Question about MIG wire thickness

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This is probably a really simple question, but I haven't been able to find an answer.  I have been running my 120 V MIG welder with 0.030" solid wire and C25 shielding gas (with nice results).  If I kept all other settings constant and changed the wire to 0.024", how would the welding bead be affected?  Sorry if this is a stupid question.
Reply:no its not a stupid question, yet the answer is it will be affected.  The smaller the wire the less current needed to melt it.  Dont know your age or your personal experiences, however, if youve got electrical experience of much youll understand that the more voltage and amperage the thicker the wire needed.  Well same concept in welding.  If in your electrical circuit you run too small of a wire you can create a fire and burn up the circuit.  Add a heavier wire and youre safe.  Of course one must remember you cant just add a heavier wire and go safe, you need to have a wire matched for length and the amperage.  Ok, so back to your question.By runninga  smaller wire you will have too much current.  Therefore you will need to turn your machine down.  If you were to add a thicker wire like .035 or .045 youd need more current.  Also youre shielding gas can carry some variations, but thats not important.  C25 is real good to use.  Besides that, need to make sure you have the right drive rollers and the proper tips and liner in your whip for the smaller wire.  I dont know off handwhich sizes are interchangable and which arent.  Good luckIF it Catches...Let it Burn
Reply:Tx - thanks a bunch.  I was wondering whether I could get the weld to lay down a bit better by going to a smaller wire diameter, which I thought might make the arc hotter (?).  With the 0.030" solid wire I've been using, even on the highest current setting, it the bead forms a small dome instead of spreading out on the base metal (1/16" sheet metal).  This is my first attempt at using gas shielding and I'm amazed at the difference from flux core.  Using pretty crude testing methods (BFH), the gas-shielded weld seems acceptably strong (wasn't able to break the weld even after beating the h*ll out of the piece).  I will definitely check the manual before trying the smaller wire, though, since I don't want to damage the machine.  I'm also going to try cleaning the base metal more thoroughly before welding in case the lack of spreading is caused by contamination.
Reply:Originally Posted by Vette GatorTx - thanks a bunch.  I was wondering whether I could get the weld to lay down a bit better by going to a smaller wire diameter, which I thought might make the arc hotter (?).  With the 0.030" solid wire I've been using, even on the highest current setting, it the bead forms a small dome instead of spreading out on the base metal (1/16" sheet metal).  This is my first attempt at using gas shielding and I'm amazed at the difference from flux core.  Using pretty crude testing methods (BFH), the gas-shielded weld seems acceptably strong (wasn't able to break the weld even after beating the h*ll out of the piece).  I will definitely check the manual before trying the smaller wire, though, since I don't want to damage the machine.  I'm also going to try cleaning the base metal more thoroughly before welding in case the lack of spreading is caused by contamination.
Reply:If its beading up and your trying to fix that, you running too low a voltage...therefore if youre on the highest voltage you can get with .030 wire by running to .024 wire will need less voltage to do the same job.  Therefore yes this should help solves the problem.  You may actually find yourself running to a lower voltage, just varies.  Good luckIF it Catches...Let it Burn
Reply:all so you can try runnig an argon mix you can get a little more out of your welderChuckASME Pressure Vessel welder
Reply:Thanks for the info.  I'm running 25% CO2 / 75% argon mix now, and it seems to be good.  I have the spool of 0.024" wire sitting in next to the welder, but haven't tried it yet.  I'll put it in this weekend and see what happens.
Reply:The higher the argon content the lower the effective heat.  25 % is a good choice for low spatter and good heat.  100 % CO2 will give you more heat but at the cost of a lot of spatter.