Why do people TIG weld DOM tubing? All the specs I see on it they call it a mild steel so it seems to me like MIG should be fine. What I'm talking about is for radius rods and applications like that. Actually it seems to me like MIG would be better. Am I missing something here?
tig looks nicer , mig will be fine if done properly on my `28 tudor , i made rear ladder bars that copies of pete & jake's...the mig welding has held up fine for 13 years
with a Tig you would get a better looking weld ( with pratices ) with out any grinding to the finished piece a Mig will work if thats all you have
Think about this like Records to CD's to MP3's, Why put a record player in your car when technology has surpassed, well...I guess this is the wrong site to say that on, but long story short.... Tig is state of the art, best possible quality. On radius rods, where you have one weld wrapped around 1 weld bung......you don't want the bung to pop out cause it was welded too cold or whatnot. If your a cert'd welder....you know what you can and can't do......Carl Hagan TIG is much more pure of a weld than MIG
Today's Friendly Safety Reminder: When welding a tube, make sure you don't pass anything you value past the opposing open end of the tube. The hot gasses shooting out of the tube during the weld will melt through your hand quicker than you even realize there is an issue. Yep - done that.
We have a guy nearby that does air ride chassis of the highest order. His MIG work can easily pass for very good TIG. The most technical reason for the different requirements is the manual control of heat v.s. filler volume provided by TIG. MIG does it all on auto pilot so it's easy to miss a lack of penetration. I have both processes all over my chassis. My reasoning was primarily appearance.
Thanks for the replies, guys. I have hundreds of hours of experience with MIG so I am 100% sure I can get a stronger weld with MIG than TIG. I understand why TIG is used on Chromoly tubing and I always assumed DOM was similar but after checking it out I found DOM was mild steel so that's why I asked.
I have only played with tig once but i suspect it is like why I like gas welding better than mig welding. Tig welding is not that different just an arc rather than a flame. As you learn to weld and develop a feel for it sometimes you find a sweet spot and can do beautiful welds . This is pure joy and I suspect tig guys find it similar. Before I was forced to use a mig because of the rules I used to say Mig welders are for folks who cant weld. I would love to learn tig but simply cant afford one at the moment and dont have a good enuf reason to have one yet. A buddy though, bought one and is not a welder so he said he was going to bring it here with a bottle for me to use. I would welcome the oppourtunity. In the meantime I just grab my coat hanger and oxy acet torch and make some more neat beads. On a real good day i dont need the coat hanger hardly at all.
Here's a reality check for all of you. See those NASCAR cars circling the 1-2 mile ovals at 200 miles an hour? See them flip (sometimes more than a dozen times, become airborn and crash in a mass of twisted metal and the drivers unbuckle an walk away? Those chassis are mig welded. Mig is a very attractive method to join metal in a high volumn environment and the guys doing it will normally achieve 100% penetration on every joint. Its all about taking cold starting process and developing a technique that minimizes that characteristic. When I did the roll cages for Howe Racing Enterprises it wasn't uncommon to produce a dozen frame/cage assemblies a week. After examining dozens fo crashed cars I never had a weld fail. If the joint came apart it was always an 1/8" to a 1/4" away from the joint and the materiel simply pulled apart like taffy. Cutting a crossection of the joint you couldn't tell the base material from the filler. Frank
Tig makes freakin nice welds! Too bad I have no talent! I am practicing, but it is going to be a while, and I will NEVER be a tig artist... Just the way it is..
Don't confuse a pretty weld with one that functions properly. Sure, I'd love to be able to TIG better, who doesn't? Lack of experience and time spent on a TIG is what keeps me with my trusty MIG welder. I'd use a TIG more if I had the time to learn it better and practice. I've seen just as many nice looking, but poor penetrating TIG welds as I have MIG or Gas Welds. I've built chassis, rollcages, suspension components with a MIG and never had a weld failure, even after a serious crash. Opinions are like assholes, and everybody's got one, so take it with a grain of salt.
i can tell you from first hand experience that all tig welds are not created equal!! i bought a straight axle from a reputable manufacture for my henry j and after about 3 years on the road, the king pin boss broke right off at the weld!! i will not tell you who i bought it from, so don't ask. i will say this, someone was watching over me that day. i was going down the fwy at about 80 mph in the fast lane one saturday morning and then i said, "why am i going so fast", "i am not in a hurry, slow down". i moved over to the second lane and then the wheel just folded under the car and i slid into the right shoulder at about 50 mph and stopped. i put an arc weld on that sucker like you wouldn't believe and it's been together for awhile now!
