welding question

[wedge40]

I'm going to ask this just for general knowledge of welding. Using mig welders in particular. If I'm looking at Mig adds, I notice they sometime mention being able to weld a certain thickness of steel, 1/4", 1/2" etc. Is the what it's capable of welding in a single pass? And will multiple passes be as strong as a single pass.
Just wanting a little info about welding thats all.
If you were going to weld 1" and 3/4" steel together, would mig give the same results (strength wise) as a stick welder.

Wedge

 

[weldingisfun]

I think you will get answers to your questions at these sites:
Knowledge | Lincoln Electric
Miller - Welding Discussion Forums
Weld Talk Message Boards - Powered by vBulletin
Take your choice.

 

[digger2]

I'm prob. going to get an argument on this,but .......I've been a welder for 33 yrs. and i do know a little about it.
As far as the strength of mig welding compared to stick,i think there are alot of variables,and there really is'nt space here to explain it all.I've seen mig welds done with a machine that was set up wrong that you could knock the weld apart with a hard blow from a hammer.Of course i've seen the same thing with some stick welds,like at the hands of a beginner.
With proper prep. and procedure,a mig weld is usually strong enough for anything.BUT..if i build something that i absolutely,positively want it to hold
like something my life depends on,i'll stick weld it every time.
Sheet metal is one thing,but anything 1/4" and up,i'll stick it.Stick welding has more penetration than mig,and i'll argue that with anyone.But mig does have its place in the welding world,mostly for speed and appearance.I have nothing against mig,i have one myself,along with a stick machine and a tig.
All these machines have there place,it just depends what you are doing.
Everybody has there opinion,this is mine.......Digger2

 

[ray66v]

Digger is right, yes you can weld thick metal with a mig. But, it will require many passes and heat build up can be harder to control (think warpage). With proper beveling and sometimes preheat I have welded some really thick steel with a mig. Keep in mind unless you buy a heavy commercial machine you will find the thermal overload protection shutting you down as you hit the end of the duty cycle. (This can really slow things down). Migs are best suited for sheet metal work, (easy to control in tight places and making critical plug welds). If you want to do a lot of heavy fabrication work, though it may take a little more practice to use, a stick welder will be more efficient and can be much faster. There is a pretty big difference in stick welders as the price in creases. A good machine that can weld with DC and has an arc starter would be ideal but, your gonna pay for those. If you don't mind how "pretty" your welds look you can certainly get by with a basic AC machine.

 

[Sully2]

I'm going to ask this just for general knowledge of welding. Using mig welders in particular. If I'm looking at Mig adds, I notice they sometime mention being able to weld a certain thickness of steel, 1/4", 1/2" etc. Is the what it's capable of welding in a single pass? And will multiple passes be as strong as a single pass.
Just wanting a little info about welding thats all.
If you were going to weld 1" and 3/4" steel together, would mig give the same results (strength wise) as a stick welder.

Wedge

Properly done...by a fully compentant welder..a weld done with a "wire fed welder" ( MIG or using fluxcore wire) will be every bit as strong as the same sort of weld done by a stick machine...PERIOD

Any wire fed maching fully capable of doing 1/2" steel in a single pass is going to cost you a WAD..and I do mean a WAD. Capable of doing 3/4"...and or 1"..in a single pass...plan on trading the deed to your property for it cause " you aint got enough $$$"

A multi pass weld certainly CAN BE as strong as a single pass..BUT..the chance for "bad spots" increases GREATLY.

My own usage is steel 3/16-1/4 with the occasional 5/16's thickness..and I bought a wire fed machine capable of doing 1/2" thick ..single pass..using FLUXCORE wire ( it penetrates deeper..and I have to work outside..where the shielding gass for MIG would be blown away)

If you intend much 3/4-1" stock welding..buy a large stick welder ( I prefer DC stick machines) and a stack of large rods.

 

[Sully2]

...
Sheet metal is one thing,but anything 1/4" and up,i'll stick it.Stick welding has more penetration than mig,and i'll argue that with anyone.

