Handbuilt Tilley CS56 Outer Cap

Discussion in 'Fettling Forum' started by BernieDawg, Mar 24, 2011.

  1. BernieDawg Banned

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    Hola fellow stove fanciers

    Recently I was asked if I could build a replacement outer cap for the Tilley CS56 stove. This is an amazing stove in my opinion as it has fascinating burner features. Perhaps I'll find some time to post a photo set of the unique burner at some time in the future.

    The request for the outer cap was quite timely, as I had just taken delivery of one of these very interesting stoves not long before. Luckily, mine came with the outer cap so that I had something I could model my construction on.

    For those not familiar with the stove (and because I failed to shoot a pic of it) here is a link to Ian's lovely example which appears to be identical to mine (except his is cleaner and much more presentable):
    https://classiccampstoves.com/posts/102871

    The cap on the CS56 fits into a machined depression in the burner head so it's inside and outside diameters must be exact to fit in this space. I was able to locate some 1 3/4" outside diameter 4130 alloy steel tubing whose inside diameter was exactly the same as the actual Tilley cap: 1.62". The outside of the Tilley cap is 1.70" in diameter, so I machined the fifty thousandths off a short section of tubing on my baby lathe. Sorry, no pictures of this process.

    So, we pick up at the drilling of the cap after a lid has been silbrazed to the tubing section.
    1300926329-IMGP7730.jpg
    This is a 3mm x 3mm grid pattern. The holes are spaced 3mm apart but offset 1.5mm every other row. The drill size is a #53 (0.0595" or 1.5113mm) as measured using the drills as go-nogo gauges. Normally I would say this size hole is too big and will result in flamelet collapse and underburn at low flame (simmer), but Tilley addressed this issue by using wire mesh inside the cap. There are nine groups of 15 holes for a total of 135 holes in the cap.

    After the holes were drilled I wanted to dome the cap slightly to more closely match the subtle doming of the Tilley cap.
    1300926770-IMGP7732.jpg 1300926778-IMGP7737.jpg
    Those of you who have my silent caps may notice that some of the caps are domed and some are not. I've found that the doming can allow more air to mix in the fuel/air mixture in cases where the cap runs rich. The photos above show how I dome a cap, a procedure I call "pooching" for no real rational reason. :lol:

    Here are the two caps side by side to show the effect of the "pooching".
    1300927071-IMGP7740.jpg
    The copy cap on the left is slightly taller, but in a moment I'll trim it's base on the lathe to exact height.

    1300927254-IMGP7743.jpg
    I managed to find the exact size of screen used in the original Tilley cap available in stainless steel through McMaster-Carr here in the US.

    And, here are the original and finished caps in situ for comparisons.
    1300927401-IMGP7744.jpg
    Original
    1300927412-IMGP7745.jpg
    Copy
    1300927425-IMGP7752.jpg
    Original
    1300927439-IMGP7760.jpg
    Copy

    1300927632-IMGP7766.jpg 1300927641-IMGP7768.jpg
    I'm guessing the logo will tell you which is which. ;) What are the little notches for, you ask? I have absolutely no idea since they don't seem to fit in any depressions in the burner or in any other way affect the performance of the cap. I put them in anyway with an abrasive cut-off wheel and a tiny needle file to match the original.

    That's it. Thanks for viewing. Hope this was interesting to some of you.
    Cheers,
    Gary
     
    Last edited by a moderator: Jul 1, 2015
  2. hikin_jim

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    Most impressive. A beautiful re-manufacturing of the original, with great authenticity. Top marks, Gary.

    Now, if I may ask, what is the purpose of the wire mesh outside the burner? I don't know that I've seen that before. Is that to conduct more heat back to the burner.

    And, if I may ask, how does the mesh inside the burner help prevent underburn?

    HJ
     
  3. Knight84

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    :shock: Wow Gary!!! Your the Man!!!

    I am glad my CS 56 came with a cap too but it is good to know there is such great talent out there. As always your attention to detail is fantastic.

    I was wondering what the notches are for too. My guess is it has something to do with the holes. As the notches match the hole pattern. Most likely for lining up on a machine.

    Wonderful work again and thank you for sharing. I look forward to seeing your CS 56 added to the site as well.

    Cheers,
    Jeff
     
  4. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi Gary, masterful work. You are a great stove fettler.
    Best Regards,
    George.
     
  5. loco7stove

    loco7stove Subscriber

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    Hi Gary

    The master at work again, very impressive work to which we all aspire, need i say more :clap: :clap: :clap: :thumbup:

    Best regards Stu :thumbup: .
     
  6. steve coomber

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    a bit bulky to fit in my back backpack but still my favourite stove burns hot and simmers well. Runs all week on a litre of fuel. Nice resto how about a generator next. i have been trying to get one for a few years.
     
  7. mr optimus

    mr optimus Subscriber

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    Hi Gary out standing work you have done on the burner cap beautifully engineered infact it looks better than the original and works just as well
     
  8. Big BTU

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    Hi Gary,

    another beautiful cap for a classic! Out of curiosity how much time goes into each cap roughly?
     
  9. BernieDawg Banned

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    Thanks for the accolades gents. :)

    John, the caps I sell with the integrated inners and legs and all run about seven hours. The Tilley cap probably took almost that long, too, because of the weird drilling pattern, the machining of the outer diameter and the cutting/filing of the notches. Cut out the special features and it would have been closer to two hours. I'm not a fast worker (or thinker) and new/different stuff always slows me to a crawl so I don't goof up.

    Cheers,
    Gary
     
  10. dikman

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    Nice work, Gary. Clever method of doming the top, although I would be reluctant to try it after soldering - with my luck I'd pop the soldered joint!

    Interesting hole pattern too.
     
  11. Rick b

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    Hi Gary, Excellent work. (I seem to be late with these things)...and what George said.
     
  12. johnsnz

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    The notches could well be part of the original tooling for the production of the cap by Tilley.

    The notches seem to 'line up' with each group of burner holes. Maybe they produced the original holes on a broach and the slots are to index the cap around on a fixture for the correct spacing.


    Gauze or mesh really interfears with flame in a big way flame struggles to penetrate it. By lining the cap with gauze lightback is prevented.
    Look at a ported style burner on a propane stove chances are it will have a gauze flash back liner.

    HTH
     
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  13. kerophile

    kerophile United Kingdom SotM Winner Subscriber

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    Hi, John is quite correct on the effect of fine mesh on a flame-front, It acts as a flame-arrestor and is the basis of the Davy Safety Lamp:
    http://en.wikipedia.org/wiki/Davy_lamp
    Best Regards,
    Kerophile.
     
    Last edited by a moderator: Jul 1, 2015
  14. David Shouksmith

    David Shouksmith Subscriber

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    Well, obviously it's because you're a bit of a 'dawg', Gary! ;) :lol:

    Fantastic work! :thumbup: - I'm almost sorry my CS56 came with the burner cap in place... :p
     
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  15. BernieDawg Banned

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    Thank you David! I like that explanation much better than the one that my spouse proposed. She said, "Oh! 'Pooching' is making them bulgier. Kind of like your waistline getting 'poochier' from drinking all that beer."

    Hrumph. :roll: :lol:

    Cheers,
    Gary
     
    Last edited by a moderator: Jul 2, 2015
  16. steve coomber

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    how do you get the burner cap off does it just pull off and i dont think mine has the mesh inside it got it outside. it burn hot that's why we use it as a wok burner to cook our stir fry