Welding on Big box store bikes?

Discussion in 'Motorized Bicycle Welding, Fabrication and Paintin' started by Birddog1148, May 13, 2010.

  1. sojudave

    sojudave New Member

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    You bike is already welded. That dude might not be to smart. I have tried to mig weld a bike frame, but I burned through it. I am not a good welder yet either. I took it to a guy I know and he smoothed out some of my mess with a mig, no problems. I'm sure it depends on the frame. If the metal sparks when you hit it with a grinder, then it is steel-ish. If it simply turns to dust, it's probably aluminum.
     
  2. Birddog1148

    Birddog1148 New Member

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    Or use a magnet, besides ferrous welds wont stick to alluminum Thats how I get broken steel studs out alluminum heads, I just put a nut over the broken stud and weld it on, weld only sticks to steel
     
  3. nidyanazo

    nidyanazo New Member

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    Been there, done that. lolz
    Had to rebuild a little patch that burned through, but my bike is holding up great.
     
  4. BlueBloodCycles

    BlueBloodCycles New Member

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    If your blowing holes your using to much heat! dial it down and your feed. If you use to low of heat though, it heats up the surrounding base metal alot more than short concentrated welds. I also wouldnt use flux when welding so no smaw. But mig and definatly tig will be just fine.

    I think the guy at the bike store was trying to sell ya something, or he was thinking about aluminum. Some aluminum alloys are heat treated, and you want to preheat those before you weld them and postheat after. Others are not and do not require it.

    Heat treatable series: 2000, 6000, 7000.
    Non-heat treatable: 1000, 3000, 4000, 5000.
     
  5. motorbiker

    motorbiker New Member

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    I am hearing cheap, thin, not heat treated steel.

    Maybe not the best choice for a disk brake mount.

    Welding the cheap, thin, not heat treated tubing will not make it stronger and there could be huge stress on the welded mount depending on how hard you hit the brake.

    I would change out that fork with a nice one set up for a disk brake.
     
    #25 motorbiker, Jul 14, 2010
    Last edited: Jul 14, 2010
  6. kicking

    kicking New Member

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  7. caduceus

    caduceus New Member

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    All that clip does is hold the drum brake in position so it doesn't rotate. If you were to put the load of a caliper on that thin piece of metal the twisting reaction would distort it immediately.

    That machined adapter looks like it might do the job though. I'm thinking of replacing the band brake with a disk and that looks like the way to go.
     
  8. kicking

    kicking New Member

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    xct2
    let us know how it gos with the machined adapter . and give some links if you can , and pictures if you have time ' ; Latter still kicking
     
  9. moronic_kaos

    moronic_kaos New Member

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    To the OP..

    Just welded a couple brackets for a different gas tank today. I found the bike (Cranbrook) easier to weld then the sheet metal I used.

    Beat on them with a hammer a few times before I hooked everything up (nobody likes a flying gas tank), and it holds perfectly fine. And I'm what you would call a below amateur welder.
     
  10. 42blue15

    42blue15 New Member

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    Welding on an aluminum frame or fork is probably a bad idea, as the welding heat softens the aluminum permanently (unless you have it heat-treated again, that is).

    Welding on steel is possible, but bronze-brazing it would be safer.
    Thin steel will tend to carburize a lot on the back side and flake off, weakening the metal around the weld. Brazing is done at a much lower temperature, and totally avoids this problem.

    This is not a good idea.
    Normally the caliper on the front side gets pulled forward, and the wheel axle gets pushed UP into the dropouts.

    If you mount the caliper on the rear of the fork blade, then the caliper gets pushed into the fork blade (no problem there) but the caliper's stopping power pulls DOWN on the axle. A few people who tried this have had their front wheels come out while riding because of this when they stopped hard. The couple times I saw pics, the dropout itself cracked in half.

    Motorcycles can do this (mount the front calipers behind the fork blades) because they do not have slots in their fork ends--they have holes, and a thru-bolt.
    ~
     
  11. civlized

    civlized New Member

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    Makes you wonder why they are factory built this way.
     
  12. 42blue15

    42blue15 New Member

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    The ones that come that way have dropouts built stout enough to take it.
    If you research the issue online, you will find several examples of dropouts that cracked apart.
    ~
     
  13. Maxvision

    Maxvision New Member

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    If you have oxy-acetelyne to weld with try the silver brazing rods with the blue flux on them. You can buy them at Home Depot or most any hardware store. Brazing makes it easier to get a nice fillet to your weld and the silver rods are MONDO hard, VERY high tensile strength. Also, you'll never get the temp hot enough to burn through whatever you're brazing to. I use them all the time and have yet to have anything break off.
     
  14. frostythesnowman

    frostythesnowman New Member

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    Any experiences welding on the hubcenters of the rear wheel on big-box stroe bikes? Building a full-custom MB, and I have to weld a new sprocket and spacer onto the rear wheel. Any input would help.
     

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