Tig welding Chromolly tubing

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  #1  
Old 02-01-03, 01:03 PM
Portable Welder
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Tig welding Chromolly tubing

A good buddy of mine is really into drag racing and has been doing some race car fabrication for several guys and he wants to start doing chromolly cages instead of mild steel.
My buddy Matts brother is the head engine builder at a shop that does big dollar race- show cars for people like Jay leno and Tim Allen, and this shop is also tied into doing General Motor proto types for the magazine tests.
Well the problem is, is that the tig welders at this shop, that weld chromolly every day told Matt that the weld only has to be half the thickness as the tube thickness.
I told matt that I think they are wrong, and that the weld has to be as thick as the thinnest pc. that you are welding, and for instance if you are welding a 1/2" plate to a 1/4" plate you need to have at least a 1/4" fillet weld.
I however do not do race car work because it does not pay well enouph, unless you are a big name in the racing world.
However since they work in a big name shop and I'm just a rinky dink welding shop maybe they know something I dont.
I would like alot of feed back and please advise me if I'm wrong it would'nt be the first time.
 
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  #2  
Old 02-01-03, 03:28 PM
Skaggydog
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some feed back

All the welding codes and specifications I've seen state that the weld size HAS to be within certin percentages of what the weld symbol calls for (which is usually approved by an engineer). AWS D1.1 states that a fillet weld does not have to be bigger than the smallest thicknes, and that a lap weld on a 1/4 plate can not be bigger than a 3/16 fillet. A butt weld has to be full penatration unless a size is given on the symbol.

I would gess the racetrack would be the one to say how the car should be welded. If it was my car I would insist on full pen butts and well contured fillets with no undercut or craters
 
  #3  
Old 02-01-03, 03:57 PM
Portable Welder
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I always see very narrow weld on many chromolly tig welded cages, I tell my friend not to try to get a narrow weld worry more about deposition, some of the cages I've seen over the years look like the guy did alot of fusing. give me your thoughts on this.
 
  #4  
Old 02-01-03, 04:10 PM
Portable Welder
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I told my buddy that the guys welding the race cars never see the cars after a crash, but when I weld on Heavy equipment it is tested right away and if its a bad job your refixing it the next day.
I'm curiouse Skaggy dog or who ever, do you ever have old men tell you that a mig weld is not as strong as a stick weld, I always have to lauph at those guys they are obviously not cert. welders.
I've repaired more heavy equipment after a stick welder tried to do it than I care to say, not that a stick isn't any good but they barry so much flux in they're weld its not funny.
 
  #5  
Old 02-01-03, 04:47 PM
NutAndBoltKing
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There are, generally speaking, three main sections to any scratch built tube steel framed race car. The front clip, roll-and-crash cage, and rear clip. Each serves a different purpose and assembly requires different welds.

Roll-and-crash cage: An automotive tube steel roll-and-crash cage protects the driver because of the inherent ability of redundant steel framed structures to withstand extensve damage from extreme events WITHOUT progressive collapse. All the welds, irregardless of the type of race car, in a roll-and-crash frame must be the full thickness of the thinnest piece.

Front and rear clips: The other steel framed sections of a race car; the front and rear clips, are also redundant steel structures, but they are built to withstand extensive damage from extreme events WITH progessive collapse, so they are also known as crumble zones, designed for the absorbtion of dynamic crash energies. The only welds in the clips that will resemble the full welds found in the roll-and-crash cage are for engine and axle mounts. The other clip welds are half or quarter welds which will allow progessive collapse.

Not all welds in scratch built tube steel frame race cars can be full welds because welding eutectics reduces inherent strengths of metal.
 
  #6  
Old 02-01-03, 05:21 PM
Portable Welder
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You are correct, Nut and Bolt King, you are right about the crumple zones, the guys in the race car shop were refering to the roll cage. I think I should give nut and bolt king they're address so he can speak to these pro tig welders and set them straight before some one dies thank you Mr. nut and bolt king.
 
