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  1. Dec 19, 2017 #21

    Little Scrapper

    Little Scrapper

    Little Scrapper

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    When you said "patently obsured" I'll admit that pissed me off considering I've been pushing Oxyacetylene welding since day one. So.i found that really bizarre to be honest.

    I thought I explained it quite well but maybe not.

    Look, I'm not excited, worked up or flying off the handle. My writing comes off like that, that's not who I am. I'm pretty well known for being calm and level headed. I'm just a really bad writer when it comes to typing messages through my phone. Maybe it's because I'm always in a hurry and have multiple things going on and I write short?

    The only thing that really drives my crazy is when I'm taken out of context, I really hate that.

    Anyhow, I wasn't yelling at you.
     
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  2. Dec 19, 2017 #22

    TerryM76

    TerryM76

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    From my perspective, once a person has mastered the tacking process with MIG they could tack up a framework rather quickly and then use either O&A or TIG for producing the actual product.
     
    Last edited: Dec 19, 2017
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  3. Dec 19, 2017 #23

    Turd Ferguson

    Turd Ferguson

    Turd Ferguson

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    MIG is certainly fast. I don't think I'll ever master MIG in tacking or welding, just not enough years left.
     
  4. Dec 19, 2017 #24

    don january

    don january

    don january

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    For the non-welders out there Have you ever wondered what MIG or Tig stand for?
     
  5. Dec 19, 2017 #25

    Hot Wings

    Hot Wings

    Hot Wings

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    Metal Is Glue

    This Is Gorgeous

    :gig:
     
  6. Dec 19, 2017 #26

    Turd Ferguson

    Turd Ferguson

    Turd Ferguson

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    I always thought the guys that coined those acronyms were trying to compensate "Mine Is Giant" and "This Is Giant"
     
  7. Dec 19, 2017 #27

    Winginit

    Winginit

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    I think Scrap brought a worthwhile problem to everyones attention. I have to agree with him that Mig is probably not the best process for an Amatuer welder to use on thinwall tubing. The welds in the pictures he provided are terrible and of questionable reliability. First thought is that anyone purchasing a kit should ask what welding process is being used, and no matter what process it is, verify the quality of the welds. It really does not matter that someone tells you they are using Tig or O/A, it still has to be done well. Many sloppy welds will still hold and never fail, but if you are paying for professional work...it should be to professional standards. If you are doing it yourself and aren't very good at it, then weld a few test pieces and cut them apart to verify penetration. Use a hammer and see if you can break them.

    As far as Mig tack welding goes, a very knowledgeable and well known Metal Fabricator said on his training video that a Mig produces a harder weld than a Tig. He was talking about welding thin panels and the fact that it was harder to grind a Mig weld flush and the additional heat during grinding could cause a panel to warp....so he preferred Tig welding. Now both processes use the same composition of welding wire, so I don't understand why one would be harder than the other, but thats what he said. I do know that many people tack with a Mig and then Tig later.

    I think the thing that allows a professional company to Mig weld is using a machine that has a "Pulse" feature. The machine can be adjusted so that it varies the current while welding. Not sure if it completely turns the current off for a milisecond, or just reduces it to a minimal current and then back to the normal setting. The machines that employ this feature are adjustable and you can get as few as 1 pulse per second up to several hundred pulses per second. That allows the base metal (tubing) to cool slightly and reduce the overall temperature imparted into the weld. In other words you have the full heat to penetrate, a little cooling , and back to full temp again. Most Mig machines don't come with a "Pulse" feature until you get to the more expensive models. The thought that someone could manually adjust a Mig correctly while welding would be extremely difficult if not impossible. They may however realize they are too hot or too cold and make an adjustment while welding. I did see on a video where the instructor told a student to begin welding and adjust the amp knob while making a weld to see if the weld got better or worse, and bacon sizzlin sound improved.

    Good post Scrap.......

    https://www.youtube.com/watch?v=wygvhokaniU

    Watch the first minute of this video to see a close up of the pulse weld transfering process.

    https://www.youtube.com/watch?v=WTiCxszwW4I
     
    Last edited: Dec 19, 2017
  8. Dec 19, 2017 #28

    Winginit

    Winginit

    Winginit

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    After looking again at the pictures Scrap provided, this second picture seems that the welder was basically trying to imitate "Pulse" welding.

    FB_IMG_1513633610180_2.jpg

    I have done this many times when welding with my Mig (and too lazy to go get the Tig). When welding something that is non critical but kinda thin, or something that has a gap that needs filling, I do this. What it consists of is making an initial tack and releasing the trigger. Then make another tack that slightly overlaps the previous tack.....and on and on. It isn't beautiful, but it works. If there is a gap, I get the first initial Tack and then try to build from that with additional tacks until the gap is filled. Then if possible, weld again from the other side with a conventional weld. Now go back to the first side. If its unacceptable, I can now grind it flat and put a conventional weld in place since no gap exists now. This kind of multiple tack weld can be done when installing sheet metal on restored vehicles. An O/A may input too much heat into the sheet metal and warp it, and many restorers don't own a Tig. Its acceptable to do something like that when using it in non-critical situations. Apparently this welder tried to apply the process in a critical situation, and while it may hold up, I would not want to rely on it.

