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Thread: My second bike

  1. #1
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    My second bike

    I've noticed a couple posts about getting into frame building. I responded to one but thought I'd start a new thread showing what you can do with one frame under your belt and a pretty minimal setup. I'll also briefly explain my process and what I've learned building the two bikes. Please keep in mind, I'm still a newbie... by no means do I claim to be an authority on anything, but I thought my experiences to date might be interesting to some who might be where I was before I started.

    Tools and supplies I've bought:
    MAPP gas and torch from Home Depot - ~$35
    assorted files - $15
    digital angle finder from sears - $27
    1 tube set, lugs, silver, flux, dropouts from Henry James - $300
    tube miter from Grizzly - $50 (although I would recommend splurging on the Ol' Joint Jigger)
    bench grinder from Grizzly - $70
    Rigid hole saw kit for the tube notcher - $40

    Otherwise, I had some other basic hand tools already.
    Hack saw
    Vice
    Dremel
    work bench
    degreaser
    cutting oil

    Brief explanation of process steps:
    1. I start off with geometry. I used to do real engineering work and was ok with Autocad. Nowadays, I just pretend to be an engineer and can't really justify having Autocad on my computer, so I use Cadintosh... It's free for the Mac.



    2. About the same time, I start thinking about tubing and lugs. I've used both Nova and Henry James for tubing, lugs, and the other parts you need. Both of their web sites suck frankly, but I would recommend reading Henry James' price list and tech info PDF docs. While you're at it, check out the last page of the tech info doc and pick one of the "suggested" tube sets if you don't really know where to start.

    3. After I get the plan and the parts together, I start cutting metal.
    A. I miter the bottom of the seat tube and braze it to the Bottom bracket lug. No jig required really. You want to make sure you braze it in reasonably straight, but there won't be a lot of slack anyway.
    B. Miter the top of the down tube and braze to the head tube. Again, no real jig required here, but you want to make sure the angle is correct since the lugs do have a degree or two of slop.
    C. Cut and miter the down tube and braze assembly A to assembly B. This one is a little more complicated. You need to make sure the angle is right but also need to make sure the four "members" are in the same plane. I do this by making sure all pieces are horizontal with my digital angle finder before brazing.
    D. Cut and miter the top tube and braze to assembly C. No jig required. But you will want to make sure your angles are good since you can easily muscle the lugs out of where they are supposed to be.
    E. Cut and miter chain stays (only cut the drop out end) and tack into place in the bottom bracket with a little silver. This part is the biggest pain in the butt in terms of alignment. Without a jig, it's kinda difficult to make sure everything is good before brazing. Thus, the tack instead of the full braze.
    F. Cold work (bend) the chain stays into place if they are not after tacking.
    G. Braze on the dropouts to the chain stays. I use a dummy axel to keep them in place. (recheck alignment)
    H. Cut the seat stays to size and make your seat stay caps or braze on your purchased seat stay caps.
    I. Braze the seat stays to the dropouts. (recheck alignment)
    J. Braze the seats stays to the seat tube/top tube lug.
    K. Braze on your purchased (or fabricated) seat stay and chain stay braces.
    L. Cut off any excess head tube.
    4. Take completed frame to your local shop for head tube facing/reaming, headset installation, and BB facing/reaming

    My first bike:

    More pics here:
    http://www.flickr.com/photos/jasonwa...7609554950363/

    My second bike:

    More pics here:
    http://www.flickr.com/photos/jasonwa...7612578202202/

    What I've learned:
    1. Brazing is definitely an art. That said, use lots of flux, try not to get too happy with the silver, and use gravity to your advantage. My first brazes were weak but I'm confident all my brazed on the second bike are super strong. Maybe not all of them are pretty (see above on too happy with silver) but I know I got good penetration and bonding. Even the brazes on my first bike aren't bad though after I redid some of them. It's still a new bike, relatively speaking, but after a few hundred miles, all the joints still look/feel good. (I clearcoated the frame so I could inspect it easily.)

    2. Think first, then think again, then cut. (Also valid if you replace "think" with "measure.")This is applicable almost anytime you touch a cutting tool. I avoided more than a few costly mistakes by catching an error before it was too late.

    3. Watch the videos online about brazing. Read the websites online about techniques, design ideas, and processes. Use the forums for help with questions. I learned a ton this way!

    I think that covers the bulk of it. Thanks for reading!

  2. #2
    tuz
    tuz is offline
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    Thanks for sharing it looks great! Are going to leave the extended seat tube? And something looks weird on the head tube, but I guess you'll have it faced and reamed.
    homebuilt commuter, mixte, road and track (+ Ryffranck road)
    bla bla blog

  3. #3
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    Yes, the seat tube was profiled to match the lug. If you dig into the album link, you can see more detail.

    And yes, the head tube needs to be faced and reamed. I leave a mm or so of material to account for that and also to make it easier to see the silver flow through to that side of the lug.

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