For those of you that go to Harbor Freight and buy a gas welding set and try to weld up .035 wall 4130, Study the chart below and check your tip size. Most tips that come with Basic gas welding units are not good for anything below 3/16″ thick material and the difference between the proper size tip and one that is way oversize is extreme. If tip is to small it is easy to tell, no mater what you do it will not quite melt the metal to allow a weld puddle to form. In this case, the next size larger tip should be about right. Welding .035 to .035 uses one size tip, welding .035 to .065 uses a different size tip and welding .035 to .090 required an even larger tip. Using proper size tip and proper gas pressures make a major difference in difficulty when gas welding.