Tig&OA - penetration vs warping

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In class, I've managed to get good penetration with an OA torch welding coupons with minimal warping. Using the same material (18 or 16g mild steel, forget exact thickness) on my Dynasty 300 tig at home, the only way I can get good penetration is to increase heat, to the point where after its all done the warping is more severe.Whats wrong with my tig technique? With OA you can dial down the heat and just stay in the same place a bit longer until the puddle is formed. I tried that with my tig, but it doesn't seem to work, the arc is there but no puddle until I increase the heat which brings us back to where we started. Maybe higher heat but go quicker? Then loosing the puddle becomes an issue.I'm just not sure where to start or what to focus on. I know I can use the pulser to help heat control but I'd like to get my technique proper before going that route. Or is warping just "nature of the beast" with tig due to something else I'm not aware of?Also another bit of info to add - at home I'm tig-ing over a 1/4" aluminum plate, OA at school is done over these yellowish looking brick.
Reply:Warping will tend to be higher as there is less preheat on the plate, as TIG results in a more localized heat input.  Clamp down what you can.  Put a slight bevel on the plate if need be.  Keep a TIGHT arc length, as the further away you are, the less penetration you'll get.  Use the smallest filler you can get away with.
Reply:if your parts are resting on an aluminum plate at home, you're welding on top of a huge heat sink.  Contact with the aluminum plate will suck the heat out of your weld joint very quickly.  Try to get the weld up in the air, so there's nothing touching the vicinity of the weld.  Refractory brick, like you're using at school, isn't too expensive.  Try the phone book for a local masonry contractor/fireplace store/ or similar and buy a few pieces to use at home.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:look at the post i started  herre on 9-11 call t joint tig questions.. as supe says, hotrodder  posted fotos showing the effect of arc length..short arc length=easier said than done im findiiiing..
Reply:I thought the heatsink was a good thing to keep the heat out of the material. But I can see it causing more heat needed to be put in to form a puddle. I have a slab of firebrick left over from the fireplace, will try it out. Grounding may get tricky.Keeping the arc short is indeed difficult, something to get used to vs the OA. Blew through that first tank of argon pretty quick trying. For the filler, I'm using ER70S-6 MIG wire - there were 2 sizes at home depot, I got the smaller - 0.025" I think? As per another tip I found on here, I cut a length, folded in half, one side in a vice and one in a drill chuck. After a couple seconds of twisting they were tightly wound together and stiff enough to handle easily.