(MBBO#05 Class 2) Flashback GT - Done!

Discussion in 'MBBO 2016 BIKES' started by tjwilson, Sep 7, 2016.

  1. tjwilson

    tjwilson Pro Member

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    I got lucky with both the chance to see it and with the shot for sure. It was even more incredible in person.
     
  2. tjwilson

    tjwilson Pro Member

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    I'm glad too! I already feel so far behind.
     
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  3. tjwilson

    tjwilson Pro Member

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    A weekend spent whittling metal and trying to coax tight fitments between tubes. Doesn't look like a whole lot of progress. Baby steps, but all steps are going forward so far. Also picked up a seat and a couple hi-rise handlebars at a local swap meet. The seat upper and lower pans will provide a good start for the final seat. As for the bars, I had been thinking of modifying a set of drop bars to hi-rise. The ones I found will provide a good back-up if I run out of time plus, the price was right.

    headtube06.jpg

    headtube07.jpg

    headtube08.jpg

    fitment01.jpg

    fitment02.jpg

    fitment03.jpg
    fitment04.jpg
     
  4. pholTmonx

    pholTmonx

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    Killer fitment. You have patience for sure... i tend to cheat short taper grafts just to avoid the amount of time... but the outcome is worth it.. very cool.
    *edit... get it finished with a tig and leave the welds... no reason hide that kind of work! Itll lool slick regaurdless and gives other fabricators something to stop and drop jaw at ;)
     
  5. LukeTheJoker

    LukeTheJoker Moderator

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    Going well!
    Every time I see this frame I think of a Kangaroo...

    Luke.
     
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  6. tjwilson

    tjwilson Pro Member

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    Thanks! I know there's going to be a lot of stress in that area. Figure if I have a tight fit I'll increase the odds of getting at least a couple areas with strong welds. I'd love to get into TIG. There's even a maker space nearby that I've used in the past for powder coating. Like a club membership with training and every kind of metal working machinery imaginable. Some day.
     
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  7. tjwilson

    tjwilson Pro Member

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    Especially that last image, absolutely!

    Hmmmmm :39: ... with the right patina, a kangaroo rat?
     
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  8. LukeTheJoker

    LukeTheJoker Moderator

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  9. tjwilson

    tjwilson Pro Member

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    A little more progress on the frame backbone. A few molten metal caulk gun (MIG) weld close ups. Should probably spend some of my fitment time doing a few more practice welds.

    weld01.jpg

    weld02.jpg

    weld03.jpg

    Overview of the jig setup I'm using. Managed to keep things surprisingly straight.

    frankenjig.jpg

    Initial clean-up of the welds. Didn't want to spend too much time till I prove out some of my design assumptions. Need to make sure everything will actually be strong enough before making it look pretty.

    weldcleanup01.jpg

    weldcleanup02.jpg

    weldcleanup03.jpg

    Bottom bracket prep and fit.

    bb01.jpg

    bb02.jpg

    MTB rear that will be donating pieces for the chain/side/seat stays.

    reartubing.jpg

    The ambitious plans for the weekend are to end up with a rolling frame!
     
  10. OddJob

    OddJob

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    I like your jig set up. Looks like you have some nice curvy tubing for your rear 'triangle'....although using the word 'angle' on your build is a stretch! :bigsmile: Everything flows nicely!
     
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  11. tjwilson

    tjwilson Pro Member

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    Thanks. For the price of a few pieces of 1x1 tubing and some clamps the jig seems to be working well. The proof will be once it's standing on it's own with the wheels.
     
  12. tjwilson

    tjwilson Pro Member

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    Things didn't go quite as quickly as hoped this weekend. Got about a third done of what I planned. Not a real surprise, pretty much typical. Here's some detailed documentation of minor progress ;)

    Rear triangle chop and straighten. Needed to reduce the distance between chainstay sides by about an inch. Dimpled the sides a little in the process but those will be easy to fill later. Top left is before, top right after, bottom in process.

    chainstayBend.jpg

    Template for dropouts

    dropoutTemplate.jpg

    Dropouts

    dropouts.jpg

    Positioned in jig

    droptoutPositioned.jpg

    Chainstay to BB connection

    chainstayBB01.jpg

    chainstayBB02.jpg

    chainstay.jpg

    Fitment still needs a little finessing. I'll probably add a small gusset to each side to help strengthen it up.
     
  13. LukeTheJoker

    LukeTheJoker Moderator

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    Looking good!

    Luke.
     
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  14. tjwilson

    tjwilson Pro Member

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    Had the chance to get some work in yesterday. Still need to fabricate the side / seat stays but, here it is to date.

    Bottom bracket and dropout welds.

    weld01BB.jpg

    weld02Dropout.jpg

    Frame pulled from the fixture.

    frameInProcess.jpg

    With wheels and checking for straightness.

    sideRearview.jpg

    A couple shots with handlebars.

    threeQTRviews.jpg
     
  15. tjwilson

    tjwilson Pro Member

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    The chain stays required a little massaging for sprocket and crank clearance.

    Sprocket interference.

    sprocketInterference01.jpg

    Added a dimple with a small section of half inch tube and a hammer while the chain stays were clamped and backed.

    sprocketInterference02.jpg

    Left crank interference.

    leftPedalInterference01.jpg

    Flattening chain stay with clamp and piece of 2x4.

    leftPedalInterference02.jpg

    leftPedalInterference03.jpg

    Overview of clearances. Should be okay if I don't use too many layers of paint!

    clearanceOverview.jpg

    Side view with crank, sprocket and chain.

    sideviewDrivetrain.jpg
     
  16. LukeTheJoker

    LukeTheJoker Moderator

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    Looks awesome, but the strength of it worries me, I know there is added tubes to run yet though!

    Luke.
     
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  17. tjwilson

    tjwilson Pro Member

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    Thanks! I'll bet you're not as worried as I am about the strength ;). The tight clearances to the crank and sprocket ought to act as a good gauge to any deformation!
     
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  18. OneHorsePower

    OneHorsePower

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    Aww man i forgot to check the watch botton , i missed a bunch :doh:
    Looking great! :rockout:
     
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  19. pholTmonx

    pholTmonx

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    It really gorgeous... I do think it'll triangulate well with the seat pan and other bars.. a few gussets and it'll displace effectively..
    I'd be more interested in how the stays deal with all those dimples.. from my understanding of the draft, it seems like there would be a great deal of torque going on down there at all times, I don't have experience with how they would perform because the wall structure in my mind is "compromised". I'm no used to building at this scale..
    On a Harley that would be a fatigue point so it's a no no..
    But it's a bike and not vibrating itself to death constantly also :bigsmile:..
    Regardless I'm in awe:)... It's a beauty
     
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  20. Chad T

    Chad T

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    Wow...another great scratch builder in the mix...really turning out awesome.
     
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