I will disagree with this totally. As a professional pressure welder I do code quality work on all alloys from carbon steel to stainless, Inconel, Monel and Hastelloy with no problems at all using basic scratch start Tig equipment. All our pressure piping and vessel work is done to ASME code and inspected accordingly. In the hands of a skilled welder a scratch start Tig can be started without contamination of the tungsten. I've only been welding with the scratch start method for over 30 years
Yeah, normally you need a puddle to generate contaminants. I guess if you stopped and started right up again, maybe....
I would do the trade, scratch start is not the easy way to learn, but if you keep at it, you will learn the right way to do prep and setup (two of the most important parts to a nice weld). Take what you learn with that machine and move to an HF and you will be that much better.
One other thing I'll throw in here...start off with something thicker, 1/4 or 3/16 and work your way down to the thinner metal.If you cant find some new scraps, at least grind the rust and paint off until you have clean metal. If you really hate yourself start on some thin old rusty car body and try to TIG it.
Scratch start is a misnomer. Someone just starting out and hearing scratch start, they picture striking like a match to get started. This is not correct. the Tungsten tip should never touch the metal being welded. The arc is started without actual contact. The contact is what causes contamination of the tungsten tip. Getting the tip close enough to arc without touching is correct.
I didn't say scratch start doesn't work. And like I already said, for some jobs it's not a big deal. It doesn't matter who does it or how much experience that person has, touching the tungsten to metal(and a lot of other things) contaminates it. With all your experience I'm surprised you don't know there are welding jobs where NO tungsten contamination is allowed. I haven't done any of that work myself. The info comes from friends who have done aircraft and aerospace welding. An ex co-worker who had once welded on nuclear reactors told me the same rule applied to that field. The best of my race car fabrication friends impost that same standard on themselves. Agreed, a hot rod is not a spacecraft, race car, or nuclear reactor, but why intentionally introduce a known shortcoming that is easily avoidable?
I know the jobs you are talking about and did them for many years with no tungsten contamination. Tungsten contamination looks like a speck of black foreign matter in a radiographic examination (x-ray picture of a weld) Welding on ASME code pressure vessels and piping with no tungsten contamination is easy, we do it as a matter of routine with scratch start Tig equipment on conventional CC welding power sources. Tig welding work to any code in existence including nuclear can be done with scratch start Tig. As I said before, a skilled Tig welder can use a scratch start Tig with no issues regarding tungsten contamination. How many times, or how many ways do I have to say it before it sinks in ?
It won't sink in to a novice or non welder that is for sure. I started many years ago with scratch start and no pedal.When you get a h/f start and pedal you think you have died and gone to heaven. You can start scratch with small copper plate as well,but some posters here will "po po" that also "lol". Miles of root passes have been done with tig scratch start.Too many armchair welders. My 2¢ T
I may be wrong but don't most of the cheap inverter TIGs require touching the work to complete the circuit in order to start the arc?
The open circuit voltage between the tungsten and ground varies with the machine, but it's typically about 110 volts. While welding it's considerably less. Using the standard rule of thumb that 10,000 volts will arc across a distance of 1", 110 volts will "jump" .011". I suppose now someone will tell me they can get the tungsten less than 11 thousandths on an inch from the work, every time, without touching. Just like writing on paper with a pencil, anytime the tungsten touches metal(and assorted other things) that material contaminates the tungsten. That the welder perceives no contamination doesn't mean the tungsten isn't contaminated. ANY contamination of the tungsten has an effect on the weld. No amount of knowledge, experience, or certification can change that. You guys can, convince each other you know everything. You can call me a novice, non-welder, armchair welder, and do whatever you can to minimize the facts or discredit me, that doesn't change reality. Experience is good, but when a person already thinks they know everything they aren't in a position to learn. Because of that, I am apparently supposed to accept what you believe? Although welding is not my primary trade, I have welded a LOT. However, I HAVE worked with a number of welders who claim to have been from Maine to Spain and Boston to Austin, and believe what they don't know isn't worth knowing.
A lot of words to say practically nothing. If you won't take the word of a pro ( and a few others too) then there is no point to any of this. Like talking to a fence post, just as productive.
On the other hand, you sidestep the points I made and claim your practical experience trumps reality. Seems that fence post remark works for you.
any stick welder will t.i.g. tungsten inert gas .hook up the torch or tig rig to negative the ground lead or work piece is actualy the positive . and the scratch start you hold the filler wire in your hand and with a striking motion with the wire kind of a filck you srike the arc,light and fast against the side of the tungsten ,this will not contaminate or distort the tungsten, 30 years of piping and fab expierience
That's really funny, and it's a lot more informative than responding to the points I made. But I understand, I'm a dumb ass, and you are a genius. At this point I'm beginning to feel like I'm back in the 5th grade again, and we obviously aren't communicating, so later.
Are you saying that you can tig with an AC only like my old Lincoln tombstone? I was always under the impression that you at least needed D C capability to scratch start tig.
