What's the difference:

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I don't do much tig welding at all. The only machine I have which is capable is my Lincoln Tig 300/300 which is vintage 1972 and nothing wrong with it. It has AC, DC+, and DC- along with "High Frequency" selection. I've taught myself limited tig welding with it and had decent success, but these terms "scratch start, and "lift start", remain foreign to me. I've never tig welded anything steel, just aluminum. Please enlighten.Thanks,SlobPurveyor of intimate unparalleled knowledge of nothing about everything.Oh yeah, also an unabashed internet "Troll" too.....
Reply:when high frequency always on the arc will jump when you get within 0.2".high frequency always on needed when tig welding with AC.if no high frequency they then you have to touch work piece to scratch start arc.some high frequency will auto shut off once arc started as with dc you do not need to leave high frequency on all the time
Reply:Scratch start: using a plain old stick welder, scratch the tungsten on the metal to start the arc.Lift arc: (modern) touching the tungsten to the metal signals the computer to ramp up the current - now lift and the arc will start.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:My old girl will start the arc without touching the workpiece, is about all I know. I'm thinking each time I've went to weld aluminum I turn on the high frequency but I don't know if it stays on after the welding is started or shuts off. It's been a good machine I used to use a lot for stick and I've had it since 1977.Thanks,SlobPurveyor of intimate unparalleled knowledge of nothing about everything.Oh yeah, also an unabashed internet "Troll" too.....
Reply:no high frequency always on and with AC the arc will go out. it is needed to maintain arc
Reply:Not sure if this is the manual for your model :   http://www.lincolnelectric.com/asset...oln3/im265.pdfPage 6,   "TIG Welding Controls"  shows that when you set the switch to "Start only" the high frequency turns off automatically when the arc is established.   If you set the spark switch to "Off" you can practice your scratch start technique :-)Century buzzbox that I learned on 40+ years ago (was Dad's)Crappy Century 110volt mig 70 amp pigeon pooper.Lincoln Idealarc TIG-300
Reply:I believe that is the manual although I have the original which came with the machine. It's been quite some time since I've welded with it and I can remember the controls from memory but it seems I leave the high frequency on when working with aluminum.I'll have to get some practice time in as kind of foolish to own a machine and not be proficient in it's use.....SlobPurveyor of intimate unparalleled knowledge of nothing about everything.Oh yeah, also an unabashed internet "Troll" too.....
Reply:@ Slob - Jody demonstrates scratch start TIG. Notice the tungsten to filler metal contact, vice the tungsten to parent metal contact, to launch the arc. Both methods work, with the former tending to lessen contamination into the electrode.Lift/Scratch with a valved TIG torch on pipe in the field is a common technique."Discovery is to see what everybody else has seen, and to think what nobody else has thought" - Albert Szent-Gyorgyi
Reply:Simplified version: "Continuous" HF is for AC welding (aluminum and magnesium); "Start Only" is for DC welding (everything else).A few weldersA lot of hammersA whole lot of C-clamps
Reply:Originally Posted by Silicon-basedSimplified version: "Continuous" HF is for AC welding (aluminum and magnesium); "Start Only" is for DC welding (everything else).
Reply:Scratch start is generally known as scratching the tungsten with your rod as your rod is touching the work piece, basically creating  a short to get the arc started. Lift arc is supposed to let you touch the tungsten to the piece and then lift it to start your arc, but I have been stuck using crappy machines at work that don't do that so well. I've used one that has a nice function that downslopes the amps and cuts off when you pull the arc away a certain amount. That's a good feature to finish off a tie in like using a pedal.