Mig Tig and roll cages

[prostreetboy]

Andy,

Those are amazing welds...makes me realize how far I have to go, I can't do that flat on a bench. Can you comment on wire size, feeds and voltage?

BTW, I'm building a pro-street '37 Chevy with a 572 BBC. I'll post some pics, it's a fun project when I have time to work on it.

Dave

[dragharley]

Still confused...

OK, I am new to welding, but have been drag racing Harleys for a few years
now, and am building a Nitromethane Pro Dragster Harley (moving up in
class). I have been told by several people who build chassis for these bikes
that they TIG weld 4130 Chr Moly with 4130 rod, however, in these forums, I
see that everyone seems to prefer ER70s or, ER80s (which I cannot find
at ANY of the welding supply shops I've been to here in So Cal, what's
up with that??).

Why the preference for ER70s and ER80s rod for 4130?

My chassis is already built (by one of the top builders), but there are a few
gussets and brackets I will have to weld on it, they will be non-stress
bearing components, but I would like to do everything right anyway.

One good friend of mine says he likes to weld mild steel with 4130 rod,
what is the advantage of this?

Thanks much for the help!!!

[BCarlucci]

Andy,

That's a great job on welding that tubing, i am with envy, i'm still pushing along at tig welding tubing, but it's a pain in the you know what. It's always weld 3/4" then reposition the peice. But anyway those are some nice welds.

BC

[DEA]

Besides the wealth information you will get here.There is also a good article at www.tigdepot.com
I'm sure you remember the T/F legend Elmer Trett.

[T-Bone57]

Andy, I find it interesting that MIG (w/mild steel) is used almost extensively on the NASCAR frames whereas TIG (w/chrome moly) is used from Pro-Stock on up to Top Fuel. Whats going on here?

On another note, my sons and I are looking at a project car for drag racing. http://www.swracecars.com/s_10.asp In talking to S&W Race Cars they said MIG is fine for this project. I'm thinking of having S&W send an extra piece of rollcage tubing so we could practice notching and welding. Not knowing what type of joint is to be used to attach the back half what would you suggest as practice for this weld?

These links might be of help to the drag racers in the forum:
http://www.maritimedragracing.com/id5.htm
http://www.nhra.com/contacts/tech_faq.html

I really appreciated your photos, especially the rollcage close up. I now have a good idea of what the finished weld should look like. I just have to decide whether to go with the 210 or 251. Not sure. The only thing I could tell you is that my youngest is taking HS welding 2nd semester and that we will be building more than one car.

Thanks,
Brad

[Sberry]

This is just an opinion,, but I think one of the biggest reasons TIG is prefered is that it weeds out a lot of the "Jethro" in the backyard with a 100 ft of number 16 extension cord on the 120V wirefeed and a hacksaw and a hammer as fitup tools. A guy that springs for a TIG is likely to be that much more competant and fit way better with less large gaps to just "weld up". As for the 2 machines, for automotive work th 210 is going to likely be all the machine you would need. If you were working on heavier equipment and wanted to run a steady diet of 035 or fluxcored the 251 would be worth the extra $ weight. You can always turn them down but you can only turn them up so far.

[Paul Seaman]

The tig process will provide a weld with the smallest Heat Affected Zone.
The weld strength will be the same if the same filler is used but the HAZ will determine which process will be best by reducing the heat affect on the cromoly strength is gained. In pro classes of drag cars the torque stress is much higher than in most circle track cars the exception is top classes of sprint and latemodels.

Hope this helps clear it up some,

[dyn88]

whats interesting is that you say chromemoly must be tigged. When I worked for moroso(competition engineering) we built a couple of Chrommoly rear end assemblies(ford 9 inch) and all the rear assys were migg welded completely. I do know that a bunch of these rears ended up in nhra cars in several classes. do nhra and nascar have different safety concerns?

[cope]

whats interesting is that you say chromemoly must be tigged. When I worked for moroso(competition engineering) we built a couple of Chrommoly rear end assemblies(ford 9 inch) and all the rear assys were migg welded completely. I do know that a bunch of these rears ended up in nhra cars in several classes. do nhra and nascar have different safety concerns?

The TIG requirement in NHRA refers to roll cages. I don't know what they say about rear end assemblies.

[HAWK]

andy, those are some SWEET WELDS, any hints? are you pulsing? Ect

MAN, IM GREEN W/ ENVY !!!

BRIAN

NOT TAKING ANYTHING AWAY FROM ANDY AND HIS GUYS as he and they do SUPER work. I enjoy watching Andy TIG about as much as my son likes cartoons!

The SCR output of the MM251 yields itself to the nice pattern in the beads like Andy has posted. Why? I don't know. I do know these type beads comes natural out of the MM251 for me. With other power sources I have to expend a bit more effort for the same look.

In a recent post I mentioned not caring for stacked beads. This is not what I am referencing. I meant the wider separated stacked beads. These are tight and rippled. The toes are well washed and you can tell they are "IN THERE"!

So A- are you staying in the top 5???

[Paul Seaman]

I did not say require, I said it would be best from a strength stand point. I personally have welded cromoly with mig using E80s? dont remember the last charactor but remember it was 80,000 tensile strength. I believe the welds are of the same strength but the material being welded in mig will have a greater HAZ and thus will weaken the overall strength of the tubing near the weld, where tig will reduce the HAZ and make the strongest assembly by using the least amount of heat to achieve a given weldment.

Typically the sanctioning body will say what they will and won't allow. As for rear differentials, I have seen them done both ways but for the top classes they often tig all they can, for exactly the reasons mentioned above.

I mig nearly everything I can, but I am much more proficient in mig than tig, or stick. But that is just me, Hawk would probably tig all he could, because he that good at it.

Peace,

[T-Bone57]

Bought a 210 as recommended and it should be in next week. Right now we are rewiring the garage. New box with 100 amp service, more lights and one extra 220 and eight 110 outlets. Had 2 cylinders made up /100% co2/ 75%argon 25% co2. Thought it would good to try both. The frame kit supplier is sending a couple extra lengths of tubing to practice notching and welding before we get started. I will cut and notch the practice tubing at different angles to replicate most of the welds. I still need to make up some type of jig to get in some overhead practice. Any ideas here? All things being equal how long should it take to learn the mig process?

[Sberry]

Depends on how good you want to get with it. With some instruction about 2 years,,, ha

[Paul Seaman]

Mig is the easier of the process until you start talking overhead, atleast for it is. Tubing requires a delicate touch, to prevent burn through. I learned most of my mig knowledge in a class in about 16 weeks. In the real world without an experienced welder looking over your shoulder, lets say be patient and stay tuned. If you want help with technique and critical analysis, get a digital cameraand post the pics. One from walmart $30- $50, yea its cheep but it will work and if you ruin it the investment wasn't much.

BTW, Congrats on the mm210, love mine 2 years and counting.

[T-Bone57]

Thanks guys. I sort of figured I was pushing it with such a complicated project. We have digital camera that does close ups real nice. I have a friend that retired from a local fab shop but he's been ill lately. I'm sure he'll hook me up with someone to help me along if he's not up to it. He also suggested I attend a class. So that's on the to do list as well. I have a handful of other projects lined up. I also build home audio power amps as a hobby. You guys are gonna laugh on this one but I could fit one channel in each side of a pair of five gallon Harley fatbob tanks... To be honest I can hardly wait to get started!