[cruzin-n-fusion]

i was givin a weldcraft tig torch and a box of tungstons by my forman who was a boiler tube welder, but from every thing i see in videos they are all foot pedel operated or some other fancy torch with the operation on the torch its self . is scratch start obsolete ? or is it still used in some practices if so where ?

[kermdawg]

Its far from obsolete, cept maybe in the shop. Out in the field its very difficult to operate a foot pedal while standing up. Lots of piping companys still use scratch start tig machines because they will do a tig root pass and 7018 stick fill/cap passes.

But, for the home hobbyist or shop welder, foot pedals usually win out. Think about the price too-you can get/convert a scratch start welder for well under 1000 dollars. Most of your tig machines with a foot pedal are in the range of 1000-2000, depending on the controls, again which yuo wont have with a scratch start more than likely.

As far as actual welding goes, pretty sure the only thing you -cant- scratch start on is aluminum. Mild steel and stainless are weldable with a scratch start.

[Otto Nobedder]

I learned TIG on lift-arc, didn't have any remote. As kermdawg says, this is the way it's done in the field.

Scratch-start only "contaminates" your tungsten with the parent metal of your weld, so the only harm is in particles on the tungsten diffusing the arc somewhat. Be sure to scratch within the weld zone, as with stick, so you don't have arc strikes outside the weld.

Without a remote, you need to find a setting that works for you in all positions (if welding pipe), and control your heat input with your speed.

Steve

[cruzin-n-fusion]

i still have a ways to go till im tigging in root passes in pipe, i just started welding school so im working on my virtical and overhead plate right now , i would however like to at least get the feel of runing passes on plates is that usually the next step before i go to pipe? or does it vary between schools ? there is so much to learn and i want to now it all, so you guys on the forum help me out a lot , as class goes on youll be hearing plenty of questions on this board . thanks again -- C-N-F

[kermdawg]

Are you doin tig or stick?

Usually in schools they start off with stick in all positions on plate, then they'll put a piece of pipe on top of a plate and you'll weld the pipe to the plate(not sure what if they got a special name for it or anything). Then you'll do pipe 1g, than 2g, than 5g, than 6g. Google the positions, but remember pipe positions are differant from plate positions.

With tig(what I went to school for. Learned stick myself/from some old hands in the field so I never had the "formal training environment"), we started off with some 11 guage coupons and a foot pedal on mild steel. We just did flat but we did all the joint configurations (butt, lap, outside corner, T). Then we did em all on SS and aluminum. THEN we moved onto a scratch start and pipe.

If you can weld pipe with a stick welder than you can do it with tig, as long as you know what your looking for (breaking down the walls on the root, good tie in on the hotpass/filler). Hardest part for me tiggin pipe was the cap cause its really hard to walk the cup, so I learned to freehand the cap, and after I learned to freehand the cap I kinda liked it better for the root and fill too, especially on the bottom of the pipe.

[rickbreeezy]

As far as actual welding goes, pretty sure the only thing you -cant- scratch start on is aluminum. Mild steel and stainless are weldable with a scratch start.

Not to be a dick, but for the purposes of education, aluminium can be welded via the scratch start method, given the machine has the appropriate settings for welding aluminium. Granted though, this is no x-ray welding method, and the first ripple always seems a bit contaminated. And of course a foot pedal is highly preferable.

just sayin,

-Rick

[kermdawg]

Im not arguin with you Rick. I was always told that you couldnt use scratch start with aluminum due to contamination issues. Obviously you -could-, but its not recommended, right?

[rickbreeezy]

Exactly! do-able, just not recomended. Really is just the starts and stops that seem bad, the tungsten seems to burn off the contamination of the aluminium after the firtst 1/4 inch or so. But re-grinding the tungsten every weld is hell in a handbasket!


-Rick

P.S. thanx for not getting all egghead on me.

[kermdawg]

Egghead?

[Otto Nobedder]

...hell in a handbasket!


-Rick

I thought Helena Handbasket was an arts & crafts studio in Montana.