TIG welding cages

[chknkatsu]

For people who actually know how to TIG weld.

Depending on who you ask, and what kind of builds they are used to everyone has an opinion on how cages should be TIG'd. Some argue that 2 passes is a must, some say it's dumb.

pictures are from my cage on my old jeep/buggy. One pass on .120 DOM. (not a professional welder)

*trend I've noticed is that MIG welders always seem to think these are underfilled

For arguments sake, we will use .120 wall as a base line for discussion.

 

[Provience]

from the pictures, those welds are just fine. they are underfilled if you can see undercut on either side, so add more if that happens, or if you have a depression in the middle of your weld, in that case add more.

especially 0.120, a single pass is plenty


2 passes is a must is dumb

gotta be all straw is also dumb

pile it up like a mig is dumb

gotta have a weave cover pass is dumb


UNLESS you are making money selling pictures on instagram, if you are doing that, then do whatever sells you the most product

 

[Eric]

^ What he said.

You are good.

 

[thedirtman]

Top one looks a little undercut but the bottom one looks fine.

 

[tracyb]

when it comes to cages what i see is;

most mig is too cold and most tig is too hot. and picture dont tell the full story.



bottom line is... its not the process or the procedure, its the welder.


if anybody is insistant on one over the other, or two pass vs 1 pass... they are fucking retarded amateurs.



**also, i'm a self employed welder/ fab person. i've never tigged a cage in a personal rig, only customers.
***also,also. chromo is a different story, and i dont fuck with it. if dom is good enough for nascar, its good enough for anyone that wants work done at my shop.

 

[AgitatedPancake]

I personally think it's very common to see TIG welds in the automotive industry that are concave and seriously underfilled. The way I look at it, If I cut a cross section view of any two parts I weld, I want to see the wall thickness of the filled area to never dip thinner than the wall thickness of the thinnest part being welded no matter what process is used. Far too often do I see people proud of "small" tig welds with two peices of .120 wall tube being connected by .065" of filler depth. Saying "the weld material is stronger than the base material" is no excuse there imo.

So as long as you feel like your

 

[Provience]

I personally think it's very common to see TIG welds in the automotive industry that are concave and seriously underfilled. The way I look at it, If I cut a cross section view of any two parts I weld, I want to see the wall thickness of the filled area to never dip thinner than the wall thickness of the thinnest part being welded no matter what process is used. Far too often do I see people proud of "small" tig welds with two peices of .120 wall tube being connected by .065" of filler depth. Saying "the weld material is stronger than the base material" is no excuse there imo.

So as long as you feel like your

agree. fully.

i'll even throw another example, because pictures and more stuff to critique

Not a roll cage, same concept though. this weld as a single pass was nowhere near what i wanted

so rather than try to make one wide weld, laid down that width all the way around and then made a second pass. close enough that it was easy to weave and cover

 

[bdkw1]

Single pass is fine for .120 wall if done right. That steering cylinder is much thicker and can benefit from double pass.

 

[HYDRODYNAMIC]

I’ve heard single pass below.120 and double pass over .120
So .120 is teeter tottering. If the fit up is tight enough use a single. If it’s loose then fill the gap, let it cool a little and do a cover. This is better than under filled or over cooked trying to melt all the filler rod across a wide gap.

Rod size plays a big part in how much filler you can put down and how hot it needs to be to get it to flow.

A big plus for TIG is 100% penetration without having to run too hot or add too much filler.

 

[cj3a]

Weld some up and cut and etch. It is a eye opener

 

[chknkatsu]

agree. fully.

i'll even throw another example, because pictures and more stuff to critique

Not a roll cage, same concept though. this weld as a single pass was nowhere near what i wanted




so rather than try to make one wide weld, laid down that width all the way around and then made a second pass. close enough that it was easy to weave and cover

that cylinder is definitely different than what a cage. I would do two passes as well like i did for my control arms

 

[Provience]

I’ve heard single pass below.120 and double pass over .120
So .120 is teeter tottering. If the fit up is tight enough use a single. If it’s loose then fill the gap, let it cool a little and do a cover. This is better than under filled or over cooked trying to melt all the filler rod across a wide gap.