"Penetration" is exactly that..penetration! Any welder of any sort..capable of 100% penetration will create equally strong welds. In fact.."some" welding wire used for MIG machines have HIGHER tensile strength than rods made for stick machines. Hence a properly made weld using that wire would be STRONGER than the same weld using a stick machine

 

[ray66v]

If I may speak for digger; I believe what he means is there is a propensity for mig welds to have "cold starts" particularly on thick metal. A Cold start will limit penetration and sometimes in the case of a small weld area, can leave you with a weaker weld than if it was done properly. A large enough mig with heavy enough wire and or proper preheat, can limit and or eliminate this problem. Using a stick welder with a good size rod is the best way to, in most cases, get a good weld going the fastest, particularly at home on heavy material.

 

[Mickey_Fx]

I'm not a pro by any stretch but I have to side with Sully. IMO operator knowledge and proper setup has a bigger impact than the source of heat.

Don't know how many of you watch either HOW'S IT MADE or SOME ASSMBLY REQUIRED but in the past week they had a segment on a company that makes HUGE earth moving equipment. Many welded sub-assys made from thick plates fixtured and welded by robot welders. No stick welders in use.

For home equip and what the typ person can afford, a stick welder suitable for heavier work is more affordable. YMMV

 

[wedge40]

Wow, Thanks for the replies.. I didn't think about peoples "preferences". People keep mentioning preheat? I'm guessing this would be getting the two pieces of metal fairly hot before starting to weld (MIG). Maybe in the red or orange range. Just a guess.

Wedge

 

[ray66v]

Preheat is not at high temperatures, it is just a kick to get things started faster. The preheat can help stop a large mass from sucking all the heat out of the weld as you start it. I guess 500 degrees will usually do the trick. Keep in mind that if you are working with hardened steel you do not want to use a lot of heat on it.
I have seen structural steel being welded (vertical beams on a skyscraper) where they had propane rosebud torches on two sides across from each other warming. And two welders were welding on the other two sides across from each other.
Beveling the edge of the steel so that the thickness your working with is within the ability of your machine is another way to get a good start. Then as you make additional passes the metal will be heated from the previous passes and the welds, (especially from inadequate equipment and will flow better). A good welder can do this with a cutting torch and produce something very quickly that would take forever any other way. (I can't do it).
Welding is an art and is an extremely complicated science if you break it all the way down to the textbooks. But, like most things if you know the basics and have someone who you can ask for help when you need it, you can get by most of the time.

 

[2manyrocks]

There are many variables that go into making a good weld. The machine is part of it, but the skill of the operator is a bigger part. If you gave me the best Indy 500 car ever made, I couldn't win with it because I don't have the necessary skill or experience to drive it. If you can learn from an experienced welder, it will help you tremendously in picking the right equipment, the right electrodes and in the welding process itself.

 

[jklingel]

I'm a back-yard, used-to-weld-professionally for a few yrs, but am not super experienced. I agree about the large DC machine for heavy plate, though. Stick welding is pretty versatile. You may want to check another forum, too, like the Garage Journal, in the fabrication section. There are more pros there, but I don't think you'll hear much different than these guys have said. There is one "gent" who tends to blow off a lot of air there and is flat rude if you disagree, but other than him, I find it a pretty good place to ask. (The guy does know his stuff, though.) j

 

[ROUSTABOUT]

Welding is a lot of "hands on". I can tell you how to ride a bull, and you may think you have it all understood, but until you get on one of them, you won't fully understand. I am a steel fitter, and I think you can learn all you want to learn, if, you want to learn. When you heat steel until it is good and red, it will be soft even after it cools. Usually when building drilling rigs, the pre heat on 4" plate was usually 350 deg. or so. Pre heating also spreads out the heat, whereas when welding, the electrical short caused by the electrode super heats a small area. On something thick, going slow and keeping it from getting too hot will minimize distortion. If you weld it fast and stay after it, welding bead after bead and get all that steel very hot, it will move, or draw, as it cools, and on thick steel, that is a bad thing, because it is hard to get it back in the right position. I had to mark all the welds, I even numbered the order of how I wanted it welded, and my welders knew what I wanted, and it always worked out really well. I love fitting plate steel, it is my passion.