    When welding something thin, continued application of heat may/will cause warping even though its the correct temperature needed to fuse the metals. Pulsing helps control that heat for a continuous weld, but on sheetmetal you may still have to weld short sections and stop for cooling. It does however allow somewhat continuous welds rather than tack,tack,tack,tack,tack..........Pulse is really kind of an automated tack weld that allows better control of the flow and melding of the metals because it happens so quickly....something not attainable by hand action.
     
    Last edited: Dec 19, 2017
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  9. Dec 19, 2017 #29

    don january

    don january

    don january

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    MIG -manual inner gas, Tig -Tonguestein inner gas. Why is Mig not alright? is it perocity in the weld or just to hard to control? Biggest question is why is Mig a bad way to go? also what makes Tig so much better? it is usually the same gas applied. (Argon) As a welder of like forever it's all about the puddle and how it is layed? Can a person see if you have 100% of penetration in the weld? As far as tacking it is all about holding the piece until the weld can be applied. Can the Tack contaminate the weld? Pre- heating what does it do to the metal that aids in the weld? "On and On" bottom line is either you can lay a good pass or you can't and will it hold at IAS. If you can't find the right strength get someone who can......
     
  10. Dec 19, 2017 #30

    pictsidhe

    pictsidhe

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    Welds don't need to be pretty to be strong, but those welds don't look good to me, either. Penetration looks poor. I wouldn't try MIG-ing a fuse together. My tack welds are never pretty, until the final weld puddle eats them. Not having them too big is key there.
    I love OA too, but haven't had a rig for a long time.
     
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  11. Dec 20, 2017 #31

    Winginit

    Winginit

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    Don, I think the thing here is that material thickness.....or the lack of thickness is the "elephant in the room" that makes airplane tube welding more challenging than most other general welding. In general, welding thicker (3/32- 1/2") is much easier because you can lay a decent weld and have a little room for error. The O/A will become more challenging as thickness increases. So the thing to consider here is that when welding with O/A, a builder will typically use a smaller than normal torch with better control of adjustability over a smaller heat range. A Tig torch kinda does the same thing. There are different size Tig torches and you have an adjustable power setting "during the weld process". As you know, the O/A needs to be pretty close temperature wise and you move it farther away if you need to lose a little heat while welding. Both of those types of welding allow a builder to exert some control " during" the weld process. With Mig you have a virtually immediate temperature influx imparted into the weld area and must move quickly along the weld path. Mig is known to be fast welding process, but that kinda works against a welder who is trying to do small difficult areas. You have no real control over the heat affected area other than your initial setting and wire size. The lack of that control is why Mig (without Pulse) is not a good choice for airplane tubing.(IMHO)

    Moving to O/A, builders often get O/A to hold things together but are not very adept. They may not blow holes in tubing, but many of those welds are not something that I would want to trust. No matter which process someone chooses, they should try to at least make a proficient weld. It doesn't have to be astetically beautiful, but it should at least have a semblence of decency......
     
  12. Dec 20, 2017 #32

    Lucrum

    Lucrum

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    I started with a MIG machine, mostly because it was supposedly easier to master.
    In hindsight, I'd should have gone with a TIG to begin with.
     
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  13. Dec 20, 2017 #33

    Winginit

    Winginit

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    It takes more effort to become "competent" with a Tig. There are extra settings to learn the name of and their purpose. Its a little confusing at first. Then there is a world of applications that use special features of the machines, gases, Tungstens, etc. The thing is the average builder sometimes gets overwhelmed by all of this stuff. Then there is the mystique attached to becoming a Tig welder and chasing the ever perfect bead. Its kinda like your first few flying lessons. There was so much to learn and comprehend, and the pressure to not look like an idiot while doing so. Flash forward, and as you became more familiar with the controls, the terminology, and the effects of your inputs, things began to come to you more easily. Now some of the pilots progress to the point where they are really adept at flying. Many others only maintain sufficient skill to fly occassionally and may get rusty between flights. Well, welding is somewhat the same situation. You don't have to be an "Ace" welder who lays a perfectly formed and astetically perfect bead every time. Once someone begins to weld they will have a learning curve, just like flying. You can attain whatever advanced level you desire to attain, again just like flying. What you (anyone)will eventually find is that you seek your own level of comfort in the ability to weld. Once you practice a little, you will decide that most of your welding on the airplane will be similiar. By that, I mean you will be welding thin steel to thin steel. You will find that several of those confusing terms and knobs become second nature, and you always (pretty much) leave them set and don't touch them. Things get easier and you only fool with a couple of things because you have standardized your set-up. Things get somewhat easier just like flying. Now, when you fly, you also know that sometimes conditions change and push you to your limits. Well, if you move on to welding other things, you will have to get used to moving a few more switches or knobs, maybe change the gas type, or use a different tungsten. Its all on a chart, so you make those changes and try welding something different. The thing is that for homebuilt aircraft welding, most of the time you have to do minimal changing once you get everything set up for that type of weld. I think the "mystique" of Tig welding intimidates many people, and they don't give it a try because they think they have to be "superwelder" to do that kind of stuff. Its never too late to buy a Tig, but I would keep the Mig for other stuff.
     
