TIG Weld Porosity in a Plug Weld

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Long time occasional lurker that has been beaten. I am trying to salvage a machine project.  It is basically a hollow shaft, 3/4" ID and 1.5" OD with a unwanted 1/2" diameter hole drilled perpendicular to the shaft.I have slipped a short piece of 3/4 OD rod inside the shaft and want to make a full penetration plug weld at the hole and then I will drill and bore out that 3/4" OD rod leaving no void where it has been "filled".The hole has been beveled out so I can get the tungsten down into that bottom corner.The problem is any which way I try and weld it I get porosity right off before I even get a weld puddle.I can weld the shaft or the rod easily with no issues with all settings the same, but in that blind hole I can't.Everything is spotlessly clean, no scale etc, both 1018 mild steel, gas lens, same flow, same settings, same tungsten projection (less the 1/2" to reach down there), DC neg.  So I think that rules out leaks, bad argon, bad ground, etc.Am I getting arc blow down in that hole?Or is it gas turbulence? Tried more gas, less gas,,,, nothing helped.Any suggestions?
Reply:I am no expert, but it seems like trapped argon, try turning your gas flow down and see if that helpsMillermatic 211Miller Syncrowave 350lx with cooler and tigrunner Thermal Dynamics cutmaster 811955 National Cylinder Gas O/A setup with original patina
Reply:Originally Posted by juanniAm I getting arc blow down in that hole?
Reply:are there cutting fluids stuck in there creating their own gases? try turning the flow down on your torch (way down) and running a remote (purge line) to the inside. Does your high frequency turn off? may be having issues with the arc jumping around to all surfaces. maybe turn off your HF start switch, and scratch start that arc in the corner.'14 HTP invertig 221Thermal Arc 201ts'15 HTP 2400'13 Hypertherm Powermax 30Esab 875Esab 251Clark Metal Servicespecializing in stainless steel exhaust systems
Reply:Originally Posted by sausage450rare there cutting fluids stuck in there creating their own gases? try turning the flow down on your torch (way down) and running a remote (purge line) to the inside. Does your high frequency turn off? may be having issues with the arc jumping around to all surfaces. maybe turn off your HF start switch, and scratch start that arc in the corner.
Reply:What is the shaft being used for? Is bronze or silver brazing with OA a possibility? Since you are already machining it again I would thing about brazing in a 1/2 inch plug and the smoothing everything out.
Reply:Originally Posted by npg170What is the shaft being used for? Is bronze or silver brazing with OA a possibility? Since you are already machining it again I would thing about brazing in a 1/2 inch plug and the smoothing everything out.
Reply:Try A lot less gas you don't say what you have been running for flow but if you are going straight down you will need very little. tap the pedal once or twice to displace what is in the hole and go to town. With a Gas lens I would try 3 or 4 CFM any more and it will be blowing back in your face. that low you should not be able to feel it more than an inch or two away.Syncrowave 180 SDMillermatic 250XSnap On MW 120 Econopac 50Victor O/A with some Smith Attachments 30 X 50 shop with a 400 Amps