Can I scale up the John-Tom Poppin plan

Discussion in 'Plans' started by rlukens, Feb 8, 2018.

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  1. Feb 8, 2018 #1

    rlukens

    rlukens

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    Thinking of building a flame licker. I understand that they can be "difficult" to function. I assume that means bore and stroke must be in proper proportion,...among other things. I like the little Poppin plans that are readily available but I cringe when I see 2-56 tapped holes. Not only do they scare me, but the taps are damned expensive.
    I can see that increasing the stoke by a factor of say 1.5 would not equate to increasing the bore diameter likewise. Perhaps I could increase the bore "area" by 1.5? I don't know.
    In lieu of scaling the Poppin, does anyone know of other vacuum engines on a larger scale?

    TIA
    Russ
     
  2. Feb 9, 2018 #2

    Cogsy

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    Jan Ridders has plans for larger flamelickers on his site that he will happily send you if you email and ask. His site is a great place to check out too (there is a button to translate to English) http://www.ridders.nu/ . His internal valve flamelicker was my first engine and is still the one I have for my avatar image.

    In regards to scaling the Poppin, I would think it would probably work simply scaled by a factor. The internal valve flamelicker I mentioned above was originally designed and built with an 18mm piston but was reworked for a 22mm piston to increase performance, so there is a range over which they will run. Having said that, they can indeed be extremely difficult to get running and if you're trying an unproven design without explicitly knowing it will run, it's very possible you'd give up on it before getting it to function.
     
  3. Feb 9, 2018 #3

    fcheslop

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  4. Feb 9, 2018 #4

    Blogwitch

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  5. Feb 9, 2018 #5

    rlukens

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    Thanks to all for your info.
    Cogsy, I liked Ridder's designs but when I requested prints, I got: "Could not perform this operation because the default mail client is not properly installed.
    Frazer, searched Ernst Bogell to no avail
    John, Ich spreche kein Deutsch
    I seriously appreciate your responses... and this forum. That being said, I think I'll design my own (I enjoy that as much as the build). I'll glean what information I can from other's and stay close to their general parameters.

    Russ
     
  6. Feb 9, 2018 #6

    fcheslop

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  7. Feb 10, 2018 #7

    Blogwitch

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    Russ,

    I speak only enough German to get me to somewhere to eat, sleep and to go to the toilet, but what more than dimensions do you really need to work from his plans. Initially I used Google translate on his site and it did a very good job of letting me know what it was all about.

    All I needed to go was go through the material lists and put in our names for them, after a while, you soon know what you are looking at. BTW, the very large flywheels for his models come from Germany as well, and very reasonably priced, even with P&P.
    https://www.rc-machines.com/en/mode...lying-wheel-cast-iron-o-290-mm-x-45-mm-950-kg

    John
     
  8. Feb 10, 2018 #8

    pjpickard

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    John,
    I don't see a link to plans on Gerd's site. But I know not nearly a lick of German! can you point to a link to plans?

    Thanks!
     
  9. Feb 10, 2018 #9

    Blogwitch

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    Last edited: Feb 10, 2018
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  10. Feb 10, 2018 #10

    fcheslop

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    Thanks for the RC link John
    I can see the relevant parts for the 50mm bore engine
    best wishes
    frazer
     
  11. Feb 10, 2018 #11

    Blogwitch

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    Frazer,

    Glad to be of use to someone

    John
     
  12. Feb 12, 2018 #12

    rlukens

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    John, I had to look it up, but I knew there was a phrase to describe your comment...self-deprecating.
    Come on man, I always appreciate your posts.
     
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  13. Feb 13, 2018 #13

    Blogwitch

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    R,
    Most probably because I haven't actually shown any build posts for a long time, and relying on my very poor memory and my archive to answer questions.

    But all is not lost, I had two very good friends come over last weekend and they managed to get lots of heavy stuff moved out of my shop into storage boxes, allowing me to actually get into my shop without falling over, so expect me to start doing things soon.

    I only have a month of radiography and then I should be given the go ahead by the medicoes...

    John
     
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  14. Feb 14, 2018 #14

    JCSteam

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    First John, it's good news to hear, secondly I've read quite a lot of your previous posts and have learned a lot from them so really please don't beat on yourself like that. Thirdly I'm looking forward to travelling down to your shop sometime this year so you can show me the ropes first hand how to turn a a few lumps of different metals into a beautifully crafted machine fit for a king ;) all in good time of course.

    I have to say though veering back to the topic, that I find this thread amusing in that I recently came across the poppin plans and was wondering how to go about scaling these type of engines. The twin flywheels of the poppin appeal to me :)
     
  15. Feb 14, 2018 #15

    JCSteam

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    You say you cringe at the thought of the 2 56 tapped holes, I'd say just use 8BA as there not far off the same size, and they are just been used for fixings as opposed to a critical thread type as used on steam fittings. There also more likely to be in your toolbox :)
     
  16. Feb 14, 2018 #16

    fcheslop

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    Thats good news John,
    Why not use 2mm sized bolts much cheapness and easily available in Europe. I think I used 10BA on my Poppins as youre tapping cast iron its not to difficult
    One mod I make when building Poppin or any similar engine is to spigot the cylinder into the frame just save faffing about getting the location right
    cheers
     
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