Scratch starting TIG welding

[Camphor]

Hello. I have TIG welding torch that I hook up to my stick welder, what I need to know is how far do I set the tungston rod past the end of the cup. I have the torch hook to the negetive side of the welder, postive goes to the work, any help would be great. camphor

[Charlotte]

The distance and the shape of the tip are determined by the application. I recommend to everyone buying and reading The Procedure Handbook of Arc Welding, published by The Lincoln Electric Co. It is available direct from the company or on line from Amazon and Google.

That said: Tell us a little more and some expert will tell you what you need to do with your equipment.

[Camphor]

Hi Charlotte, I am making a drill press table support that slides up and down the drill press collumn, making the piece from 3" sch 40 black iron pipe,needed to shim the inside dia., of the pipe and want to TIG weld the shim in place,though this would be a good place to start my learning of TIG welding. camphor

[Charlotte]

Camphor,
I understand that you want to weld a shim inside a piece of schedule 40 3" pipe.

What is the shim made of? How thick is it? What amperage, type of tig unit, kind of electrode and so forth.
I learned in the school of mostly self taught also so we'll have to wait for one of the experts to answer.
Welcome to IforgeIron, btw If you go to the top of the page and add some location information in USER CP it would help us help you in the future.

[Camphor]

HI the shim is mild steel 3/16"x 1"- 85 amps /125amps- TIG torch is model 17v weldcraft- using straight argon gas 20/25 cfm -torch electrod is 2%, I am using my Miller stick welding machine,I tried to weld with this setup once before had the torch hooked to positive side on DC should have had torch hooked to negetive side of DC . does this sound correct. camphor

Camphor,
I understand that you want to weld a shim inside a piece of schedule 40 3" pipe.

What is the shim made of? How thick is it? What amperage, type of tig unit, kind of electrode and so forth.
I learned in the school of mostly self taught also so we'll have to wait for one of the experts to answer.
Welcome to IforgeIron, btw If you go to the top of the page and add some location information in USER CP it would help us help you in the future.

[arftist]

Hi, The diameter of the cup and the diameter of the electrode determine the length of the stickout. With a big cup and big electrode, you can have more stickout. In general the tungsten should stickout about 1/2 the diameter of the cup or less.

[peacock]

A good rule of thumb for stick out is one diameter of the electrode. You will need a point with a taper about 1 1/2 to 2 times the diameter of the electrode with the grinder marks running lenghtwise of the electrode. A number 5 cup would be a good place to start about 20 cf on the flow meter. I hope your torch has a valve on it, it is much easier than turning the bottle on and off. Tungsten life will be much longer if you use a copper scratch plate and pull off onto your work. You can do this but I would sure miss my foot control.
Phil

[Nakedanvil - Grant Sarver]

Good rules of thumb, guys. You will want to vary that a little as you oten want more stick-out on fillet welds than on flat. Remember, every time you "poison" the tungsten you'll need to grind ALL THE FILLER MATERIAL OFF before continuing.

[arftist]

For welding aluminum, I use much less stickout, on the order of 1/2-1 diameter of the tungsten, but since the thread was about scratch start, I didn't mention that.

[meinhoutexas]

on alum do not put a point on the tungsten you want a ball and i would strongly encourage you to play with you setup before you try to make or weld in place anything. would hate to have to scrap something when your arc wanders around .

[RcRacer]

on alum do not put a point on the tungsten you want a ball and i would strongly encourage you to play with you setup before you try to make or weld in place anything. would hate to have to scrap something when your arc wanders around .

That may be true ( balling your tungsten ) for a transformer type welder but for inverters, you can/should put a point on the tungsten for aluminum for better arc control.

[peacock]

use a ball for ac current a point for dc. never seen a inverter with AC output.
Phil

Edited August 24, 2009 by peacock

[RcRacer]

use a ball for ac current a point for dc. never seen a inverter with AC output.
Phil

I don't want to hijack the original post which was in reference to stick out and mild steel but my machine ( a Thermal Arc 185tsw ) or any of the new inverters like the Miller Dynasty have square wave output which is AC. The difference is that the frequency and the proportion of negative and positive output can be controlled. With square wave type AC, you need to sharpen the tungsten not ball it.

Now for the the original question, I follow the general rule of no more stick out than half the diameter of the cup. You can get away with a little more in t joints especially when using a gas lens. As long as you have gas coverage and no contamination, the stick out you are using is OK IMO.

[Nakedanvil - Grant Sarver]

peacock: You must be thinking of something else. The function of an inverter is to convert DC to AC.

[peacock]

original post said stick welder. Miller inverter welders listed as stick welder in 2009 cat. DC out put only. however Miller welders listed as Tig/ stick have both AC/DC. Grant I respect your knowledge but all my inverter welders have ac input dc out put. am I confused? please help me out. Phil

[arftist]

Yes, definitely confused. My 185 GTS has AC. My V-PRO-350 is DC only though, if that helps.

[Nakedanvil - Grant Sarver]

Well, we may need some more expert input. Technically, an inverter converts DC to AC. How it functions in a DC out welder might be something else. Strictly speaking DC does not have a sine wave at all. In practice it all starts as AC then is rectified to DC which allows it to be manipulated with an inverter in a number of ways, on/off time, frequency and to create a pulsed DC out too. So, I too am confused.

