BUBBLE GUM WELDS can they fixed

Old 11-09-2012, 10:40 AM
  #21  
curtisreed
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Default Re: bad welds

Originally Posted by outlaw256
Originally Posted by curtisreed
I have done quite a bit of TIG welding so here is my opinion on a couple of things asked here.

Originally Posted by todd8525
Not sure but i was told u are not suppose to TIG over a MIG weld?Yes /No or is this a myth.
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.

Originally Posted by outlaw256
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...
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
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.
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
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Old 11-10-2012, 04:32 AM
  #22  
outlaw256
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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...
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Old 11-10-2012, 09:46 PM
  #23  
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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.
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Old 11-11-2012, 02:49 AM
  #24  
outlaw256
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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 !!
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Old 11-11-2012, 05:48 AM
  #25  
zipper06
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Originally Posted by outlaw256
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.

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Old 11-11-2012, 09:26 AM
  #26  
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AAAAHHH... GREAT info, Zip ! Man would i ever like to take a tour through your work place ! I'm always fascinated about manufacturing processes and the peripheral skills supporting them.
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Old 11-11-2012, 09:41 AM
  #27  
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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.
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Old 12-29-2012, 05:11 PM
  #28  
keithdyer
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Default 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
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Old 12-30-2012, 08:22 AM
  #29  
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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!
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Old 12-30-2012, 09:48 AM
  #30  
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Default Re: Weld Penetration

Originally Posted by keithdyer
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
MMMmmm... So all those tens of thousands of race cars cages built all over the world and many have held together in horrendous wrecks, that were mild steel and mig welded are a figment of our imagination ? Mine have kept me alive and intact a few times with ZERO failure points..
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