  14. Dec 20, 2017 #34

    TFF

    TFF

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    I find it harder to MIG. There is a certaint ease of point and shoot but you don't have personal control. OA and TIG you melt holes which proved you can get it hot and back up from there. When you melt and don't make holes you are on the good side. There is no holding personal speed up to get it to fill in, MIG just shoots and you better keep up. The Champion welders sit with their back to the welder with their hand on the knob and is constantly twiddling it as he goes around the clusters. I would hate to take that welding test. Everyone wants pretty welds , but the default to the types is really what matters. Most ugly OA/TIG welds are strong. Pretty MIG can be weak masking the real joint. Really hard to make a pretty OA/TIG that is not right.
     
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  15. Dec 21, 2017 #35

    Marc W

    Marc W

    Marc W

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    I just want to say that this thread has been very informative. I have an OA rig and know how to use it but I am planning to get some type of electric welder and really know nothing about them. Thanks to all the knowledgeable people who posted here.
     
  16. Dec 21, 2017 #36

    stuart fields

    stuart fields

    stuart fields

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    Re: MIG. vs TIG

    I've TIG welded 0.032 aluminum with some success. I've also TIGed 4130 to my satisfaction. I've MIG welded some thin steel and am glad it is not in a structural or critical application. I find the TIG to be very much like O/A. I can strike the arc and watch the puddle form showing me that I have applied heat to the parent metal and have some penetration to both pieces. MIG on the other hand, and I don't have that much experience, seems to require me to be moving when the arc strikes not allowing me to see the quality of the puddle where I start. I'm never sure just how much of the MIG puddle I see is made up of the parent metal and how much just the melted wire. The more I learn, the more I'm aware of how much more I need to learn.
     
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  17. Dec 21, 2017 #37

    Little Scrapper

    Little Scrapper

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    I learned MIG & TIG in schools. I remember how tough MIG actually was at first. Everyone thinks it's easy because you can buy a $300 cheap unit at Home Depot and squirt stuff together. It's sort of an illusion because that group never has had to past weld tests and have samples X-Rayed.....an entirely different story.

    A really good MIG welder will have superior controls to regulate the wire feed rate and the heat. The better the welder the better the adjustability is. And what can create an additional challenge is the guy pulling the trigger because he regulates
    travel speed. Combining travel speed with wire feed rates can also regulate temperature because and dwell time etc.

    I'm decent at MIG if I can practice a little bit before laying critical welds but I've never been great at it.

    In my formal schooling I focused heavily in TIG because in power plants I did things that required it.

    If anyone has even been sorta good at Oxyacetylene there's a high probability that person will do very very well at TIG welding. It's a very natural progression.
     
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  18. Dec 21, 2017 #38

    Chris In Marshfield

    Chris In Marshfield

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    I can go with that. I learned to gas weld first (haven't used it in practice, but learned it). When I took a TIG class a month or two ago, I found that it felt a lot like O/A. You hold the torch a bit differently (depending on your gas torch), but otherwise it's a lot alike. The source of the heat just comes from electricity instead of a gas flame.
     
  19. Dec 21, 2017 #39

    Winginit

    Winginit

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    One thing I enjoy about Tig welding is striking the arc and watching a neat little puddle begin to form. Its kinda surreal because you can just hold it right there or begin to move along. Its like a magic wand and you quickly find that you can adjust whats happening with a move of your foot or your finger if you have a hand control. There is this neat little concentration of energy just waiting to do your bidding. As mentioned above, its very similar to O/A welding but you can instantly change the temperature as you move and need slightly more or less heat. It is much more controllable than other types of welding and much more precise in placement of the heat. Once you get used to melting a bead and moving your hand steadily, you move on to using your other hand to dip a rod into the edge of the puddle. Since there is an electric tip (Tungsten) creating the "flame", you can contaminate it by touching the base metal or sticking your rod too far and touching the tungsten. Thats a problem you don't have with O/A, but its a similar way of welding. You WILL do this a thousand times while learning to Tig, but in the end you will love Tig welding once you get a little experience.
     
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  20. Dec 21, 2017 #40

    Pops

    Pops

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    I welded boiler tubes in coal fired power plant for about 15 years. Went to Babcock and Wilcox's welding school. B&W makes the boilers and have their own steel mills and tube mills. I worked for their construction company building their boilers. Also worked for Foster Wheeler and Union Boiler company building power plants and installing pollution equipment. Some of my family started Union Boiler construction company in 1952 and sold out in 1985.
     
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