I've been practicing my welding (flux core) on a few scraps of about 1/8th inch stainless I've had laying around, and am getting some nice looking results (minimal splatter, good penetration), however when I attempt to weld my mild steel pipes together, my flux core gets greedy and eats holes in the metal. Any idea WTF I'm doing wrong? I have a friend with a MIG and shielding gas I could use, but I need more pipe

 

Are you trying to use the same voltage and feed rate you did with the stainless?


Kinda weird you were able to get good welds on stainless with the flux core. But what do I know, I'm a rookie with welding.

 

Never flux cored, so keep that in mind. I have ~60 hours of stick welding. In my experience the work (.060 steel tubing) has to be spotlessly clean to get a good weld. The pipes I bought were aluminized. I had to grind that off 100% cause it ruined the weld. If I tried to weld the puddle would just run off or burn through.

I'd run over the pipes where I was gonna weld with a die grinder to get it to "clean" shiny metal, then square the edges back so I have a good amount of metal to weld to (so it's not thinner and easier to melt through). Put the tubing together and clamp the work. Clean area to weld with acetone. Now it's clean and ready to weld.

 

I just welded for the first time on saturday, harbor freight 90a wire - I welded through just like you, when i was lingering too long on the same spot. keep it moving.

 

welder is turned up too high. lower the amps and wire speed

 

In addition, work the trigger in short bursts rather than a continuous feed. By short, I'm talking maybe 1/2 second. Experiment until you find a point that gives you adequate penetration without blowing holes in the material.

 

yeah on the stainless I let it sit for a second to sort of create a pool, then I act as if I'm trying to push the pool of "molten magma" with the tip of the torch. I have already got my power low, I still need to experiment with intermittent wire feeding and various lower wire speeds

 

If you haven't already go to your local library and get a few books on welding. I did this and it makes the learning process a lot more efficient. Rather than fail at something and struggle you'll know what's happening and be able to correct for it. I've read 5 books on arc welding and a couple general welding books. Really helps a lot. Now I can be welding and know what it's doing, and vary arc length, weave pattern, drag, speed, etc to get a good weld.

 

thin pipes are very different from 1/8" plate.

wire feed has a big effect on burning holes too. you want it fast enough to fill the weld in, but slow enough that it doesn't poke through into the pipe. too slow and it wont maintain an arc. for pipes, I like to use a little faster feed.

Critical also is chamfering the pipe at the joint. and you want a TIGHT JOINT. no gaps. gaps will burn away into holes. and forget filling holes.

you can also use low power and do a few passes instead of one hot pass.

 

thanks for the help guys, I'm going to go weld the **** out of every piece of tubing in my garage on Thursday morning whether it likes it or not I just recently have been doing a tad bit of reading on flux core, and have already learned tons of information to help me do good on the 1/8" plate, just need to read some more in depth material.

 

When I did thin wall tubing the trick was high heat and very fast feed. Preheating would have helped with this technique. If I went slow with low heat I'd go a couple inches and then burn a hole no matter how hard I tried not too. It seemed inevitable. So instead I'd turn the heat up and just go to town with it. Strike an arc, make a tiny puddle for like .3 seconds, then bury feed and drag to get a decent root pass. Once you get the root pass, a cap is easy and your 10x less likely to burn a hole. Like Y8s said, fixing holes sucks. I was using 3/16 7018's welding .060 tubing. Damn near impossible to fix holes.

 

you can also back the tip away from your work....sounds stupid but it will "cool" off the temp a bit and let you weld little slower and with slightly longer trigger pulls....careful though cause if you pull back too far the wire will dance around and make a mess.

 

While this works ok for flux wire, you don't want to pull back much with a gas fed MIG or your shielding gas tends to blow away and give you horrible spattery welds.

 

fickin zombie threads today