Ask your WELDING questions here.

yes all NASCAR chassis are MIG welded. When you smash them at the rate they do you have to. But there is a lot of TIG work in those shops as well. But in the off road world and rally and everything else but roundly round racing its TIG welding for the most part because of its streith (when done properly) and the fact that most chassis are made of 4130 which is not a fan of MIG welding. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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the "Sic Bro weave" made me LOL because i have seen my fair share of that as well. Everyone in so-cal with a flat billed hat and a tube bender is a fucking car builder bro!<o></o>

All processes can pass a bend or xray test when done properly. Matching the process with the job is a different thing.

Sent from the phone in my shoe. Maxwell Smart.

I was thinking of cutting a gas tank open. Repairing the pin holes and inserting a wedge shape piece of metal to the tank to increase the capacity
Good welder Miller 211 mit. Noob welder who has a ironworker friend who will help me

Can this be done?

This is exactly my point, MIG welding is more than strong enough on cages that can take the bashing NASCRAP doles out. The quality of the workmanship is more important than if it is TIG or MIG.

Of course it can be done, the question is do you or your friend have the skills to do it right and not make a fugly mess?

I refuse to weld gas tanks any more. Its not worth the risk to me.
Do as you wish. Have the tank steam cleaned out by a radiator shop before cutting it open. Purge the tank with Co2 or welding gas.

Look closely at the pin holes. The area is usually bigger than you think. This can be repaired with a good two part epoxy like 3M Structural adhesive available from Napa and other places.

Can you put .023 wire in the Miller 211? Do you have C/25? Can you weld thin sheet?

Good luck, Take pictures

David

Bolt was sticking out of the head. I weled a nut to it but the bolt broke off again in the head



SO I welded a tit to it.



and a nut to the tit




I did a bunch.



Miller Passport .030 wire. 280 ipm about 130 amps

Just about to deploy the new TIG on some 4130 tube for the 1st time. Making a simple soft pannier rack for a friend's XT250 out of 5/8 dia .065 wall tube. The design should be plenty strong even if my welds aren't 100% but it's always nice to do stuff right. I will practice a bunch before starting on the job. I've built a couple of similar racks that have worked well but have had a mate do the actual tube welding as we didn't have the gear then.

The key joints will be where the tube is butted against the mild steel bushes I have machined up for mounting points. Will common garden ER70S-2 filler do the job ok? Post heat to cherry red with the torch for max awesomeness? Any other tips for the tube welding n00b?

Cheers
Clint

Ok i'm asking

ER70S-2 will work just fine, Just take your time and do a nice job.
No need for all the post weld drama...just weld it up nice and you're done.

Opinions Vary...I don't know all the fancy text book stuff, but I have a few years of actual hands on TIG exp.

Good points. Here's the head tube lug jigged and heat-sinked prior to brazing - inserted rather than butted in order to get a better mechanical joint with some overlap. The brass flowed nicely into the joint - so much so that I needed to chuck the thing into the lathe afterward and clean up the ID with a boring bar.



And here's the head tube with the finished lugs silver brazed into place -



The homemade lugs join the sloping top tube to the (steering) head tube and the seat tube using silver brazing (56% cad free). The sloping top tube is mitered on both ends and butts against the head tube and seat tube inside the lugs. Since the top tube is under compression and the ends butt solidly against the head and seat tubes I'm thinkin' that I'm OK - the lugs aren't carrying much of any sort of load.

The bottom (lower sloping) tube is under tension, but that's silver brazed into an American-made investment cast lug at the head tube and into an American-made investment cast bottom bracket (where the pedals go).

But to your point, at least one builder that I know of who uses brass fillet brazing instead of lugs has experienced a failure of the junction between the head tube and the down tube on a bike that got used hard - a mountain bike. Fortunately I wasn't involved.

That is quite a good explanation of the art of 4130 welding! That whole undercarriage was built out of 4130H? <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

Good explanation - one of the reasons that some bicycle builders stay away from TIG welding chromo frames. But here's a welding / motorcycle frame question for you: Lots of us own a Honda XR650L, and some of the owners have experienced subframe breaking. The more skilled among us (read that as "not me") have welded in gussets to fix or prevent the notorious subframe breaking. For example:

I'm guessing that the Honda frame is some sort of "high tensile" steel. If it were chromo you know that the advertising guys would be making a big deal out of it. If it's not 4130 how would you recommend sticking gussets in place? TIG? Something else? Any approach that you'd avoid like the plague?

Thank you, I learned. :)

David

Sent from the phone in my shoe. Maxwell Smart.

Thank you too!

Those frames are probably plain carbon steel, so the welding method is fairly unimportant. In general TIG gives the best weld quality, but the skill of the welder is number 1, period. A real good MIG weld on mild steel is far better than a crummy TIG weld.

My lucky rabbits foot works..or perhaps it is more than just luck...



4130/ER70S-2 / TIG

Benesesso, thank you very much for taking the time to write that up. I learn something new every time I visit the garage forum.

I'm sitting here with "How it's Made" running in the background. They are tempering shovels in an oven while I am trying to glean some knowledge from your post. Pretty awesome!

No wonder I can't stay off this site. I might even have to print that out and hang it on the garage 'fridge!

Holy cow, You were on Elmer's crew? My hat is off to you. Never met him, but wanted to.

What are you doing now?

I was taught to make another pass when welding hardened steel and cast iron to add heat and slow cooling.

This helps prove why trigger mig welding or consecutive tacks is a poor method.

David

Sent from the phone in my shoe. Maxwell Smart.