Tips for welding underneath a car?

[tomfc]

Well when welding normally i can get a nice strong weld going, but when i do to weld underneath a car, the weld just doesnt seem to want to work.

When i go to make the ark it arks, but doesnt stick to the metal it comes back down the wire or if i crank the power and wire speed right up, it just hits the metal builds up a big pool and then the whole thing falls of.

Iv cleaned up the metal properly and even tried on a different car on the underside but the same thing happens.

When i try to do this is get the nice fizzing ark sound that you get when laying down a nice weld, but it just doesnt stick to the metal, just builds up a big ball of molten metal that sits on top of the metal, but when working from the top it last down a lovely strong weld (cant break the weld with a 10lb sledge hammer, when its clamped between two vices... but does break my work bench )

I can get it to ark sometimes, but only really for a spot weld and thats if im really lucky.

just seems a bit weird to me how i can weld well when above the metal, but as soon as i go underneath it doesnt want to play...

Any advice would be great.

Initially i though it might be a dodgy earth, so i welded the earth clamp to the car, but the same problem, but above the car it would weld lovely.

Im using a 180A mig with Argon/CO2 mix...

 

[zzr1200]

Sounds like the filler wire is being trapped in the torch liner, try straightening out the torch lead as much as possible.

If your machine, was a s/hand purchase have you replaced the torch liner?

 

[NTwoO]

Tip 1 is to build and let cool. Repeat that. If you just go ahead and fire away, then it all gets too hot. Try taking a plastic tub with ice in it (not blocks, but a solid piece). Turning it upside down, the ice stays. If you now heat it up, the molten ice runs out. Metal will do the same, but most metals are more viscous. This means just after melting it and adding some material, you can let it cool and it will stay.

Tip 2 is to get yourself a decent leather jacket. Don't take chances with overhead welding! I had a huge dollop fall onto me. It burnt me a 1" disk in my armpit. After a week I got a bacterial blood infection and spent 17 hours a day for 3 days sleeping. Really, believe me! It is very dangerous to weld overhead without decent protection. If you can't afford a leather jacket, make yourself a biff from an old leather couch dug out at the dump. Make sure your arm and chest/stomach is covered.

And of course, for you guys that understand Afrikaans, Lipstiek Dipstiek (an Afrikaans movie) has an example that it can get even worse.

 

[zardoz]

Can you get any pics of this poor upsidede down welding ? This happened to me too, though not quite as bad. Never found out why it was, like you i can weld perfectly well from above. It certainly wasnt my machine as i own a Portamig.

NTwoO, OUCH! that sounds terrible, i hope i always remember to wear my fireproof overalls and my leather apron when welding overhead. what happens in the movie you mention ?

 

[NTwoO]

It is an SA comedy. Reasonably early in the film, the hero burns his family jewels with the arc welder while he is distracted by a beautiful girl passing by. The scene is filled with hilarity.

 

[chunkolini]

Tom, try practicing inverted welding on pieces of scrap, then you are working inverted without the added distractions of being under a vehicle. You can try variations and see what you are doing. I can remember it was impossible to weld verticaly or upside down. Now i can do both and cant see what the problems were. I can remember getting realy excited when I did my first upside weld weld.

Note, dont do it wearing a nylon ra ra skirt.
A very cute neighbour was welding under her truck dressed like this. The screams when she set her skirt on fire had all us blokes in hysterics. I saw some of the scars, but did not pry too far.

Chunko'.

 

[martinez]

any pictures of the neighbour ?

 

[pedrobedro]

Turn it down and slow the wire down a bit works for me when I'm under the car and I steepen the angle of the tip to the metal so I don't fill the shroud with crap.

 

[Antsuno2]

dont try and get a long run, do series of small zips, make sure the edges are very clean as are coated with zinc and waxoil seeping through, Ant!

 

[Iain Westland]

short bits and cleaner than clean. dont rush. protect your self and make sure your comfortable.

also make sure that both the car and the patch are always in contact, sounds obvious but its very easy to get a 1mm gap between them that your trying to pool so keep tapping with a hammer to close the gap

Iain