begginers weld problems with OA

The other day I was doing some practice on an old wreck of a car by cutting a square out of a panel then trying to butt weld a new piace in.
With the goggles on everything seemed OK, the puddle formed fine and the 2 pieces seemed to flow together fine, I thought my speed must be fine too as if I slowed down any I would blow a hole clean through both pieces (so I'm thinking it must be penetrating fine too)! I dip the filler rod in as and when required (which wasn't all that often along the top run. However after getting the top and bottom runs completed I saw that the top run ( requiring a minimum of filler still looked like 2 seperate pieces of metal and on grabbing with a pair of pliers and pulling just cracked apart, so there goes the idea of decent penetration. The bottom run (requiring more filler) was no better and the filler material had cracks all the way through it and most of the filler just cracked apart and flew off when given the attentions of a hammer.
The car is just plain sheet steel and using ordinary steel (not stainless) filler rods (when buying the rods I told the guy what they were for and he gave me these rods, he's infinitlely more knowledgable on these matters than I :=) ) Any pointers greatly appreciated Thanks Jim
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"Jim" delete: (clip) the puddle formed fine and the 2 pieces seemed to flow together fine, (clip) ^^^^^^^^^^^^^^^ From your description, it sounds like the weld should have been too strong to just break apart. I suspect the rod might not have been steel--possibly brazing rod. (The salesman could have made a mistake. I recently had the OWNER of a welding supply hand me a roll of aluminum MIG wire when I was asking for stainless.) The alloy of brass and steel is very brittle. Hold the rod against a grinder and see whether you get sparks. Try a weld with some coat hanger wire and see whether you do better.
Aside: I wouldn't waste more of the car on this until you get it solved. Go to a body shop or wrecker and get a body panel to play with at the bench.
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Leo Lichtman wrote:

I've tried the grinder on the rods (I have a couple of packs of different diameters) and they all spark up fine. I'll give the coathangers a go later as soon as missus isn't looking :-)

The car is fit for scrap anyway and I'm just using it for practice antil it goes to the wreckers. I thought it would be the next stage up from some 'clean metal' on the bench and give me a better idea of 'real world' welding.
I'll pop and see an autobody guy I know and see if he can suggest some different rods, then go back to the bench with those.
Thanks Leo
Jim
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If your flame was not neutral you could have oxidized the weld or added carbon making it brittle. Sheet metal on modern cars is better than the mild steel bodies of yesteryear. The alloys in modern bodywork demand wire feed welding or TIG for proper repair. Your problem could have been one of those suggested. Try some simple weld beads run on the surface of the metal first. Randy
The other day I was doing some practice on an old wreck of a car by cutting a square out of a panel then trying to butt weld a new piace in. With the goggles on everything seemed OK, the puddle formed fine and the 2 pieces seemed to flow together fine, I thought my speed must be fine too as if I slowed down any I would blow a hole clean through both pieces (so I'm thinking it must be penetrating fine too)! snip Any pointers greatly appreciated Thanks Jim
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R. Zimmerman wrote:

The car's from 1980 (it's an old wreck of a mini) and reknowned for their poor quality mild steel, I'm welding mild steel sheet into the parts I've cut out and the rod packs say they're mild steel too. Having said that I have managed to succesfully weld the 2 parts together with my MIG. Trying to run a bead on a piece of old panel goes OK, the only difference being the panel is inside, the car's outside and it is a bit windy out there ! I'll play about with the flame going from slightly carbourizing to slightly oxidizing and see if that makes any difference.
Thanks for the suggestions Randy
Cheers Jim
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R. Zimmerman wrote:

Problem sorted ! A dodgy acetylene regulator it appears. Just after setting the flame the acetylene regulator 'relaxed' a bit thus as you were saying, I was getting too much oxygen into the weld. The solution ?? A nice brand new set of multistage regulators :-) You really do get what you pay for here and as I'm mostly messing about with thing guage steel I can justify the extra cash (plus I got just over 20% off )
Thanks for the advice
Jim
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