Rod size plays a big part in how much filler you can put down and how hot it needs to be to get it to flow.

A big plus for TIG is 100% penetration without having to run too hot or add too much filler.

Rule of Thumb: 1amp gets 1thou of thickness

120 amp = 0.120" full penetration weld

3/16"=190 amp

and i think that is where the over/under 0.120 you've heard of comes from. 115v machine or using 115v is not ever going to get you 190 amp and i'd wager that MOST people welding in their garage are using ~200amp machines at max (yes, i know several people have bigger rigs, but they aren't the majority by any means).

.120 to .120 wall tube all day long, single pass with a good fitup.

.188 to .120 wall tube, i try to keep my heat mostly on the thicker tube and go a bit slower to help it out. depending on how it felt or looked while welding regarding throat and undercut and such would determine what happens next

just about everything else gets a gap and that pretty well always means multiple passes.

 

[1Sinner]

Welds look fine. Coming from a guy that is certified in multiple disciplines on everything from structural to aircraft. If you're worried about the joint, or as said before, underfilled, add more filler with another pass. If you're still worried about joint reinforcement, add a gusset. I personally would have back beveled your heim on the steering cylinder a bit, then filled it shoulder to shoulder on the weld. but I don't know how much abuse your rig will see. I've seen crappy welds hold, and good welds fail based on abuse alone.

 

[Provience]

Welds look fine. Coming from a guy that is certified in multiple disciplines on everything from structural to aircraft. If you're worried about the joint, or as said before, underfilled, add more filler with another pass. If you're still worried about joint reinforcement, add a gusset. I personally would have back beveled your heim on the steering cylinder a bit, then filled it shoulder to shoulder on the weld. but I don't know how much abuse your rig will see. I've seen crappy welds hold, and good welds fail based on abuse alone.

for my cylinder, being mounted with a ball joint at both ends and have a tie rod and two cylinders should mean that it gets exposed to very little "pulling" force even if the tire is getting slammed around, so I'm not particularly concerned about it.

as for cages, absolutely use bracing, gussets and design to deal with high stress areas rather than rely on welds.

 

[Im4yotas]

Overall strength is going to be determined by effective throat of the weld, assuming no weld defects. Basically, you want to match your filler metal strength to the base material strength, and then match your effective throat thickness to your material thickness. So the question of single vs dual pass should really be asked like this: Can I make an acceptable weld with a .120" throat thickness in a single pass, or will it take me 2 passes?

If you measure the leg length of the inside corner of the 90 degree joint, divide it by the square root of 2 (roughly 1.5) and that will give you the theoretical throat thickness. Effective throat then depends on convexity/concavity, penetration, etc.

This is oversimplified, but you can roughly calculate the strength of that weld pretty easily. Multiply the effective throat thickness by the length of the weld (circumference of the tube would work, but actual length following the notch will be a little longer), then multiply that by the filler rod strength.

​​​​​​So a 2" x .120 dom tube, grade 1010 has about a 70,000 psi tensile strength and would be evenly matched to a .120" throat fillet weld using er70 filler, also 70,000 psi tensile. This would give you a weld strength of over 52,000 pounds tensile, which matches the tube. If you don't achieve that .120 throat thickness, do you really want your weld to be weaker than the tube? Also, if you have a higher grade of steel, you will need to adjust your weld size or filler to compensate.

I personally prefer 2 passes. If you crank up the heat and dump more filler in, then you might be fine with just 1. But I'm going for a specific look.

 

[gt1guy]

Fit up is just as important as the weld itself. Leaving the razor thin edges on a tube you just pulled out of the notcher will have you welding on material that's way thinner than the base tube thickness. Even the best looking weld in the world will leave a weak joint.

MIG/TIG, it really doesn't matter. The bottom line is you never want the weld/joint to be thinner than the base metal.

I do think it's easy to underweld a joint with TIG.

 

[Provience]

If you don't achieve that .120 throat thickness, do you really want your weld to be weaker than the tube? Also, if you have a higher grade of steel, you will need to adjust your weld size or filler to compensate.

