooker) and though physically smaller, this Primus 702's burner does seem as hot or very nearly so.

    That said, I think I'll repeat the experiment and take more care with the 'dipstick' reading.

    Thanks again George.

    John
     
  2. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    I took a look at the pump cap tonight, showing the consequences of much use

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    I'd some brass tubing of the right bore handy ...

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    ... and silbrazed it in place, the silbraze filling the gaps pretty well

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    Cleaned up ...

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    ... installed it on the pump shaft - incidentally, that's a quality replacement pump washer on there from maestro and CCS member Sefaudi - thanks Sefa!

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    ... and installed the assembly on the stove

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    Next job's repairing the primer cup, which has a chunk scorched out of it as a result (we think, eh Brian?) of a jobbing plumber who took a blowlamp to the burner to pre-heat it

    1353621631-44.JPG

    John
     
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  3. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    That primer cup and the damage to it again

    1353706625-45.JPG 1353706640-46.JPG


    I cut out the damage (Dremel cutting wheel) and made a patch piece from a thicker gauge of brass sheet. I hammered it into a channel shape, which together with the extra thickness of brass I knew would give me most opportunity to reproduce the contours of the primer cup at the final machining stage

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    Here it is just after silbrazing, with the flux yet to dissolve off in boiling water

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    Flux gone and after a session in an ultrasonic cleaning bath - mild vinegar solution/detergent rinse/clean water rinse - it's more obvious how the silbraze has flowed around the joint

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    I'll see if I've time tomorrow to get the component finished off.

    John
     
    Last edited by a moderator: Jun 27, 2015
  4. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    There was some talk recently in a post from Nick about his Primus 110 burner repair about supporting work for brazing.

    This was the arrangement I used for this particular job - cast iron skillet, shards of earthenware ceiling tiles to insulate the workpiece from the skillet (preventing conducted heat loss from where it's wanted) and to support the workpiece. It's also clear from the picture sequence why I kept that 'tail' of brass on the brazed-in insert, so that I'd be able to hold the piece in place by trapping the 'tail' between a couple of tiles

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    John
     
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  5. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    Primer cup cleaned up using a Dremel with abrasive drums/tips/cutting wheel. Nothing fancy but with a not-too-obvious repair

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    The stove's certainly usable now, with just a pair of carrying handles to fabricate and solder in place on the fuel tank

    1353766531-58.JPG

    John
     
    Last edited by a moderator: Jun 27, 2015
  6. shagratork

    shagratork United Kingdom Moderator, R.I.P. Subscriber

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    John

    So the fettling saga finishes.
    The fact that you have fettled that lovely old Primus 702 is all to your credit.
    But it is what you had to do and the way you did it that really impresses me.
    A superb job.
     
  7. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    Thanks Trevor.

    Thanks too to the donor who kindly gave me the stove!

    John
     
  8. snwcmpr

    snwcmpr SotM Winner Subscriber

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    Very nice work John.

    Ken in NC
     
  9. Rangie

    Rangie Subscriber

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    Hello John @presscall , sorry to dig up an old thread.... :whistle:

    Is the 702 at hand so you could measure the dimensions of the flame ring for me please?
    I have a shadow of a 702 I'm beginning to work on.. :lol:

    Was there evidence of a handle/handles on your example? Mine is also missing a handle(s)

    It is rather battered, over-soldered and has a pump handle from what looks like a Sievert Blowlamp but it'll come good! Photos anon :content:

    Alec.
     
  10. presscall

    presscall United Kingdom SotM Winner SotY Winner Subscriber

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    @Rangie

    Hi Alec. The flame ring measures 52mm outer diameter and 56mm height. Thickness of the cast iron of the cylinder is 3mm.

    The stove would have had handles, like Nick's example HERE, but only a solder residue of the hinge attachment remains.

    John
     
  11. Rangie

    Rangie Subscriber

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    Great thanks! :thumbup:

    Alec.
     
  12. Andrew

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    @presscall .
    Hi John .
    Congratulations on a well fettled stove. I have just acquired a 1948 702 minus the flame tube. Would it be possible for you to give me the dimensions of the original to make it possible for me to make one for myself.
    Thank you.
    Andrew
     
  13. Wim

    Wim Subscriber

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    Hi @Andrew , two posts above yours John gives the measurements of 52mm outer dia, height of 56mm and thickness of 3mm.
    On both my Sievert heaters I have used seamless pipes of the closest size I could find, also exhaust pipe of close dimensions can be used.

    Best regards,

    Wim
     
  14. Andrew

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    @Wim . Oops. A quick glance over the posts this morning and I missed that. Thank you. Andrew