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Thread: Fat Tire Bike

  1. #11
    Moderator DavidF's Avatar
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    Once again in my laziness...... "Electric motor!!"
    And you need to mow your grass... Wow, thats grass too...I only have weeds to mow down
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

  2. #12
    Senior Member Robert's Avatar
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    I am seriously considering an electric motor. Have you seen this?

    https://geoo.com/products/geoorbital...-44BoCFKbw_wcB

    R
    Last edited by Robert; 06-11-2017 at 02:40 AM.
    "Whether you think that you can, or that you can't, you are usually right."
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  3. #13
    Moderator DavidF's Avatar
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    Quote Originally Posted by Robert View Post
    I am seriously considering an electric motor. Have you seen this?

    https://geoo.com/products/geoorbital...-44BoCFKbw_wcB

    R
    No, thats new to me. Very futuristic. I was thinking more like this...
    http://youtu.be/9rIIJbDkpN8
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

  4. #14
    Senior Member Robert's Avatar
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    R

    - - - Updated - - -

    Rear dropout:


    Dropouts welded in:


    R
    "Whether you think that you can, or that you can't, you are usually right."
    - Henry Ford (1863-1947)

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  5. #15
    Senior Member Robert's Avatar
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    OA brazing is much easier than TIG on these thin walled tubing joints.





    Next is the bottom bracket. It needed extensions to for the crankset to clear the chainstays. Thick tubing was machined to fit the bearings and then TIGed :



    The crank spindle needs to be about 14" long. I cut a standard spindle in half and embedded each end in a shaft that fit through the crank bearings:


    That is TIG brazed.

    Robert




    R
    "Whether you think that you can, or that you can't, you are usually right."
    - Henry Ford (1863-1947)

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  6. #16
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    That is some nice fab work.

  7. #17
    Senior Member Robert's Avatar
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    Thank you!

    Next on to the extra long crank spindle. Here is the spindle end cut from a Shimano Dura Ace:



    Here is the TIG brazed piece. One end is as brazed and the other after cleaning up on the lathe:



    So the TIG brazing was a total failure!!! I put some modest load on the spindle and...failure.



    So.... I machined off all the braze material and carefully TIG welded the spindle ends in place.



    The shaft is 20mm and setup so I can use standard angular contact bearings for the crank.

    I think the TIG brazing is a bad idea in general because you can't help but melt some of the base metal. Then you get a weird alloy of steel and bronze that probably has some brittle areas promoting failure. I will stick to OA brazing and TIG welding going forward.

    Robert
    "Whether you think that you can, or that you can't, you are usually right."
    - Henry Ford (1863-1947)

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  8. #18
    Moderator DavidF's Avatar
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    When I used to fix propeller shafts I would drill and tap both pieces, then put a threaded stud in and screw the two parts together and finish up by tig welding the outside that was chamfered back to the stud. Never had one fail. Just food for thought...
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

  9. #19
    Senior Member Robert's Avatar
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    Thanks David: Note that the spindle ends are hardened and cannot be threaded. The grinding was done with a diamond wheel.

    Ready for the road!





    Rides great!

    https://youtu.be/DbcvbpZ4OFs

    R
    Last edited by Robert; 06-21-2017 at 04:21 PM.
    "Whether you think that you can, or that you can't, you are usually right."
    - Henry Ford (1863-1947)

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  10. #20
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    Okay you were right. That I cool. Will you do brakes?
    Mark

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