# Going to MIG weld a steel frame...



## The_Boy (Sep 15, 2005)

... what size wire is best? 100% argon or argon/CO mix? MIG, its what I've got and what I know, so its what I am doing.


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## TacoMan (Apr 18, 2007)

I would get some 1/16" wire, then use a TIG welder.


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## The_Boy (Sep 15, 2005)

I appreciate your quick response, but:



The_Boy said:


> MIG, its what I've got and what I know, so its what I am doing.


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## pvd (Jan 4, 2006)

Wouldn't it be better to just flush $180 in materials down the toilet?

Sounds like you need to learn a new skill.


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## Rich N (Dec 2, 2004)

*You Asked...*

although I wouldn't do this way. Here are your answers.

3/32" Wire. Argon (75%), CO2 (25%) Mix. Tig is 100% Argon.

Watch your heat. Watch your wire speed. You want no spatter / snots / boogers....

Good luck. Post some pictures.


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## gabe (Mar 25, 2004)

*Wouldn't it be better to just flush $180 in materials down the toilet?*

Harsh but true...................and if you somehow pull it off, well never mind.


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## The_Boy (Sep 15, 2005)

RichN, thank you for a productive answer. 

PVD, give me your TIG and I will gladly learn a new skill. Obviously if I had my druthers MIG welding wouldn't be my first choice. But since I have a MIG and it is possible to weld a bicycle frame together with one, I thought I would give it a shot. Plus, its not like this frame is going to be the crown jewel of my bike collection. Really though, you keep up your extreme mentality, hope that works out for you.


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## Dan0930 (Oct 25, 2005)

You got 4 honest helpful responses but you still insist on driving in a screw with a hammer...


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## Evil4bc (Apr 13, 2004)

Um yea tig gonna be your best bet for steel.
MIG can be used on frames , I've seen it done but not very effectivly .

The heat from the MIG is gonna blow huge holes in your bike frame , I really dont see this working very well.

I might suggest calling your local AIR-GAS company and renting a Miller Dynasty 200DX for a month and welding up your bike .


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## rodar y rodar (Jul 21, 2006)

The_Boy said:


> Obviously if I had my druthers MIG welding wouldn't be my first choice. But since I have a MIG and it is possible to weld a bicycle frame together with one, I thought I would give it a shot.


Makes sense to me. Good luck with it.


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## pvd (Jan 4, 2006)

how's this:

i tried to mig a frame once. the results were so totally junk that it went from the jig to the dustbin. you will probably do worse.

oxy\ace is common. you can gas weld a frame or fillet braze one.

i promise that your frame will be totally unusable when you are done. junk. total crap.

time to learn a new skill. the wrong tool is the wrong tool.


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## The_Boy (Sep 15, 2005)

Honestly, that was a much better answer. Thank you.


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## NEPMTBA (Apr 7, 2007)

Grab an Oxy set up and Braze it. It will look better and you will be happier in the end. Mig just doesn't have the control options. It's great for making a Trailer or a Rack for holding something, but not for precision!


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## bdierks (Jul 23, 2007)

I just cant see how a mig welder would not work. Some say " you will just burn big holes through the tubes because of the heat" Well Sr. you must have now idea how to weld. I weld really thin sheet metal all the time with my mig welder. Body shops all around the world use mig welders. Sure mabey its not the best way to do it, But it can most certanly be done. I say go for it. take your time and make sure all your connections fit really good and are really clean. Theres more than one way to skin a cat...


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## DeeEight (Jan 13, 2004)

If MIG is good enough to assemble aircraft and racing cars, its good enough to do a bicycle frame. Not The_Boy's fault the rest of you can't weld with one very well.


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## mtnbiker4life (Sep 19, 2005)

MIG welding thin walled tubing is an art. It's not the best process for the application at hand. MIG best lends itself to thicker walled metals. Not to mention the geometry of welding small tubes together......I would TIG or Braze the tubes. MIG is an easy process to learn but it still has to be perfected to be able to achieve a good weld. I'm not a certified weld but have taken enough welding classes to know this is the wrong process for the application.


