Stainless pipe cap problems

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Hey guys, I have little experience welding pipe and am trying to practice to hopefully open new doors for my carrer. I have been practicing on 2 inch stainless pipe in 6g and I can get my root and hot pass in there decent but im having a hard time with the cap. Really, its kickin my butt. I let the pipe cool completly between passes and keep the purge running during each pass. It seems im getting the cap too hot as its turning gray and im getting undercut. I figure i also must be going way too slow. im using a 1/8 gap feathered edge running everything at roughly 75 amps using laywire. Im am not walking the cup it it matters. I was wondering if the more experienced people had some tips, or if there was a video out there of somebody doing a tig cap that i could watch cause im very much a visual learner. Thanks a lot in advance.
Reply:Cup size and CFH? What is your amperage on the cap? How thick are the walls of the pipe? Filler wire size? Some things to try without more info- Move faster, push more filler into the puddle, hold the arc length as tight as you can, don't lean the torch back too far.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:I was running roughly 20 cfh with a 6 cup. Amps around 80 with 1/8 filler. I try not to change the angle of the torch but im sure there are times im not paying attention. Thinking back, i think it was schedule 40 Pipe. Im not quite sure tho. It was scrap pipe i found. I had it set up in a turner that was about two foot off the ground and i really couldnt get comfortable starting at the bottom. That prolly had a lot to do with it. And i was trying to use a foot pedal which is hard for me in a crouching position. Like i said, im inexperienced with pipe as we never do pipe at work.
Reply:2" schedule 40 is about .154" wall? Try to fill to just under flush before the cap. On the cap I would use around 110-125amps on something like that, depending on how much more it needs filled. I know its hard to keep the tungsten at the right angle, but it really does help allot. Have you tried scratch start without the pedal? That would be one less thing to worry about while you are learning. Just need to change the way you start/end the weld.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:if youre using a sycrowave, you can set the machine to start and stop the arc at the touch of the pedal. ( I can remember what this setting is called) basically you push the pedal down and let off to initiate the arc and push the pedal down and let off again and it will stop.  when in this setting, the amp will stay constant like scratch starting, but not having to actually scratch it.  im sure Lincoln tigs have this setting also, but I don't know what models do though.....  hope this helps....BarnabieSnailHouse_Projects--For All Your Turbo and Off-Road Needs Import and DomesticMiller Dynasty 200Miller Syncrowave 250Miller 251Lincoln 250'69 Lincoln SA-200 MILLER KILLER!Thermal Dynamics PlasmaPakmaster 100XL
Reply:Originally Posted by SnailHouse_Projectsif youre using a sycrowave, you can set the machine to start and stop the arc at the touch of the pedal. ( I can remember what this setting is called) basically you push the pedal down and let off to initiate the arc and push the pedal down and let off again and it will stop.  when in this setting, the amp will stay constant like scratch starting, but not having to actually scratch it.  im sure Lincoln tigs have this setting also, but I don't know what models do though.....  hope this helps....Barnabie
Reply:Scratch start all the way. Forget the pedal. Set the machine and go.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:Thanks guys for everything. Im gonna try the scratch and try to get more comfortable. I aint gonna let this whip me hahahaha