Announcement

Collapse
No announcement yet.

Tig welder and hi-voltage

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Tig welder and hi-voltage

    I understand that Tig welders use high frequency and high voltage to start the arc. What's to keep the welder from getting zapped and also does the high voltage cut out once the arc has started?

    Albert

  • #2
    The more expensive the machine, the more options are available.
    TIG welding can be done with nothing more than a DC machine and a TIG torch with appropriat shielding gas. The acr is started by the scratch start method, and the heat is varied somewhat by the torch position. This is similar to Oxy/ Acetylene welding, but concentrates less heat in weld area.
    As you add options, high frequency makes starting arc simpler, and increases materials you can weld, aluminum for instance. The high freq for establishing arc switches off after arc is started. Higher voltages, and voltage control by means of foot pedal or sliding switch give closer control of weld heat. Arc stabilization and probably more things than I am aware of are added as the price increases.
    Most welders survive the experience, so appropriate measures are taken to protect them.
    Jim H.

    Comment


    • #3
      Welding heat is based on current, not voltage. Even high voltage is low in a welder, on the order of 20-30. High frequency arc starting uses high voltage, high frequency, but very low voltage (like millivolts). It's really hard to get zapped by a welder, more likely to get burned.

      [This message has been edited by bdarin (edited 05-25-2002).]

      Comment


      • #4
        <font face="Verdana, Arial" size="2">Originally posted by bdarin:
        Welding heat is based on current, not voltage. Even high voltage is low in a welder, on the order of 20-30. High frequency arc starting uses high voltage, high frequency, but very low voltage (like millivolts). It's really hard to get zapped by a welder, more likely to get burned.
        .]
        </font>
        Bdarin,
        I think you meant to say "very low amperage ( like milliamps )"
        Tigs do use high frequency arcs.
        When welding aluminium on AC, the high frequency arc is on all the while to stop the alloy sticking to the tungsten.
        On DC for steel or stainless the HF ceases after a few seconds, just enough for you to strike the arc up.
        You can get a jolt off it but it's like a spark plug lead, all jump, no load.

        One tip and you will laugh at this. I had about 6 years MIG welding on steel before I bought my first TIG. I have secondary flow misers on the gas bottles to conserve gas. My usual method of start on a MIG up is, switch the machine on, turn the wire feed down to zero, hit the trigger and adjust the gas flow by ear to get a nice flow. Then set amps and wire and start welding.
        So I bought the TIG, switched on, hit the trigger to adjust gas flow whilst listening. And this bloody great HF spark jumped from the gun to my ear lobe!!!!
        What a twonk!!! It really made me jump. I was hopping about the shop shouting "O Golly Gosh" and such thinks like that but I still have to smile about this years later.

        John S.

        .

        Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



        Comment


        • #5
          John Far be it from me to call anyone a liar but I don't believe you said the words (oh golly gosh at all)also john I bought the mig we talked about earlier unfortunately when I opened up the box it had no wire or gas inside so will have to go back next week for some as it was a good deal supposed to come ready to use.cant wait to try it.AlistairP.s That guy has still got the syncro.
          Please excuse my typing as I have a form of parkinsons disease

          Comment


          • #6
            John Stevenson:
            I have always used actual flowmeters on the shielding gas - they are calibrated in L/min. They prevent an enormous waste of shielding gas (important with expensive Helium and Argon) and give more consistant welds.

            The story about welding your ear is damn funny! I think Alistair is right - sailors were blushing that day!

            Comment


            • #7
              I'm still confused. Can you or can you not get a mild electrical shock with TIG if the electrode is directed at you rather than at the grounded metal? John, I don't know if you're pulling my leg with your story (with your dry sense of humour, I'm afraid to second guess), so I would like some clarification.

              Albert

              Comment


              • #8
                Albert,
                Yes you can get a shock if you touch the tungsten whilst welding. This is very hard to do as the tungsten is shielded by a ceramic tip.
                In normal welding it's virtually impossible.
                The story is true, not a make up. I still have to smile at my stupidity all these years later as I knew how they worked.
                I can honestly say this is the only time I have ever got a belt off this machine in about 10 years.

                John S.
                .

                Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                Comment


                • #9
                  Albert
                  I have had shocks from my car batteries!

                  Welders are pretty safe providing you disconnect electronic gear attached to the equipment you are welding - otherwise you can cook them. Just like frying the injection computer on a car by jump starting another car the wrong way...

                  Comment


                  • #10
                    I have a portable Esab TIG unit with HF start, and so far I've been zapped in 2 different ways. (1) Forget to connect the ground clamp and touch the work while trying to start an arc. (Imagine Homer Simpson's "Doh!") (2) Wrapping the hot cable around my body as a strain relief created enough capacitive coupling to give me a tingle when I leaned on the work.
                    I would not be surprised to get a tickle by holding the filler rod in a bare hand, so I always use a dry leather glove and have never had any such problems.
                    Folks with a pacemaker or implantable cardioverter defibrillator (ICD) need to be EXTRA careful with all arc welders and should consult with their physician.

                    Comment


                    • #11
                      I think the pacemaker dangers are overated. have no ideas about the defibrilators. I have had pacemaker since 1979. Only time I ever had it trigger from elecromagantic field (excepting when being tested) was when I was standing beside an induction furnace, we had a melted cone of aluminum that looked like the scoop of ice cream you use in a ice cream cone, but it was about two feet across. heat was stricktly from induction coil, the cone squirmed and boiled. lots of power and I was very near. I could feel that one and had to back off. no one else noticed, a very minor thing. Intermedics says don't even ride a lawn mower (in their book that you get with a pace maker). The local rep says there is no documented case where the pace maker has been afffected. I can make it trip by holding a DC welding lead on it and stiking an arc. so i guess you dont want to lay on the cable, nor as mentioned above, wrap it around you.
                      BTW, never had a heart attack, heart muscle is in good shape.
                      Steve

                      Comment


                      • #12
                        Ralph hit on a good point,the filler rod!I have tig welded for years and often if the part being welded is extra small I will hold the filler bare handed and have no problems.However if the filler rod should happen to make ground with some other part of the setup you will get popped but nothing fatal.Either way as long as you don't become part of the circut your ok but man 40 volts dc is uncomfortable!
                        I just need one more tool,just one!

                        Comment


                        • #13
                          John-

                          That reminded me of my high school shop teacher. He used to demonstrate the HF arc from the TIG welder by jumping it to his thumbnail. After being very certain he wasn't grounded through.

                          I wonder if he could have lit a lightblub like Tesla did while doing that. Pretty much the same thing.

                          Kevin

                          Comment


                          • #14
                            hold the tip to a flourescent bulb. it should light. you hold the middle of the bulb or even near the end on the glass. I would say all will light but I have not tested all. Good way to win a beer bet where you claim you dont need a return wire.

                            Comment


                            • #15
                              Warning: Modern welders often operate up in the 50v range. Care should always be taken when handling a gun/stinger - OSHA has safety guidlines for safe welding and they should be followed. The voltage and current is high enough to kill you and it does kill many people in Canada and the US every year.

                              Please be carefull - Safety First!

                              Comment

                              Working...
                              X