 

[dieselcrawler]

I've had a stick welder for years... the ol' man was showin' me what to do when I was ten years old... never had any formal training, just workin' with this and that, fixin' farm stuff, and built a few deer-bashin' bumpers for my trucks over the years... nothin' broke that I thought would hold, and everything I thought would break, did.

Buddy of mine let me keeps his MIG w/gas at my garage... now geesh that critter is nice... been makein' exhaust systems for my ol' trucks... super nice for thin metal... gonna do some cab corners on another project truck soon...

Each type of welder has it's place... it's nice to be lucky enough to have both at my disposal... the areas they work well in overlap, and which one I'd want first is a toss up... I'd rather learn on a stick... I think it makes you a better welder...

Operator skill becomes the bottom line...

Greg

 

[CRAFTBENDER]

I believe there is more room for error with a mig. I have seen welded pieces that fell apart that had a nice bead. I mostly tig weld. There is no doubt with tig because you can see the puddle. An experienced welder can get a great weld with mig. It's all about preparation, proceedure, and knowing what you are seeing. By the way, when I stick weld, I use my foot pedal and high frequency start so I can vary my heat and control.

 

[jmcalli]

Yes, manufacturers rate their MIG machines at single pass weld capability. I have a Millermatic rated for up to 1/2" steel, and I have welded 1/2" steel in a single pass. At that output the duty cycle is about 30%, but it's not a problem. I don't think I've ever needed to weld for three minutes straight but even if did exceed the duty cycle, the machine would shut down before it overheated.

 

[bobodu]

What bothers me about MIGs is that Joe Schmoe goes to Harbor Freight and buys a $200 MIG and expects to be able to build a safe FEL with it.Or a 10,000lb. trailer or a motorcycle.My own personal belief is if ya gotta ask,you better go stick.

 

[Sully2]

What bothers me about MIGs is that Joe Schmoe goes to Harbor Freight and buys a $200 MIG and expects to be able to build a safe FEL with it.Or a 10,000lb. trailer or a motorcycle.My own personal belief is if ya gotta ask,you better go stick.

And inexperinced welders wont do that with an El Cheapo stick machine? C'mon dude!!

 

[Sully2]

I'm going to ask this just for general knowledge of welding. Using mig welders in particular. If I'm looking at Mig adds, I notice they sometime mention being able to weld a certain thickness of steel, 1/4", 1/2" etc. Is the what it's capable of welding in a single pass? And will multiple passes be as strong as a single pass.
Just wanting a little info about welding thats all.
If you were going to weld 1" and 3/4" steel together, would mig give the same results (strength wise) as a stick welder.

Wedge

If you go various places on the internet ( Like to Hobarts webpages) you can download the PDF files that are the users manuals for their machines.

The answer to your question about can it weld what it says it can ( thickness-wise) is a yes and a no. A Hobart HH140 CAN weld 1/4" steel..but NOT in a single pass..it takes more than one pass to do it ( per their own manual) Multiple passes on a weld had better be as strong as a single pass..or there are many things that are going to fall apart!!

As far as a 1" thick piece welding to a 3/4" thick item....In either case the joint will have to be prep ground..and most probably pre-heated...but with the PROPER SIZED wire fed welder ( and of course a guy that knows what he is doing...) it can "easily" be done.

Never forget that a high quality "stick machine" costs about the same as an entry level MIG welder!! And if your intent is working on tractors; trailers; farm machines in general...you'll probably be a lot better off with something like a Hobart ( as an exanmple) Stickmate thats AC and DC also.

Being proficient at welding..and choosing the right rod for the job..a Stickmate such as that AC/DC model will weld anything you'll ever come across

 

[bobodu]

And inexperinced welders wont do that with an El Cheapo stick machine? C'mon dude!!

"DUDE"....the very nature of stick is such that even though the weld may be on the ugly side,it's far more likely than an inexperienced welder can make a stronger weld.You ever wonder why stick is the first thing they teach? I am able to use either process,but my MIG sits there most of the time because I want things to hold.
As far as cost goes,my Lincoln AC225 cost me $85 and my Lincarc welder/generator was given to me.