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Thread: MIG on a bike?

  1. #1
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    MIG on a bike?

    hi all,
    I'm new to the forum, though i've been riding all my life.
    i do a bit of mig welding, and have done some arc, but never any tig.
    i would like to start building bike frames in the near future, and was wondering if it would be possible to use a mig welder to build a frame. the one i have access to is one of the smaller ones.

    if not, i was wondering if any tig welder would work, because from what i've seen, they range in price from several hundred dollars, which i might be able to manage, to multiple thousands, which i definitely can't afford...

    any input would be welcome and appreciated, thank you
    Be Hip, Be Square
    Squarewheel Bicycles

  2. #2
    Senior Member Nessism's Avatar
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    I know a builder that MIG'd together frames all the time. The welds were not as aesthetically pleasing as TIG, but the frames held together just fine.
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

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    Cheaper MIG often refers to small AC machines that use fluxed wire. As with any welding tech there are reasons for it, but they would be an awful choice for bikes. No MIG is ideal, see the recent thread I started on MIG welders and bike frames. The cheapest welding option is gas welding. Particularly for the many who have a cutting torch rig already since the torch is under 100. Gas could be the best welding option structurally, one certainly has nothing to worry about.

    If one goes to a TIG machine, it is possible to do frames with a cheaper unit (1500-2000, vs. 3000-6000), though certainly not to the highest commercial standards. TIG is one tool purchase where cheaping it out is enormously more expensive over the long run. TIG is great because of the control, and everything that ads to the feature set costs big money. To get anything decent at all will cost half big money, not paying the extra tranche then when you are already invested, is generally a big mistake. It is a mistake for a pro because he needs all the bells and whistles, and it is a mistake for most amateurs because they normally have wider horizons than pros. In the home shop the ability to weld aluminum, for instance can save or make you money fast, so a limited box can be a bad investment. The only person who should consider a limited box is someone who isn't a pro, and knows they could never be interested in full spectrum welding. Even then there are safety and ease of learning things that favour the more expensive sets.

    - There are sets in the 300 dollar range. Remember you have to rent gas. Often the cheap set with regulators, gas, torch and pedal will be within a few hundred of a mid-range kit. It is likely to require amazing welding chops to use a rock bottom set well.

    - The conventional TIG units weight a lot more, and require more input amps, but they can be quite good as processing the current in useful ways. Basic TIG really needs:

    HF start, pedal or finger control, square wave and ac/dc are an advantage, but not necesarry for chromo.

    - Inverters are the best option these days but still expensive.

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    Thank you both for the input.
    It sounds like MIG will work, but is definitely not the best option, especially with the little guy that i have.
    I was looking at some new miller TIGs, and i found one that was about 2000, which i could probably manage, the next highest being somewhere around the 5000 range, which i probably cant do.

    So I'm starting to look into craigslist/ebay, and i found some that are pretty reasonably priced, but most of them are advertised as stick, tig, plasma cutter combos. So i was a little suspicious; if it has all of that why would it be so cheap? ( found a bunch for sub 1000) I suppose it could just be that they are used, but i've never heard of these combo things before, so i wasn't sure. granted, i know relatively little about the world of welding equipment, so maybe it's just that. Do you know of the combo welders? Are they any good? also, i was wondering; what voltage/amperage should i be looking for?
    About gas welding, i dont have the torch rig, although i would love an excuse to get one. do the welds come out nice? i've never done any torch welding, i'm not really very familiar with it.
    and i am mostly interested in doing chromo, although i could definitely see myself branching out as i get a little (or a lot) more experience.

    thank you again for all of your help.
    Be Hip, Be Square
    Squarewheel Bicycles

  5. #5
    Senior Member Nessism's Avatar
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    Torch welding is very uncommon on bicycles; guys with torches braze their joints when building bikes. Gas brazing is the most popular method for homebuilders since the equipment is pretty cheap. You should be able to get a complete setup with tanks for about $400 or less.
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

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    Oh, cool, very good to know, thanks
    i'll look into that as well. it would be pretty nice to have a torch anyways
    Be Hip, Be Square
    Squarewheel Bicycles

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    Nessism is right on. It's true that torch welding is uncomon, though there are a few builders doing it. The main problem is that the results aren't like the pulsed machines that seem to rule these days. The EAA teaches seminars on aircraft welding and some of those instructors say gas welding is more forgiving in average hands, and they can usually turn out a gas welder more quickly than a TIG welder (that said TIG is coming on in the aircraft field as more amateurs get the sets), and that does not include the TIG aesthetics we see on bikes, an even higher level. Planes are all about the structural weld.

    Gas torch welding has advantages over brazing in the small shop it doesn't require any flux and those eye opening MSDA sheets. Faster too, which is safer in the amateur shop. Funny I saw this economics pieces about Japanese auto makers in the US. Picture of the Toyota line. They were torch welding the joint between the rear pillar and the roof, one guy on either side with an aircraft torch, Didn't expect to see that. Things that make you go Hmmm.

    I think most of the joinery practices in bike making are pretty antiquated, except for the TIG guys. Makes sense to do as the leading makers do if you are commercial, but a lot of times there are better/other ways if you just make for yourself. A lot of the ideas floating around come from the marketing wars when they were trying to stave off cheaper welded frames. It's like the Apple Vista ads with the bike biz played by the Vista guy.

  8. #8
    Senior Member Nessism's Avatar
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    Auto bodies are spot welded together. Those guys on the assembly line with torches were most likely filling joints with body filler (similar to lead, but not lead). I've also seen some brazed joints on cars, but never gas welds.
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

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    I would certainly defer to you, but it looked like gas welding, and not lead work, though I have only seen the latter on Monster Garage. What you say makes more sense.

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