Nagging issue

[cheapracer]

Hi Guys and thanks for taking a peek!

I am a self taught welder over 30 years, excellent ARC, fair to middling MIG.

I have a 250 MIG and have a nagging problem I can't seem to resolve - I can't get a flat weld, always I have a hill in the middle (for want of a better word) and I mean a big ugly hill on each run.

I have tried every setting combination from min/max volts and min/max wire etc. The machine uses 0.8mm wire and has a switch for 0.8 and 1.0 and I have tried every combination and I'm talking over a period of months.

I generally weld mild steel around 2.0mm thick at many different intersecting angles and verticles etc. - actually the verticles look like the others should look like.

It's like it's feeding too much wire all the time but of course I slow that down and then it burns the wire off too quickly, so I turn the volts down and then it doesn't have the heat blah, blah......

I have been using a gas mix of Argon and CO2 because I was told it produced a nicer looking weld which I believe it does even at twice the price. I also use a low gas speed/volume simply by turning it down until it had an effect then turning it back up a little.

There is also a wire tensioner/roller inside the machine, I have played with the settings but can't seem to appreciate any difference.

Any tips would be great

Mark :-)

 

[shenion]

Some pics may help.

I find a steeper torch angle (closer to perpendicular) helps flatten the weld as does a push travel.

What gas mix are you using?

 

[cheapracer]

Some pics may help.

I find a steeper torch angle (closer to perpendicular) helps flatten the weld as does a push travel.

What gas mix are you using?

Thanks Shenion.

I have been using the MIG for over a year but ARCing since I was a Teen so I will try the angle thing as it may be a habit from ARCing as is pull travel.

It's supposed to be/I order 80% Ar / 20% Co2 - I did note on the last bottle that it said Co2/Ar rather than the previous labeling of Ar/Co2, I don't know if that makes a difference or not.

Will post some pics Monday

 

[cheapracer]

Hey Shenion, I got this from your web info page, sounds like my situation especially the arc being very loud with a distinct "crackle".

Penetration does not really change much. There is a bit more penetration with higher CO2 mixes. The main difference is the width. High Argon mixes cool the weld pool and it "beads up."

100% Argon just produces tall welds. Arc is loud and blue. You can hear if the wire speed is wrong

Maybe I'll try a bottle of Co2 on Monday to compare. Problem in China is you can't trust what they give you (I'm Ozzie by the way).