I use ahobart 140 and it works great for anything upto 3/8 single pass.  I had a neighbor (pro-bike builder) come over and check out something I was building he laughed saying there was no way it was penetrating properly, he then checked things out and admited he was wronge and that he was impressed by it!  So if you can afford a good 220 go for it but if you cant get a good110 if you use good technique you will be able to do anything you want.  I know someone who   built their whole  rig with a 110 including lincon lockin his 14 b with 44s and hasnt broken any problems.