  #7  
Old 02-01-03, 06:19 PM
scrapiron
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Regarding the thought that mig welds are not as strong as stick welds, I've heard this also, even had a fellow tell me not to use the mig for his repair, that it wouldn't hold. I think this comes from people using migs improperly, not enough heat. They get a pretty weld but not enough penetration.
I found nutandboltkings information very interesting. Makes sense to me.
 
  #8  
Old 02-04-03, 04:05 PM
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I think your right SCRAPIRON, there are people who will do vert. downs and run a wide pass which causes a thin week weld.
I have had people tell me the same thing that they want it stick welded because mig is not strong enouph. I mig weld it any way and they never know the difference.
 
  #9  
Old 02-11-03, 08:43 PM
S
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I am not giving my wire feeders away just yet. What a Godsend to the speed and ease for repairs and fabrication. Saves so much fab time to be able to fill gaps easily and quickly. Also for light metals. The only time I stick weld in the shop would be some alloy like nickel. If I did a bunch on the road I would have it there too. I got a lot of stuff I do that takes a rod here or there. But I get spoiled in shop with plasma and feeders. Details are so much easier. I see a farm shop that had new 250 feeder sitting in the corner of the shop for 2 years. They sloppy stick welding everything. NOW,,,,What temperature does silver brazing alloy melt at and can I use it to solder a broken stainless tubing fitting? This thing could see up to 900 degree service. It would sure be easier than welding it up. Anyone use mini tig and how low could you go with a 1/8th tungston? I have some parts to a 1/16 torch maybe. Straight argon on stainless?
 
  #10  
Old 02-14-03, 03:31 PM
Portable Welder
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Years ago I tried to braze a stainless steel sink and ruined it.I've came a long way since then, but I'm not sure if you can use silver brazing on stainless, I Tig weld all of my stainless, any time you use a tig welder you want to use pure argon, I know they use to use Helium years ago but was told argon is the way to go because it doesn't have the tendancy to rise and leave your molten puddle without shieding gas.
As far as welding thin stainless, I recomend that you use a small 1/16" tungsten and a smaller rod to match it.
 
  #11  
Old 02-14-03, 03:51 PM
scrapiron
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If you soldered it what were your results? I was kind of thinking along the same lines as Portable Welder, using the tig.
 
  #12  
Old 02-14-03, 08:59 PM
S
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Is a long story,, It didnt solder well and I got to lazy to change out wire and gas in feeder and didnt have 1/16th heliarc, so like a dummy I hit it with a stick and burn a hole in it. So,, thought of all the fixes, then talk to the engineer and mechanic and decide to junk the part. I am not even going to use it. It was air injection system on Ford pickup, I plug it off and take the vanes out of the air pump, which turned to be another adventure. Couldnt get the old one apart, did it to a new pump cause I still need it as an idler. We figured that removing the air pump could only effect the O2 sensor and that isnt even for sure. We will see.
 
  #13  
Old 02-15-03, 07:37 AM
NutAndBoltKing
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Tough luck ..

... on soldering that piece. Hindsight is 20/20 but I don't think that it would have withstood the 900 degree operating temperature you mentioned. Nearly all the soldering and brazing materials I've come in contact with had 600 to 1000 degree melting temps.

I wish my blacksmithing Grandfather was still alive to answer your original question. He did repairs on pressurized stainless steel tubing, mostly for maritime use, and depending on the use for the piece and on the materials it was made from he would weld or braze it together.

It seemed to me that each material required it's own type of brazing rod and preperation. He had all kinds of rods and spools. Some for stainess, copper, brass, and some for combinations of those materials. Some were 10% nickel or lead, some were 15% and so on. Some materials needed to be claned with acid and then neutralized before brazing, others had to be dipped in ketone first.

I'm sure brazing materials have come a long way since then and can withstand higher heat and pressure; but it seemed to me that prepartaion and choosing the right brazing rods were the keys in my Grandfather's time and are still keys today.