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## Blowout (Dec 31, 2003)

*MIG is possible, but...*

I have welded a few bikes with MIG, but they were more hack and chop jobs rather than MTBs
Here is a cargo bike:








A chopper:









As people have mentioned, blowing through thin tubing is the biggest danger. If I were to weld a bike up from scratch with a MIG, I would try to use straight gauge 4130 at least .049 or thicker. This will lead to some weight issues if you were aiming for a lighter frame. 
I am working on fillet brazing with an oxy/propane setup for my next bike, a dedicated cargo bike built from raw tubes instead of discarded kiddie bikes. I would love to have a TIG set up and learn to use it as well, but economics does not allow for that right now. If you have the tools, use them. If you are a good MIG weldor, then you can make a good frame. If you want to learn another process, look at the local community and technical colleges as many offer Saturday or evening welding classes that would allow you to bring a project and work on it with their machines.
Good luck, and please post pictures of the build.


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## Ultra Magnus (Jan 13, 2004)

Doesn't SWD bikes mig weld their frames?
https://www.swdracing.com/images/Pivot.jpg

Looks mig welded to me. though a DH bike is a far cry from an XC bike...

BTW, I'd use like .030" wire, or thinner maybe, but you can have trouble feeding too thin wire through too long of a mig gun lead. You have to know your equipment.

BM


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## MendonCycleSmith (Feb 10, 2005)

While I'd agree with the TIG majority completely, it's the best way to get the job done, it's certainly do-able with a MIG. Aren't most Walmart bikes held together that way? That said, they hold up to an average beating, and if you want to break a frame out on the trail 'cause you went beyond normal use, it's all in good fun anyway, right? :thumbsup:


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## DeeEight (Jan 13, 2004)

In the past 20 years, MOST of the failed frames I've seen where the break/crack developed at a weld, they've been on mid/high end TIG'ed bikes, or brazed bikes, but not on cheap MIG-welded bikes. This year alone I've seen several Rocky Mountains (TIG welded) and Oryx/Mieles (brazed).


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## popoff (Dec 4, 2007)

if you really want to build and you know mig (hopefully very well), you might as well go for it. the note about heavier wall thickness is a good point, maybe straight gage as it's cheaper to make mistakes on. you should be able to get .023" wire pretty easily and be sure to buy a good brand, not department store or harbor freight stuff. look into using pure argon to reduce the heat input (pure argon transfer's the least amount of heat to the workpiece, c25 is hotter, and pure co2 is the hottest and spatters the most).

make sure your joints are super tight before welding, and tip the torch toward the thicker side of the joint to focus the heat more there. make some practice joints first. do a few tacks, then weld each joint in segments to reduce warpage ( work your way around like tightening lug nuts). if you can find tubing that fits tightly inside the main tubing you can make backer tubes to let you use thinner wall tubing. this was common practice before butted tubing, but those were brazed frames. 

i think people would be surprised at how many modern bikes and other welded structures are mig welded. granted, the manufacturers use super high end machines with electrical profiles to build the weld, but a bike frame is very possible. it will likely be a tank, but you built it. 

Mike


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## WadePatton (May 10, 1999)

*get some scrap 4130*

and do some practice joints--fully mitered. THAT will tell you more about _your_ MIG prowess than any comments here. If you can join .035 inch tubing without issue, then you might even try real bike .9/.6/.9mm butted tubing.

Going to take the exact same amount of time doing miters and fitment. May as well give it a whirl. If you aren't satisfied with the result, you can start over with o/a or TIG.

Let us know how it comes out.


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## DeeEight (Jan 13, 2004)

Ummmm 0.035" is .889mm so .9mm would actually be thicker still and thus no trouble at all if he can do the 0.035". The center butted section makes no difference what thickness it is, the welding isn't going there !