I personally prefer 2 passes. If you crank up the heat and dump more filler in, then you might be fine with just 1. But I'm going for a specific look.

regarding the weld weaker than tube, that is where design comes in to play. if you are doing a butt weld on an open span it is very important, important enough that personally, I don't make that joint unless i''m using an insert that at very least doubles the thickness of the tube in the weld area.

if you are doing a node joint, then it really doesn't matter as much because the design is going to support the load

as you say, you are going for a specific look. that is perfectly valid but not a requirement

 

[Brad]

Fit up is just as important as the weld itself. Leaving the razor thin edges on a tube you just pulled out of the notcher will have you welding on material that's way thinner than the base tube thickness. Even the best looking weld in the world will leave a weak joint.

MIG/TIG, it really doesn't matter. The bottom line is you never want the weld/joint to be thinner than the base metal.

I do think it's easy to underweld a joint with TIG.

Pointed that part about not prepping tubes to someone on IG who posted something he built and mig welded 2 passes “to fill it in”
pretty sure he blocked me

 

[Im4yotas]

This thread inspired me to do some cut and etch work on a little practice piece I had. This is 1 pass only before adding the 45 degree notched tube, then a 2nd pass on everything left exposed. So in the cutaway, the small 90 degree fillet covered by the other tube is 1 pass and everything else is 2. I can see that it was a little cold and small for my liking in the tightest corners of the joints, which is where I cut it, but when measured out everything is still good. The single pass throat is right about .120 and everything else is .140 to .190

 

[mobil1syn]

pulsed (machine or pumping the pedal) or constant peddle?

 

[1Sinner]

Nice work

 

[Im4yotas]

pulsed (machine or pumping the pedal) or constant peddle?

1st pass constant, 2nd pass foot pulsed.

 

[Provience]

yeah looks like it missed in the root a bit, buuuut....that is why automotive is design heavy and let's you get away with a ton of stuff

second pass on top makes it look like a thousand bucks if you are selling them though :)

 

[Im4yotas]

yeah looks like it missed in the root a bit, buuuut....that is why automotive is design heavy and let's you get away with a ton of stuff

second pass on top makes it look like a thousand bucks if you are selling them though :)

Yah, that one missed the root a bit. It has enough throat to not be an issue, but now I know for sure that I want to use more heat. Like was mentioned on the first page, cut and etch will show a lot. This was my first time doing that. I had 90% of my welds x-ray tested at my last job. That was always cool to see the film a verify things were solid.

 

[Provience]

Yah, that one missed the root a bit. It has enough throat to not be an issue, but now I know for sure that I want to use more heat. Like was mentioned on the first page, cut and etch will show a lot. This was my first time doing that. I had 90% of my welds x-ray tested at my last job. That was always cool to see the film a verify things were solid.

hell i have a harder time "passing" cut and etch than xray

but yeah, if you took those welds pre-cut and put them up against anybody else, they would be panty droppin' it's also why i tell people to not be overly concerned about looks most of the time. dimensions are important, proper heat is important, looks? meh

 

[Brad]

Yah, that one missed the root a bit. It has enough throat to not be an issue, but now I know for sure that I want to use more heat. Like was mentioned on the first page, cut and etch will show a lot. This was my first time doing that. I had 90% of my welds x-ray tested at my last job. That was always cool to see the film a verify things were solid.

Clean x ray film is boring to look at

 

[RunningProblem]

Weld some up and cut and etch. It is a eye opener

This is going to be the best way to find out if single pass is enough.

 

[Bebop]

@lm4yotas, Mind telling us what amp you welded these at ? Thanks

And great TIG work BTW !

 

[Im4yotas]

@lm4yotas, Mind telling us what amp you welded these at ? Thanks

And great TIG work BTW !

It was about 155 amps. I was testing to see what I could get away with without popping my 30 amp 220v breaker. I ended up putting in a 50 amp circuit just for the tig. I should do another test at 175 amps because the first one was too cold in the tightest corners. ​​​​​​

 

[Bebop]

Do you agree with the 10 amp per .010 of thickness rule ?