Twin Cylinder Build

Discussion in 'A Work In Progress' started by Johno1958, Apr 25, 2018.

  1. Apr 25, 2018 #1

    Johno1958

    Johno1958

    Johno1958

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    Hi all.
    Just started building a twin cylinder sort of loosely designed on Longboy's engines, although already I can tell mine is going to be ugly. It's going to be as simple as I can make it and hopefully it will run.I have bought a slitting saw and boring head for the mill neither of which I have used before so I will learn something maybe. The crankshaft is bolted together through a thin section bearing 17x26x5mm with four m3 bolts ....make that three just broke a tap off in the last hole :wall:not going to get that puppy out but three will hold even two would I think.Just a little rubbing so I have taken a whisker of the back of the webs . Hoping I won't have to use a large flywheel as these webs are thick and heavy 1020 steel .
    Cheers
    John

    IMG_20180423_145827919_LL.jpg

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  2. Apr 26, 2018 #2

    Herbiev

    Herbiev

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    I'll be following along. Use plenty of lube on the slitting saw. :)
     
  3. Apr 26, 2018 #3

    Longboy

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    Looks like you can re- drill four new holes and tap in that same piece.....you have "experience" now!:thumbup:
     
  4. Apr 26, 2018 #4

    Johno1958

    Johno1958

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    You know, I never thought of that :rolleyes: thanks.
    John
     
  5. May 5, 2018 #5

    Johno1958

    Johno1958

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    Got the crankshaft nearly there. A little more machining on the rear shaft to be done . It runs quite freely a little drag due to five sealed bearings.There is two in each end one in the center. The conrods will each get two 8x12x3.5 mm thin section bearings in the big end and a couple of 3mm for the wrist pins.
    It's probably going to be a long build because working night shift gives me the "Brain Fuzzies"and a lot of the time I can't be bothered.
    Cheers
    John

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  6. May 6, 2018 #6

    Cogsy

    Cogsy

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    How did you get a sealed bearing in the centre?
     
  7. May 6, 2018 #7

    pp2076

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    Isn't that where the bolted bit is? ie insert bearing, bolt together...
     
  8. May 7, 2018 #8

    Johno1958

    Johno1958

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    Yes the first picture says it all.
    I remade those two center webs after breaking the tap . Before they were a sliding fit now a light press fit . I saw this way on another forum a while back and can't for the life of me find it again but these bearings are 17mm id and 26 od and 5mm wide after using them I would have gone larger maybe 20 x 35 x 5mm
    which would make thing a whole lot easier but they start to get pricey .

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  9. May 7, 2018 #9

    Johno1958

    Johno1958

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    These 6804ZZ 20x32x7 Shielded Bearing would be a lot better at $ 10 or a 10 pack if you plan on using more at $47.
    Cheers
    John
     
  10. May 7, 2018 #10

    Cogsy

    Cogsy

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    Ahh, I see now. I thought it was a solid crank (confused with another build I think). I should have re-read...
     
  11. May 13, 2018 #11

    Johno1958

    Johno1958

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    Started on the cylinder and head.The cylinder lining is some hydraulic tube already honed .I have about 900mm of it .Bore and stroke is 25 x 34 mm.
    First time I have ever used a boring head on the mill. Liked it but I have to work on getting a better finish.
    John

    IMG_20180513_132101978_LL.jpg
     
  12. May 13, 2018 #12

    Cogsy

    Cogsy

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    Looking good, though I see what you mean about the bores being a little rough. Maybe try a few lighter cuts at very slow down feed toward the end of the boring job.
     
  13. May 13, 2018 #13

    Longboy

    Longboy

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    The tool bit has to be 90 degrees to the wall of the hole you create. A lead or lag on the angle gives choppy, galling results per my first time making bores too! :eek:
     
  14. May 14, 2018 #14

    Johno1958

    Johno1958

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    Thanks Cogsy and Longboy.
    Luckily enough I have a little bit of meat left on the hydraulic tube that can take a clean up cut.
    John




    Lot better

    IMG_20180514_111636639[1].jpg
     
    Last edited: May 14, 2018

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