starting out; overpenetration

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Forgive me if this has been covered many times over -- there wasn't an experienced welder in the shop tonight.. so no picking the brain of the local.  Hoping somebody can help me out before my next practice session.I just got started tig welding & have been trying to just lay beads.  I had a mix of mild steel rectangles ranging from 16 to 20 gauge.  1/16" rod (as the 3/32" was being even more of a pain).  I forget the exact number, though I can get it if it makes a difference.  Welder is in the DCEN position.I start the pool and get it a bit wider than the stick.  Once everything is flowing, stick the rod in & back out a bit, move forward 1/2 a bead.  It works for a few repetitions, but then I really have to back off the foot pedal to keep the pool from getting very wide.  And once I do, sticking the rod in will cool the metal down too much or the pool never gets wide (but overpenetrates).  I think I want a wider pool with less penetration.  Am I just not working quickly enough, or is there something fundamentally wrong with my strategy?As a side note, I can also see weird stuff sort of float in the weld pool.  When it solidifies, it looks like a dark spot on the side of the weld.  The first day, I described it and was told I'd contaminated the tungsten & that sharpening it will get rid of that.  Could it also be coming from the steel itself?  I don't really clean it ahead of time like I know I should.  (How do you even clean 18 gauge sheet metal the size of a credit card?  A grinder seems like a sub-optimal option).Thanks in advance for the help.
Reply:Base metals should be cleaned prior to welding. Especially tig welding. When working with smaller diameter coupons and/or thin Gage, a wire brush or wire wheel works well. Your penetration problems sounds like too slow of a travel speed. Also, sounds like you are relying on, expecting too much from having a foot control. I suggest practicing with no remote amp control, panel setting only. This will teach heat, puddle manipulation by way of motor skills.Miller TrailBlazer 251Miller HF-250-1Miller MaxStar 150 STLHyperTherm PowerMax 380 plasmaLincoln PowerMig 180Millermatic 252Miller Diversion 180
Reply:get some heavier metal , if you can, 20 ga is easy to blow through(overpenetration?)..as you notice, the heat buildup needs to be met with heat reduction..but not too much...make sure yer arc length is short or you wont get a puddle quick enough(should come in one second) and you'll just sit there pouring in heat..
Reply:Originally Posted by tab126(How do you even clean 18 gauge sheet metal the size of a credit card?
Reply:i thought "over penetration" was a good thing we the uneducated have been led for so long by the inexperienced, that we feel we can do anything,with nothing~Miller Syncrowave 200Miller 251 mig
Reply:my first newbie instinct is your filler is too big for the thin metal. Thicker metal or thinner filler.  Try mig wire for material that thin...miller syncrowave 250hobart handler 140home made 400 amp engine driven in progress...
Reply:On stuff that thin you would have better luck with some thin wire like .045. 1/16" works fine but you have to have lots of control cause you dip extremely close to tungsten. That thin and your tungsten needs to be extremely close to work with tight arc or else it fans out wide and you put too much heat in. Takes practice really, thin stuff is always tricky no matter the process.Millermatic 252Lincoln 175 plusTA 185tswTA 161stlhypertherm pmax 45Victor torchHenrob torchAn S10 for each day of the week
Reply:On metal this thin(20gauge) their is a tendency to grind the edges to much making it thinner, may want to leave a small gap and run some beads without filler to get your technique down, may have to start with some filler, er70s-3 or s6, in .030.You have to think about this stuff before you begin welding based on prior beads, gets to hot then back off with the heat, keep it minimal because you next have to contend with warpage and upset.
Reply:Why would you use S-2 over S-6 for this application, or any other application.  JGSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :
Reply:Your filler is right and your heat sounds right from what you describe. The problem you have having is an inherent problem of welding steel and that fact that it is thin merely exacerbates the problem. If your weld is structural then you are stuck using a mild steel filler in which case you will never eliminate your problem entirely. You can control it to some degree but not eliminate it altogether. If your weld needs to be strong but not it a structural fashion then you should use silicon bronze rod and you won't have the trash issue any longer, the puddle freeze up, or the major burn through. I have done it both ways and never once had a perfect steel weld using steel filler, unless it was stainless. Something about the silicon bronze calms the steel and pushes the trash to the sides of the puddle so you can control the weld.
Reply:may want to leave a small gap and run some beads without filler