The shipyards used to send him work, or the ship's engineer would bring it in to the shop. (Everything was a rush). Sometimes he'd fire up his chain drive Mack and go to the dock. I remember one summer he did repairs on pump fittings for a Holland-American Line trans-atlantic cruise ship. He had to braze threaded brass fittings onto stainless tubing for new low pressure fire standpipe connections, and then weld new threaded fittings on high pressure steam lines for the heating system.

Even with my help (ha ha) he wasn't able to finish up before the ship had to leave port - so we went with it, and then a tug brought us back to Hoboken when we were done.
 
  #14  
Old 02-15-03, 09:39 AM
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Hi there nut and bolt king, I sure wish I would have been able to have someone like your grandfather to teach me, In my case I had an uncle in northern MI that ownes a nusery and when I was about 14 years old he told me he hired a welder to come in and do some welding on a boiler and that the guy charged $35.00 an hr. mind you this was back in 1981'ish I thought great if I did this I would only have to work 2 hrs a day and I could make more than anyone else that had an 8 hr a day job.
Boy was I ever wrong, I didd'nt have a clue as to what over head was all about, I worked in a welding shop as an apprentice for about 3 months for $3.35 an hr. and had to quit that job. after that I bought a beat up portable welding truck with a welder on it for $1,100.00 bucks and called myself a portable welder, and boy did I ever mess a bunch of stuff up, well when you have to pay for your mistakes you sure do learn awfull quick what you can do and what you cant do. The up side to my story is I dont have a BOSS accept for my wife and my 500 customers the down side is I never had any one to teach me the right way to doit and I always seemed to find the hard way of doing it, untill I've done it once.
And by the way nut and bolt king, I would love to have that chain drive mack you mentioned, I went to an old truck show at GREEN FIELD VILLAGE in Dearborn MI. about 5 years back and seen a chain drive and thought it was killer.
 
  #15  
Old 02-15-03, 12:01 PM
NutAndBoltKing
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Talking That Mack really was no fun ....

.... because the windshield was missing and we got bugs in our teeth driving on the highway. We had to go up steep hills in reverse because the engine got gas by gravity. Stopping was a real adventure especially when the beast was loaded down with stringers and lintels. Fred Flintstone had better brakes.

My Grandfather had three signs in his shop:

$15 per hour labor
$20 per hour if you watch
$25 per hour if you ask questions
$30 per hour if you help

Not responsible for horses left outside.

I don't tell you how to dig ditches so don't tell me how to weld.
 
  #16  
Old 02-15-03, 03:03 PM
S
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My bud has one in his garage, "We dont lend money and the bank dont do valve jobs"
 
  #17  
Old 02-16-03, 04:19 PM
scrapiron
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Man, I love the stories about the early welders and blacksmiths. There's a picture of an early portable rig similar to the one mentioned on page 1.1-3 of the Lincoln welding handbook.
A motorcycle shop I used to frequent had a sign that read:
Labor- 25$ per hour, 50$ if you worked on it first.
 
  #18  
Old 02-17-03, 10:56 AM
Portable Welder
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Speaking of Greenfield Village to nut bolt king, There is nothing I love more than to go to these festivals, shows, museums and watch the guys that do the Black smithing and the ferriors shoeing horses. My wife gets madd because all I want to do is stay in the shop and watch. Do any of you guys know of any good ones to go see, where its not a 19 year old kid trying to teach me. I would love to have a chain drive Mack with a portable back smith shop on it to haul around to different events.
A MAN CAN DREAM CANT HE.
Funny sayings: On my refrigerator here in my shop I had a sign painter draw a Micky Mouse character on it with the saying ( IF YOU WANT IT MICKY MOUSED HAVE MICKY DOIT) This always gets a lauph from my customers.
I used to have a sign that said I can weld any thing but a Wise crack, the crack of dawn, or a broken heart.
 
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