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## Walt (Jan 23, 2004)

*What?*

Nobody is going to notice .011mm worth of wall thickness when welding. It's certainly not the case that welding .889mm would be hard, whereas .9mm would be "no trouble at all". They are so close that it's exactly the same amount of trouble. Trust me on this.

FWIW, ".035" and ".9mm" are terms that are used interchangeably when talking about bike tubing. Bike stuff is sold in metric units, aircraft type straightgauge 4130 is sold in imperial. Honestly, I'm pretty sure the tube manufacturers can't produce anything close to a .011mm tolerance anyway, so it's really just academic.

Dirtzilla's point, I believe, was that practicing on scrap the same thickness as the butts on "real bike butted tubing" is a cheap way to see if you can weld the tubing without ruining a bunch of (more expensive) butted tubes in the process. That is indeed what he should try welding to see how it goes.

-Walt



DeeEight said:


> Ummmm 0.035" is .889mm so .9mm would actually be thicker still and thus no trouble at all if he can do the 0.035". The center butted section makes no difference what thickness it is, the welding isn't going there !


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## DeeEight (Jan 13, 2004)

I've stick-welded stuff that thin and other than watching for blow-thrus its not that hard to do. Its certainly not the magical land of skill a lot of the tig-junkies and other doomsayers are trying to make it out to be. You can just as easily get a blow-thru with a tig setup if you're a sloppy welder.


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## WadePatton (May 10, 1999)

Walt got it.


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## Walt (Jan 23, 2004)

*So what?*

Stick weld us up a bike frame and post some pictures for us, and then maybe I'll take this seriously. I get the impression you're arguing just for the sake of argument here.

Nobody is saying he _can't_ MIG this frame, we're just saying it's going to be *hard* and depending on his skill level, might not result in anything safe or rideable. Hence the suggestions to TRY IT OUT with actual tubing of the correct size and wall thickness before going any further. The proof will be in the pudding - if you can MIG or stick weld all the tight clearance/difficult to access/thin walled joints on a bike frame, more power to you. Post some pictures of your creations, and I'll be honestly happy that you proved me wrong.

-Walt



DeeEight said:


> I've stick-welded stuff that thin and other than watching for blow-thrus its not that hard to do. Its certainly not the magical land of skill a lot of the tig-junkies and other doomsayers are trying to make it out to be. You can just as easily get a blow-thru with a tig setup if you're a sloppy welder.


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## jamesdc (Oct 31, 2005)

bmadau said:


> Doesn't SWD bikes mig weld their frames?
> https://www.swdracing.com/images/Pivot.jpg
> 
> Looks mig welded to me. though a DH bike is a far cry from an XC bike...
> ...


nope, they are tig


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## DeeEight (Jan 13, 2004)

Pretty messy looking tig welding. A quick google turned up a number of actual bike manufacturers who do large volumes using MIG welding. For example...

http://www.kwcycles.com/bicycle-chains-india.html


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## hairyharris (Sep 8, 2006)

Yes you can mig a frame. I wouldn't ride it myself, but it can be done. I've been following this thread for awhile now and find it very interesting. I've been welding 20 plus years and some of you are making good comments and suggestions. I personnally would tig it. Simply for the quality of the weld and the appearance. We all know if done correctly it will be strong and last forever. I've migged several thin gauge applications(sheetmetal, floor walls in cars and so on) over the years and like I said if done correctly it will last. But the issue for me is this: using the right welding process for the project. EX. I would not weld boiler pipe with a mig. 

My suggestion is this: learn to tig. It will look alot better and in my opinion be a stronger weld for the frame. 
But do what you want. It's your frame, and enjoy it!!!


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## NEPMTBA (Apr 7, 2007)

JUST WELD IT ALREADY!

Then bondo the welds tell everyone it's Fillet Brazed!

LOL!


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## WadePatton (May 10, 1999)

how are the practice pieces coming?


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