scratch start method?

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OK tig welders can somebody explain the scratch start method to me are show a picture of itLincoln Power Mig 200Ready Welder spool gunLincoln Tomb Stone AC DCMPM 150 AMP DC portable Arc welder and GeneratorRiland 40 AMP Plazma Cutter
Reply:Just as you said scratch the tungsten on the work piece and draw it back to create an arc.   John      That is the short of it.SMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :
Reply:if you pull it too far away you will loose the arcpractice you'll get it.... like stricking with stick welding
Reply:You can only scratch start on  D C . maybe you already know that. So, that leaves out aluminum.[SIZE="5"Yardbird"
Reply:Originally Posted by Roy HodgesYou can only scratch start on  D C . maybe you already know that. So, that leaves out aluminum.
Reply:The proper technique is to scratch start on a piece of copper off to the side of your work piece.  The copper won't contaminate the tungsetn.  HF start is the way to go on aluminum.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Originally Posted by David RThe proper technique is to scratch start on a piece of copper off to the side of your work piece.  The copper won't contaminate the tungsetn.  HF start is the way to go on aluminum.David
Reply:would need to be an old penny solid copper new ones are just copper clad or use a peice of copper pipe smashed flat
Reply:Originally Posted by Go1lumLeaves out aluminum WRONG DC- 100% helium
Reply:Originally Posted by Roy Hodges..............................................................  ..................................................  ..................................I don't understand what you're TRYING to say, but ,if you use 100% helium on all aluminum , you are going to getting some awful dirty welds , if you don't add some argon for cleaning.  sorry, I did not make the rules, nature did .(i am referring to tig welds . )
Reply:Originally Posted by Roy Hodges..............................................................  ..................................................  ..................................I don't understand what you're TRYING to say, but ,if you use 100% helium on all aluminum , you are going to getting some awful dirty welds , if you don't add some argon for cleaning.  sorry, I did not make the rules, nature did .(i am referring to tig welds . )
Reply:with practice, you can scratch (gentle stroke- more like stroking an angry cat) start on the work without wrecking the tungsten. if you want to try starting on something else then a carbon brush works better than copper. the tungsten won't stick to it- i remember trying a piece of copper and simply having it stick to the tungstenRoy, argon doesn't provide any cleaning action- like helium it's an inert gas. the cleaning action comes from the EP phase of AC. with 100% He and DCEN it's the lack of EP that causes the dirty look but it's just on the surfaceGo1lum, have you ever tried scratch start with Al, DC 100% He? i would have thought that even with a carbon striking block getting the arc going would be a nightmare due to the He
Reply:instead of using copper or literally scratching the tungsten just rest the cup on the material and drag the rod across material and tungsten.ill post a picture in a minute.6G zirconium 702 GTAW 2" xxheavy6G P.E.D. carbon steel GTAW 2" xxheavy3G titanium Gr. 2 - Gr. 7 GTAW up to 3/4" 3G 316L stainless GTAW up to 1" 3G carbon steel GTAW up to 1" 3G Hastalloy GTAW up to 3/4"1G tantalum GTAW up to .060"
Reply:sorry about the size and my lack of paint skills but this should give you the idea.It works well for me and you won't get contamination on the tungsten or not as much as scratching on the material.6G zirconium 702 GTAW 2" xxheavy6G P.E.D. carbon steel GTAW 2" xxheavy3G titanium Gr. 2 - Gr. 7 GTAW up to 3/4" 3G 316L stainless GTAW up to 1" 3G carbon steel GTAW up to 1" 3G Hastalloy GTAW up to 3/4"1G tantalum GTAW up to .060"
Reply:Ya mean like striking a match?  If you scratch start AC, what do you do on the next cycle.  With sine wave, the HF needs to run all the time or no arc.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:not sure about ac all i know is that the arcwelder that our scratch arc is hooked to doesnt have high frequency so its a no go6G zirconium 702 GTAW 2" xxheavy6G P.E.D. carbon steel GTAW 2" xxheavy3G titanium Gr. 2 - Gr. 7 GTAW up to 3/4" 3G 316L stainless GTAW up to 1" 3G carbon steel GTAW up to 1" 3G Hastalloy GTAW up to 3/4"1G tantalum GTAW up to .060"
Reply:Originally Posted by pulserTIG DCEN 100% Helium is actually a great method for welding thick aluminum.  But as you say, you do not have the cleaning action of AC welding.It is the DCEP portion of the AC wave form that is responsible for TIG aluminum cleaning, hence the balance control on AC TIG welders.There may be a difference in the AC cleaning effectiveness, using Ar versus He, I have never seen a discussion on this, but as I understand it, it is the electrons leaving the surface of the alumium base metal that act to remove oxide, so the gas should have little effect.However, He has much better thermal conductivity than Ar, so at the same current the He weld is hotter, and at a given arc length, He runs at a higher arc voltage than Ar, so again this makes the He arc hotter, so possibly, at a fixed current and arc length, the He AC arc may have better cleaning?
Reply:As for the cleaning action of argon. If you run diferent gases you get diferent results. CO2 gives penitration, argon gives cleaning I have seen nitrogen run on a mig and it is just crap so inert or not they are not the same. Steel usually uses 75/25 argon CO2 that gives you penitration with cleaning. Aluminum requires 100% argon or ar he blend because cleaning is the most important thing in aluminum unlike steel. Yes yhe ac gives better cleaning but that is not the whole story. I run argon on my MIG and if I run 75/25 I get a light black soot on the edges of the HAZ when I run AR everything just shines. As for the scratch start if you are quick you can lift the electrode befor contamination it takes practice. My Miller uses lift start and that just rocks all I do is stick it down and pick it up and I got an arc. I have had some sucsess doing a lift start type of move with scratch start it just depends on you and the machine. Steel Thunder Welding LLC. St. Thomas VI USAMM350PBOBCAT 3MAXSTAR 150 STH375 EXTREME PLASMA6.5 HP COMPRESORDEWALT 18, 24, AND 36 VOLTO/A TORCH SETAND SO MUCH MORE I DONT REMEMBERALL IN MY 2005 2500HD EXTENDED CAB L/B
Reply:Originally Posted by welder155sorry about the size and my lack of paint skills but this should give you the idea.It works well for me and you won't get contamination on the tungsten or not as much as scratching on the material.
Reply:your welcome. my teacher taught me that because i was just tapping it on the base metal and had to sharpen the tungsten every time so this works much better.6G zirconium 702 GTAW 2" xxheavy6G P.E.D. carbon steel GTAW 2" xxheavy3G titanium Gr. 2 - Gr. 7 GTAW up to 3/4" 3G 316L stainless GTAW up to 1" 3G carbon steel GTAW up to 1" 3G Hastalloy GTAW up to 3/4"1G tantalum GTAW up to .060"
Reply:Originally Posted by Go1lumThe cleaning action comes from the ions bombarding the base material. Not from electrons flowing through the material