TIG Contours

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Hello Everyone;This is my first post and I really enjoy the forum.  I am a senior taking TIG at a junior college for fun during my retirement.  I really enjoy learning the skill required for TIG.  We are being taught drawing symbols and a few questions have come from lab welding 1/8 steel:1.  The instructor put down a demo bead next to mine and his bead looked more "shiny" than mine.  Can anyone explain?  He said another student had just asked him the same question a few minutes before and he is not sure why.2.  Drawings can require concave, flat, or convex.  Are there special settings/techniques required to achieve the different contours?ThanksTedMillermatic 252Hypertherm Powermax 45TIG in the near future
Reply:He would probably have to watch you lay your bead down from start to finish, so he as an experienced instructor can note what you're doing different than he is.  Likely related to work piece temperature, arc length, torch angle, etc--anything that dumps unnecessary heat into the workpiece will have it oxidize as soon as the argon coverage dissipates.Last edited by Oscar; 10-05-2013 at 09:36 AM. 1st on WeldingWeb to have a scrolling sig! HTP Invertig 400HTP Invertig 221HTP ProPulse 300HTP ProPulse 200 x2HTP ProPulse 220MTSHTP Inverarc 200TLP HTP Microcut 875SC
Reply:Oscar, I think we agree on this - Instructor could be using more amps with faster travel speed since he has more experience.Students could be going slow and cooking it.Amount of fill determines convex, flat, concave. All other things being equal. Concave is another way to say under filled.Dave J.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Yep the others are probably right, the instructor is putting less heat into the steel. People new to tig often hold a long arc length, which causes more heat to be put into the steel and they also weld slow. New guys also like to hold the tig torch angled back too far so that they can see, but that causes the argon to leave the weld too soon.Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Thanks for the replies.  I will follow up on the suggestions.TedMillermatic 252Hypertherm Powermax 45TIG in the near future