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Scratch start TIG

Posted: Sun Jan 13, 2013 10:49 am
by nickn372
I'm setting up my vast array of welding tools with the capability to scratch start tig now as well. Is anybody familiar with tigging in this way? I know Jody has a few videos of it and i watched them but I'm just fishing for a little more advice or experience. I intend to practice up a good bit before I do any work but I'm just looking for some good pointers or guidelines.

Re: Scratch start TIG

Posted: Sun Jan 13, 2013 3:01 pm
by weldin mike 27
Hey,

Its a nice simple way of tigging. Just remember to use a very gentle action to start but a real quick "snap and twist" to break the arc at the end without leaving an arc trail. Dont forget that torch is always "live" like a stick electrode and to turn your gas valve off in between welds.

Mick

Re: Scratch start TIG

Posted: Sun Jan 13, 2013 4:39 pm
by nickn372
Kewl and simple just like I like it. It makes the repair work I do simpler.

Re: Scratch start TIG

Posted: Sun Jan 13, 2013 5:22 pm
by Otto Nobedder
Both scratch-start and lift-arc have the possibility of leaving contamination, especially if you "stick" it. Just like stick-welding, it happens sometimes.

I generally try to start my arc at what will be the edge of my last pass, so I don't leave arc-marks outside the weld zone or tungsten inclusions within the weld.

Most of the time, this isn't critical at all, but it's a good habit to get into so you don't have to think about it when it IS important.

The technique I learned for breaking the arc to avoid cratering and keep gas coverage as long as possible is to slowly roll the cup so the tungsten is at a steep angle, while backing away at 45* so the arc diffuses. Once the arc approaches the width of the weld, I then snap away quickly.

Steve S

Re: Scratch start TIG

Posted: Sun Jan 13, 2013 6:25 pm
by nickn372
Ok thanks! Now all I need to do is practice up a bit...

Re: Scratch start TIG

Posted: Mon Jan 14, 2013 1:11 am
by TamJeff
If your machine has a remote function, might as well take advantage of it. Doesn't mean you have to use a pedal. This is even more convenient than scratch start, just for not having to mind the gas alone. This is a switch from miller, but a micro snap switch from radio shack would work as well. The other advantage, outside of avoiding contamination is, you get to pulse off the final crater and is especially handy when you have a lot of tacks to perform on builds consisting of many parts.

Image

Re: Scratch start TIG

Posted: Mon Jan 14, 2013 2:16 am
by nickn372
I have 2 separate machines that i need to keep my equipment interchangeable on. A miller 301g and a 1975 black face SA200. All of my stuff will work on either engine drive. I am a fully portable set up and need to keep my tools simple yet effective. Thanks for the suggestion though jeff! I may look into modifying something with my spool gun module to add an on/off contactor to the hot lead.