BUBBLE GUM WELDS can they fixed
 

I looking at buying a drag car the welds look like they were globbed on.
the rest of thecar is premo. so the question is can a bad weld job be redone if so how much would a shop charge to do this

Re: BUBBLE GUM WELDS can they fixed
 

ive seen a few like that.... lol they ground down most of the weld and laid bead with the mig right over it... as long as you get it hot enough to get good penetration... it will be fine :wink:

thx for the input if I decide to get it i'll be looking for a good welder in north fl.

i hear ya! their was a guy at our track a few years back that built his whole cage out of pvc tubing and used silicone to make the joints look like they were welded and then painted it all black...... just to save weight... the dipshit was running in the lower 8's too..... :shock:

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i hear ya! their was a guy at our track a few years back that built his whole cage out of pvc tubing and used silicone to make the joints look like they were welded and then painted it all black...... just to save weight... the dipshit was running in the lower 8's too..... :shock:[/quote]

I have heard of exhaust tubing, but never PVC. Thats what the Darwin awards are for...

he was regular.. there every week guy. he "built" the new car and bob"the owner" just assumed it was done like the rest of his cars and let him run... he ran it for a few months before someone blew him in.... :o

bad welds
 

Not sure but i was told u are not suppose to TIG over a MIG weld?Yes /No or is this a myth.

I know very little about TIG welding.I bought an aftermarket rear sus.for my truck.the truck is on a jig and the rear sus.has been tacked with MIG.The finish welding will be TIG, by a pro. Have i done more harm than good,by tack welding in MIG.

cool thanks.

dont have a tig welder here but i gotta hell of a big mig. we have built frames amd everything else you can think of. why is tig now the only way to go when mig was it before. someone with a gun in his hand that knows how to weld can weld a frame up just as good and strong as tig welded.imho...

Re: bad welds
 

I have done quite a bit of TIG welding so here is my opinion on a couple of things asked here.

I believe the issue would be if the whole thing were MIG welded and then ground down / or not, then TIG welded over because the TIG is such a smaller weld bead that you would not get weld penetration to the base metal only into the weld already there.

I think because moly tubing is so much more prevalent than in the old days. Tig does provide a smaller nicer looking weld in the right hands and MIG is not recommended on moly even though it can be done. It is a little harder to tell the penetration of a MIG weld also.

Curtis

10-4 on the moly and mig, unless you for sure know what you are doing, i would stay away from any high stress areas, with mig welding and moly tubeing.

Could be either, but you weren't wrong. It can be tacked with MIG and finished with a TIG.

Curtis

i myself fixing the bubble gum-use a mig.I was asking a different question.sorry.Now im not a pro.but decent with a MIG.Watching pros. on TV and such i seem to see them MIG the frames then TIG the cage.I'm a collision repair tech and fix wrecks all day long.But welding a full frame or a cage no.I'll leave that to the pros.I stand behind my repairs.but don't feel comfortable roll testing a cage that i welded.
I'm building a 98 gm regular cab with a 10 foot box dually,twin roots blowers from a 3.8 liter 6.6 duramax.The rear sus is a 4 link bag kit.I'd rather ask guys who do this all the time rather than the smuck at the local donut shop.Thanks again fellas.

Re: bad welds
 

well curtis thats a good answer. and you are right about that. but ive built frames and for hotrods and racecars with my mig and we have them all stand strong for yrs. i made a roll cage back in the mid 80s that got a true test in a 57 chevy ,buddy rolled his streetracer at 100 mph and walked away with a hell of a headache but he walked away. yeah tig is pretty but is it really stronger. that doesnt make any sense for it to be stronger if you really break it down.

Re: bad welds
 

I don't think the strength of either is in question. Both will hold until the base metal tears. I should have qualified what I was saying by adding that the TIG is mandated on Moly by the HRAs. They certify the cages and you can tell a good TIG weld from a bad one easier than you can a good or bad MIG weld. I'm just talking Moly here. I am only so so with a MIG gun in my hand but I know guys who I would trust my life with to MIG a cage for me on Moly tubing. I, on the other hand, only trust myself to TIG Moly.

You are absolutely right about the strength of MIG welds being safe though.

Curtis

thanks man now i feel alot better. ive been told that tig was stronger and all this other bs.never could understand how it could be stronger welding is welding PERIOD.as long as you can penatrate the metal and pool it together its there.now im going out a roll a car, going to retest my welding...lol not really am already crippled up...

The reason that Tig welding is mandated on Cromoly, is that it doesn't cause embritment at the adjoining surface of the weld. Both stick and mig welding causes the metal close to the weld too get harder and fractures easier on any 4300 series steel. We do lot's of welding in the Plastic injection mold building business and we have everything from mig to laser welding equipment. We weld on repairing molds from every thing from 4340 mat'l to tool steel. Most Molds are built using 4340 mat'l and heat treated to 42/45 Rockwell hardness, same like rearend gears, except the pro gears which uses 9310 mat'l, which is the same except has more nickel mat'l in it.
The mig weld is absolutly as strong as tig, but it causes the embritment on cromoly. The mild steel chassis or roll cages do not have the embritment factor that cromoly doe's.
I can assure that every inch of weld on my roll cage in my Malibu is tig welded, because it's cromoly and it's only a 6.50 car in the 1/8 mi.

Zip.

thanks big time zip!!! im runnin a copy of your post off and going to hang it in the shop and dare anyone to argue with my hero!!!lol i was at one time a certifed welder,like back in the late 70s.lol long time ago i know. thats the answer i wanted right there.im not up on the material aspect as i should be. but i will be !!

Outlaw i should have added 4100 series cromoly to the list since that's what most roll cages are built with. Even with the cromoly mat'l that we use in racing, we don't use the very best cromoly. There's about 10 different mIL specs for cromoly for the aircraft industry, and the automotive industry uses the cheapest grade, except some crankshaft makers like Wienburg, who's cranks cost around $4,000.00 VS the ones that we buy for $400.00 to $600.00.

Zip.

We have one of the best equipped shops in the South, with between 3 and 4 mil. in CNC equipment 4 and 5 axis milling machines CNC lathes, wire burners and elox machines. We can punch a 1/16" hole thru an 8" pice of 60 rockwell steel in less than 10 min. and it will straight within .002 at the exit point. We don't work in thousands we work in tenths of .001. We do a lot of work for the medical industry and repair broken molds that some times weigh as much as 5,000 when they are all together. We're small only 12 employees but precise, and everything is CNC.

Zip.

Weld Penetration
 

Like Curtis said ^^^^^ "It is a little harder to tell the penetration of a MIG weld also".

Uhhhhhh . . . . , I would NEVER trust a shallow penetration MIG weld on any Suspension or Roll Cage weld, PERIOD.

Let the T-shirt welder guys on TV use it on sheet metal, should not get anybody very hurt.

I still have several clients that will not allow MIG welding on any of their pressure vessels due to this very fact.

44 years of this stuff.

Take care, K

Off the subject, but Zip mentioned Winburg Crankshafts. If you have ever held one in your hands you will agree with me that they are a stunning piece of art. It's almost a sin to hide one inside an oil pan! :)

Re: Weld Penetration
 

Re: Weld Penetration
 

So all those thousands of race car cages have shallow welds? I think this was pointed toward the original question of bubble gum welds and not being able to tell the penetration of it. Not a one is better than the other comment. Don't jump down someones throat to fast.

Curtis