I am not a welder, not even close, but recently on another forum they were discussing MIG'ing chrome-moly cages, and the bottom line according to the pros was that the weld needed PWHT. Post weld heat treating. Heating the area approx 2" from the actual weld to re-stabilise the metal. The MIG is very heat intensive and very localised, therefore the tube will break just away from the MIG weld. Bruce.
Tig was perfected for practical use in the late 1930's to early 1940's for the aircraft industry for welding non ferrus metals. Know widely as Heliarc because or the use of helium. Requires a distinct talent and high skill level. Hand-eye coordination vs Both hands and a foot - eye coordination. Mig was perfected for practical use in the 1959 ish. Its just about as Automatic as it gets after the machine is set correctly. Sellecting the propper gas and wire, and machine settings for the application is critical if weld qualities are critical. Mig was designed for mas-production and speed. Easily taught to factory workers who have been replaced by robots. Plenty of mig welded aluminum out there also. Fulx core was around a bit later for use outside in ship yards and other uncontroled enviroments. The type of gas used will greatly affect weld quality. Sure there are "fits all" gases that will get the job done. Depends on what you are welding. Complete books have been written on this subject http://www.thefabricator.com/Consumables/Consumables_Article.cfm?ID=1024 is just a short article on the subject and more than most want read. I have seen plenty of 6010 or P-5 beads laid down with a $100 AC cracker box machine that are just as pretty as any $10,000 tig machine beads, with the use of some anti spalter. Mig welds need to pass the same destructive tests to certify and are plenty pretty. I have also seen absolutly beautiful mig beads that you could knock the whole fillet bead off with a chisel. Ancient swords were made by heating different metals in a coal furnace pumped full of air and hand beating them together. They are indestrutible and very pretty and about as pure as metal gets. If it is an alloy better off to tig weld it. Bottom line is it is the operator and material in question not the process.
TIG isn't necessary on CrMo tubing, there are 4130 light aircraft out there that have been MIG'd for a long time. The post weld stress relieving is necessary with CrMo. The nature of the metal is to harden at the transition point of the weld. The area right next to your weld is much stronger, read brittle, and the joint will fail right there. You can fix this by heating the area to a dull cherry red and letting cool slowly. This returns the area to a normalized state. If you are using 4130 for it's ultimate strength, you will need to have the assembly heat treated post fabrication. If you just normalize, you end up with a structure that is only marginally stronger than a 1018 mild steel one. The heat treating can get you way past mild steel.
I remember reading a book on the history of the Indy 500 a few years ago. I don't remember the builder's name (Kurtis?) but the very first car to be entered with TIG welds on the chassis was bounced out of tech because it was widely accepted that TIG was not safe for structural welds. They made the builder cut all the TIG welds out, then re-weld it with a plain-old stick welder befroe they'd allow it to pass tech. Now people assume TIG is some magical way to attach one piece of metal to another and stick or MIG welding is for hacks. That kind of thinking was wrong then, and it's wrong now. Good welds are not dependant on the machine being used.
THE ABOVE STATEMENT PRETTY MUCH SUMS IT UP!!! all of these threads about TIG is better then MIG are getting pretty redundant dont you think. If you know what you are doing then there is nothing wrong with MIG in its perspective applications!
I am pretty good with gas and a mig, but have never used a tig because I don't have one or access to one. I have taken a few welding courses at the college level and can say that a good welder is a good welder - doesn't matter what they are using - gas, mig, or tig. If you know what you are doing and the prep work is done right - all of them will do a good strong weld.
The Jalopy Journal
