Welding a crappy casting?

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Ok guys I am a novice TIG welder, and I am having some issues with welding these crappy castings that these kids keep bringing me. Specifically blow off valve flanges that need to be welded to inter cooler piping. I get them done, but they look terrible since I am having to fill holes in the castings. Is there any trick to it or do I just tell these guys buy a real flange? I am using a Dynasty 200DX so I am able to adjust for the oxidation, but is there something else I should do?"If you live in Sacramento you have seen my work."
Reply:the flange / bov probably comes as a set from the cheapest region of ebay...I am in for the answer as I never thought the castings would be so poor.  The BOV's I have worked with have always matched a standard flange - small piece of 3/8 - 1/2" aluminum or steel with 3 or 5 holes drilled in it.miller syncrowave 250hobart handler 140home made 400 amp engine driven in progress...
Reply:On cast aluminum I usually start with these settings75% electrode neg60-120hz, some castings seem to respond better to the softer arc of the 60hz but very rarely do I go tha low. 4043 fillerClean with lacquer thinner1/8 tungsten 2% lanthI will set the machine at the max amps (200) and just use the pedal to get just what I need. I will also work into the hea a little slower then if I was working with solid aluminum. I can't say I have ever had a aluminum casting I was not able to weld because of quality.-DanLast edited by engnerdan; 11-02-2010 at 03:11 PM.OwnerDW Metalworks LLCMiller Trailblazer 302Miller 8RC FeederMiller Passport PlusMiller Dynasty 200 DX W/Coolmate 1Hobart Handler 135Hypertherm PowerMAX 30Smith O/A Torch SetPlus much much more
Reply:key words might be "aluminum casting" - I would not be suprised if the chinese knock of tials are made with "any metal that can be poured into a mold"miller syncrowave 250hobart handler 140home made 400 amp engine driven in progress...
Reply:Watch out for over-penetrating into the inside of the boost tube, if its not pristine clean inside.  Especially if the tube has been used, it will likely have some oil film inside it that if your puddle penetrates all the way over to it, will cause immediate porosity in your weld.The only problem area I had when welding this one pictured, was the only spot where my puddle penetrated all the way to the inside of the tube (which had not been drilled, and cleaned only on the outside.)After you drill the hole, you can look or feel inside there to see where your weld bead penetrated all the way through.  See if there is a correlation between where you believe the casting had a void, and where your weld bead penetrated through to the inside of the tubing. Attached Images
Reply:Thanks for the help guys. Dan I will give those settings a try. I have made a few bolt on flanges from good billet stock before, but recently I have got a couple of real bad parts. They have been the SSQ style with the clip in style, like the one pictured above, so I could not just make it real quick.Maybe I will make a couple and keep them on hand."If you live in Sacramento you have seen my work."