Hi Alison,
I don't know what to tell you about your concerns with the possibility of a variation in your wire diameter. I've never heard of such a problem, but over the years I've only used either Lincoln or ESAB. Here's a few things you may want to check out regarding your setup. A couple of these have been already been mentioned:
Good wire feed starts at the drive rollers. Check that the driving roll has the right size V groove to suit the welding wire, and that the groove is not worn. Good quality welding equipment will feature a driving roller at least 30mm in diameter, with a precision machined wire groove. Smaller diameter driving rollers may not provide sufficient grip onto the wire. Often the first reaction to poor wire feeding is to increase the clamping force applied to the drive rollers. However, excessive clamping force will deform the wire and roll a tight curve into it, which only adds to the problem.
Also, as the wire passes through the gun liner, over time, contamination from the surface of the wire builds up inside the liner, slowly increasing feed resistance to the wire passing through it. Liners often get clogged over a period of time. This results from either the fill falling out, wire lubricant rubbing off on the liner, or infrequent change outs of the liner. If the fill is falling out, you may have sharp bends in the gun assembly or the wire is being bent coming out of the payoff pack. In some rare cases, the wire lubricant packs inside the liner. Quite often it is advantageous to put a cleaning pad ahead of the feeder just to prevent excess lubricant or dust from entering the liner. Steel Wool or Scotch Brite pads work great, but the pads that can probably be found in your local weld supply shop are pretty inexpensive.
Liner blockage is often another cause of wire feeding problems too, and when it occurs the liner really should be replaced. When installing a new liner, pay close attention to the manufacturers recommendations. A liner cut too short may not align correctly with the gun tip, leading to more wire feed problems. Wire surface contamination can be reduced if the welder has a fully enclosed wire feeder, which of course protects the wire spool from dust or grindings present in the air, and from surface deterioration due to moisture. The contact tip is where the welding current is transferred onto the welding wire, so for good welding conditions, the wire must have constant contact with the tip. As the tip wears, the current transfer becomes less reliable, and again the arc becomes erratic.
In many cases an oversize liner is chosen for a gun assembly with the intent to make things loosey goosey on the inside of the liner. The practice is well intended, but the outcome can be disastrous. Wire stacking can occur in these assemblies when a particularly soft wire has room to bend inside the liner itself and not conform to the liner curvature. To avoid this problem, choose the liner with an inside diameter at slightly larger than the wire diameter, leaving very little room for stacking. .010" to .015" clearance if you can get it.
The last thing you may want to look at is the gun assembly length. Often the longest gun assembly length is chosen to cover all aspects of welding positions and fabrications. While this is a good idea, occasionally the long length assemblies, i.e. longer than 15 ft. result in feeding problems. It's just too long and too much resistance.
Most wire feed problems can be resolved by making sure the drive roll groove is not worn, by replacing a dirty or clogged gun liner, by not applying excess clamping force to the drive rollers, by replacing worn contact tips, and by protecting the wire from contamination.
You might try (as Chet stated) the .035" tip. That extra .005"(about the thickness of notebook paper) is not going to hurt anything and when (as Chet stated) the welds are long and continuous or running higher amps, the tip will get hot and the wire may bind in the tip with the .030" tip.
I agree with Bill!
Forum