Yes you need DC for scratch start Tig on carbon and stainless steels. You can Tig weld with an AC power source, but you would be using it for aluminum. In order to use an AC power source for Tig welding you need a separate high frequency unit to assist in arc starting and cleaning. (If the machine is not equiopped with it) The high frequency boxes were often used with AC power sources to allow welding of aluminum, or with AC-DC power sources, also to allow the Tig welding of aluminum when the machine was not equipped with high frequency. A lot of the newer machines are high frequency equipped when built. An example is my Miller Diversion 165, an AC-DC inverter power source. DC for welding carbon and stainless steel with high frequency for arc starting, and AC with continuous high frequency for welding aluminum. The old high frequency boxes.
One more option I havn't seen here yet is learning to weld with a torch. If you plan on welding alot of sheetmetal torch welding will teach you puddle control and rod feeding. If I had to choose between a scratch start tig and a torch I'd get the torch.
The reality and physics and chemistry of the situation is that you can not touch any two items together and not have some transfer of material, however minimal, major, or microscopic it maybe. That's a plain and simple cold hard fact. Btw- That also means your freshly ground tungsten will never be 100% pure. Then there's the practically of this situation. Tungsten contamination comes from a few major sources, dirt and oxidation on the parent metal or filler rod getting vaporized in the puddle. This actually contaminates the gas atmosphere surrounding the puddle and that gets bonded to the end of the electrode. And of course getting the tungsten in the puddle. You can't touch the filler rod with anything and not get a contaminant on it. It may be as minimal as to be on a molecular level but its there. Without the extreme heat of a molten puddle there is no contaminant deposited on the electrode that will alter the performance of the electrode or finished weld. If you get to within 0.011 or scratch it there will be no measurable contaminant unless you dip it in. ( don't believe it, hire a testing lab to measure the contaminant) So can you actually scratch the electrode and not get it dirty, NO. Can you touch it gloved or not and not get it dirty, no Can you grind it and not get it dirty , no. These questions fall into the same place as ... Can you piss in the ocean and not change the amount of water, no. Does it matter or make a difference - no. There's really no sense in insinuating stupidity, nincompoopery or hardheadedness. Any thread on the HAMB that involves welding gets heated and the garage hobbyists welding advisory board always shows its support.
HTP has some nice machines, and being an "inverter" supplied machine they don't make the house go dark when you are using it. Pricey, but small as a suitcase and they have great tech help. I have a 160 amp HTP Tig, ferrous metals only (my choice), with HF, foot pedal, etc. Works great, the only limitations are the user (me). One thing.....Mig can weld almost anything, dirty or clean. Tig welds clean metal and only clean metal, and you need to rethink your gaps because you are not using the "metal caulk gun" - type machine with a Tig. It is a great process for clean, strong welds. Good luck!
The nice thing about the scratch start machines are that they can be had second hand cheap. They're great machines and in the proper hands can really do some nice, intricate welding. The 2 major drawbacks are obvious; the possible contamination involved with tapping the electrode to start (even though I know you're really supposed to get it real close but in reality you don't want to wait), and the inability to fluctuate power as the weld dictates. One of the beauties of welding with a TIG is the ability to control heat with the foot pedal, which is especially important when welding pieces of varying thickness together, or with thin items, aluminum especially, when melting point can come and go very quickly. The scratch start machine is still excellent though, and a big step up from a MIG for many jobs, but still not as good as the full setup with the pedal. If you can score a decent one cheap, by all means do it. But if it's going to cost you, pass and wait for the real deal.
Miller inverters only use h/f for arc start after that in a/c mode as per alum there is no hf circuit involved in the arc at all.The advanced technology of inverters don't utilize h/f after arc is established.They have come a long way since the old h/f box used with an old a/c d/c tombstone. I weld with a dynasty 200dx nice smooth machine. Tig
Yes, correct , a slight old school type brain fart. The old AC machines used continuous high frequency for arc cleaning. The new inverters tailor the arc to be stronger on the positive side of the AC half cycle for superior arc cleaning action without continuous high frequency. Machines like Millers Dynasties even allow you adjust that percentage of balance from positive to negative in the arc for arc cleaning tailored to your needs. Another neat feature of the AC inverters is the fact that you can make precise welds in holes or corners using a sharpened to a point Ceriated tungsten. Unlike the old high frequency units that required a balled end zirconiated tungsten and when you tried to weld in a tight corner or hole the arc would often be hard to initiate and make the weld where you wanted it due to cross arcing to the material, or the sides of the hole.
Thanks guys, learned something new on the AC for aluminum, have torch and arc welded for yrs. Hope to have tig capability someday.
'Nincompoopery' that is a new technical tern that i just added to my jargon! Tig electrode contamination. What happens when the electrode is contaminated while welding steel? You have to throw everything away? Or does it just kinda fall apart when you are done? I am an experienced welder and -gasp - i admit to having a gob of goo on my tip once or twice.
Nincompoopery is a term that I picked up from one if my professors. He's been published and so has the word. Proper electrode prep of a contaminated (dipped and gob of goo) electrode is to break off about 1/2 inch and resharpen.
maybe this will help some..... I use a scratch start tig set up..it does OK.. I'll get a better set up 1 day..not a big need right now... but some good info on this site http://www.weldingtipsandtricks.com/tig-welding.html
The Jalopy Journal