[Dragons lair]

The newer light weights may give you AC or DC but will they run all day long at 300amps? My antique will. Yeh its great to have a welder weighing 60lbs plug in anywhere. Ill stick with my 900lb+ weld anything i want. 1.5-400 amp AC DC+ DC- Hf start or Cont.
Ken

[RcRacer]

I think that we are all getting hung up on the literal definition of an inverter. Inverter welders are primarily switching DC to DC power supplies. The circuitry converts the incoming AC to a high frequency, eliminating the need for a large transformer resulting in a lighter power supply with a lower incoming power requirement. The inverter portion creates an AC output that can be adjusted for frequency and an adjustable ratio of negative / positive portions of the AC cycle. The waveform is a square wave but it is AC. The switching DC power supply and the inverter are combined in the more sophisticated welders. Most weldors refer to these types of welders as "inverter" welders.

[Nakedanvil - Grant Sarver]

From Lincoln:

Transformers are relatively inefficient operating at 50 or 60 Hertz. A lot of heat is generated in the transformer, and the transformer must be relatively large and heavy. A significant part of the power cost goes into heating the transformer and the surrounding air. Most such welding power supplies weigh around 400 pounds and have a shape something like a 32 inch cube. Additionally, if 60 Hertz is used, control signals are limited to being issued at no more than 120 per second, so it's impossible to pulse the welding current any faster than this.

In inverter controlled power supplies, the same incoming 60 Hertz power is used. However, instead of being fed directly into a transformer, it is first rectified to 60 Hertz DC. Then it is fed into the inverter section of the power supply where it is switched on and off by solid state switches at frequencies as high as 20,000 Hertz. This pulsed, high voltage , high frequency DC is then fed to the main power transformer, where it is transformed into low voltage 20,000 Hertz DC suitable for welding. Finally it is put through a filtering and rectifying circuit . Output control is performed by solid state controls which modulate the switching rate of the switching transistors.

What advantages does this new inverter controlled design offer? First, the main power transformer, which operates at 20,000Hertz is vastly more efficient than 60Hertz transformers, which means it can be much smaller. Remember, transformer - based machines typically weigh 400 pounds plus and are a 32 inch cube. The accompanying photo shows the Lincoln line of inverter - based gas tungsten arc welding (GTAW) power supplies. The machine in the center, the V205, weighs 33 pounds and is 9 inches wide, 19 inches deep and 15 inches high. The other two machines are DC only inverters and are even lighter and smaller. So there is a huge advantage in weight and portability in favor of the inverter - based machines.

So, I stand corrected.

Edited August 25, 2009 by nakedanvil

[arftist]

Yep there is a lot to be said for inverters. For the shop only guy or gal they don't hold much apeal unless you want to save a lot of money on your electric bill. But for those who work in the feild it they are a godsend. I remember shipping a 500# synrowave to a jobsite, rigging it inside, having the sparky wire it up, having to move it around the building, all to install some aluminum handrails. These days, I can walk in with my 44# inverter that actualy welds BETTER than my 250 amp synchrowave, set it on a stair tread, plug it into any 220 oulet of thirty amps or better and melt aluminum all day. Or burn 7018 all day. Or if it is a huge job, I can bring my 350 amp, 66# inverter and run 1/16th wire out of a suitcase mig. Also available are TIG/stick machines that weigh 12#, run on 110 and are smaller than a toaster, with a shoulder strap you can climb a ladder and weld. Too useful to ignore at this point.

[peacock]

Grant thanks for the info. I really appreciate everyones help. I was still wondering about pointed tungsten on AC. What I found out is something like this AC out put from an inverter based machine is not really AC at all but 2 inverter generated DC circuits 1 with a positive polarity the other with a negative polarity turned on and off to mimick an AC out put. thus the need for a point, it is really DC. I hope I have understood and relayed all of this correctly. If I have messed this up I'm sorry and still may need help. This thread has strayed along way from the original post but I for one have learned alot thanks.
Phil

[Nakedanvil - Grant Sarver]

peacock: Well I appreciate when someone clocks me up along side the head, if I'm getting too "know-it-all" like. Why, back in my day an inverter was just an inverter............

Always things to learn. I even knew a lot of it as it applies to my induction forges. Didn't even relate it to welders.

[peacock]

Hey Grant the first I knew about inverters was this little box I use to install under a car hood to change the alternater out put to AC so we could run a drill motor. We are pretty lucky to have access to all this info at the end of our fingers. I hope to own one of your induction heaters soon. I think it would be perfect at demos, no noise, no more burned up iron while answering a long question, much cheaper to operate.
Phil

[Nakedanvil - Grant Sarver]

Pointy tungsten for aluminum? Back in my day we dint need no pointy tungsten, we had balls (on the ends of our tungsten). Why my ol' Miller Gold Star was good enough then and could even anchor the Queen Mary in a pinch. Prolly cost a whole lot less per pound too. Ah, ya gotta love modern technology though. Sa...weet!