Been lurking here for a while. Advice from this group's past posts lead me to buy the Millermatic 251 MIG. The 251 replaced a Century
120VAC unit. Obviously this was a big upgrade for me. I am *very* happy with the new unit but I am having a small problem that the group may be able to help me on.For my first big hobby project, I am rebuilding my utility trailer. I'm using new 3/16 mild steel, .030 wire, argon/co2 gas and voltage/speed from the miller's chart. When I first pull the trigger, for the first ½ to 1 second of welding, it pops and cracks. The gun pushes pack at me. Then after the ½ to 1 second after start, it smoothes out and makes the correct sizzle sound (music). The weld quality at start is poor (no penetration) and then smoothes to a good quality weld (for me). The transition from bad to good happens fast, like someone turns on the turbo charger.
Some initial thoughts: After the purchase of the welder, I upgraded the house to 200 amp service and ran 4 awg out to the shop, so wiring shouldn't be the problem. The 251 has a "Run-in wire feed speed setting". I checked and it was set to the factory 100%.
One thought was that the argon/CO2 had not made it to the gun. I read in the group's archive about adding a switch to turn on the gas and purge the line before starting to weld. One piece of evidence that tells me that this is not the problem is that it happens every time I start the weld, even if I have only paused for a few seconds. The gas would not dissipate in the tube that fast.
Any Ideas? I plan to do some input voltage measurements with a memory volt meter. I will also try some over V and Speed setting.
Thanks in advance.
Humanfuse (I'm no stranger to electrocution)