# Possible to MIG weld a 4130 frame?



## henryl (Feb 6, 2004)

Is it possible to MIG weld a frame out of 4130? Would heat treating be required? The welds don't need to look pretty, I just want them strong. I am contemplating a custom frame (somewhat bicycle related but not a bike frame) and MIG talent is much easier to find. Any info appreciated.


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## RoyDean (Jul 2, 2007)

Yes. Maybe a little (or a lot) difficult to control, but certainly possible.

Heat treating depends on who you ask. I think everyone would agree that normalizing the entire completed frame couldn't hurt, but people will dissagree on whether or not it is necessary to do so on thin wall tubing....


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## Walt (Jan 23, 2004)

*Yes, no.*

It can be done, and you do not need to heat treat afterwards. If you are looking for *someone else* to build you a bike frame, you will not find anyone who works with MIG who can do a decent job, though. MIG guys are not bike guys, and vice versa.

-Walt



henryl said:


> Is it possible to MIG weld a frame out of 4130? Would heat treating be required? The welds don't need to look pretty, I just want them strong. I am contemplating a custom frame (somewhat bicycle related but not a bike frame) and MIG talent is much easier to find. Any info appreciated.


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## MichauxYeti (Nov 10, 2005)

MIG doesn't work well on the relatively small diameter tubes that are found on bicycle frames. The puddle simply needs to move too fast for 99% of the welders out there to control as they keep their gun angle rotating around the tight radii. Another issue is that a MIG process typically has too high of a heat input for the thin wall tubes. As an example, a weld procedure here at work for MIG welding .050-.125" mild steel lists 80-120 amps and 15-19 volts. A general rule of thumb for TIG welding is 1 amp for each thousandths of material thickness.


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## henryl (Feb 6, 2004)

So would you consider .05-.06" thk 1-1.25" dia tubing too thin for MIG? What I am working on wouldn't use the paper thin tubing of a typical bike.


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## MichauxYeti (Nov 10, 2005)

Then maybe you'd get a better answer from a bunch of guys who aren't bike geeks.

What diameter of tubing are you working with? FWIW, race car builders MIG weld 2" 4130 tubes all the time. They're probably working with .125 or thicker tubes though.


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## peanutbutter (Feb 18, 2005)

mig works for freak bikes and such, but doesn't look good, and has carries a very high risk of blowing through the tube. the reason it works ok for freak bikes is that quite often the goal is completing a bike that rides and works, without necessarily looking good or handling well. if handling and aesthetics aren't your thing, go for it!


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## RoyDean (Jul 2, 2007)

henryl said:


> So would you consider .05-.06" thk 1-1.25" dia tubing too thin for MIG? What I am working on wouldn't use the paper thin tubing of a typical bike.


Somebody with MIG skills should have no problems with .065".... but I don't know about anything less than that.


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