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  1. #1
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    TIG Amperage Question

    I am just getting started with my TIG practice and I am hoping to churn out a practice frame in the next few weeks. I have been practicing on test joints consisting of .049" thick tubing, but I have also been experimenting with welding 1/8 " tabs onto sections of tube as well to try and get a feel for how joining two pieces with a large difference in thickness together.

    I know the rule of thumb for DC is 1 Amp for every .001" of material thickness that is being welded, but I was wondering what amperage to use as a starting point when welding two sections together that have very different thicknesses. Specifically, at the bottom bracket and headtube joints, shock mount tabs etc. Is the thinner material the determining factor in these cases or is it the thicker section? I reckon that the sweet spot may be somewhere in-between the amperages that would be best for joining each respective thickness, is this about right?

    Also, I take it that it is a good idea to focus the arc towards the thicker piece's edge in the weld root?

    Thanks!

  2. #2
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    1) are you using pulse?
    2) what's your peak time?
    3 what's your background %?
    There's lots of settings that affect the amount of heat you put in a joint.
    Yes use more on the thicker section.
    I can say more when I know more.
    Kind of like the classic saying" You don't know what you don't know"
    cheers
    andy walker
    Walker Bicycle Company | | Walker Bicycle Company
    Flickr: afwalker's Photostream

  3. #3
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    What machine are you using? It won't hurt to have the amperage on the high side and be light on the pedal to compensate. You want to have enough amps to immediately establish your puddle and then back it down from there. When welding two different thicknesses I aim the electrode slightly toward the thicker piece. Post up some practice pics and I'm sure you will get good advice.

  4. #4
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    The best advice I can give in as few words as possible, (hard for me)
    is to turn up the amps to say...80, but it really doesn't matter. Just have it be hotter than you need. No pulse, just straight amps.

    Learn to use the foot pedal to control the heat input with your tacks, and then your welds. Tacking can be more difficult than it seems like it should be. One really good thing to practice is tack without filler rod. I still do this where I'll "fixture" the tubes together with my left hand and tack with my right. This will quickly make you learn to 1) get tight miters, 2) control the heat input, and 3) slightly point the tungsten at the thicker non-mitered tube first to start the puddle and drag it over to the mitered tube to join them.

    Then make something silly with all the segments of tubing like below.TIG Amperage Question-oneinchtube_monster1.jpg

  5. #5
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    I am using a Miller Dynasty 200
    17F torch
    no pulse DC
    15-20 CFH
    #8 cup
    1/16 electrode
    1/16 ER70-S2 Filler

    etc.

    I will try and snap some pictures for you guys.

    I also have access to a Miller Syncrowave production machine, but I figured I should keep it simple so I have been using the Dynasty so far.

    I also just picked up one of those CK Pyrex gas lens kits so I may try that out soon here.

    Current strategy is to give the machine about 10% more amps than I figure is optimal and use the foot pedal to throttle the heat after I get going. I am still in the process of feeling out my heat and feed speed on various thicknesses. The only real welding experience I have prior to this is stick so I have a lot of practice ahead.

    Currently, I think that my main issues are holding a tight arc without submerging the tungsten and letting the end of the filler rod wander out of the gas shield while traversing.

  6. #6
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    2-4 amps per thou, use the pedal. Starting out without pulse is a good plan.
    You have to set your peak time and background % to something.
    I like lower but set my main amps higher.
    Name:  12674748383_c6320a4329_m.jpg
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    Here's another thread just recently discussing this, maybe you saw it already: Basic Tig
    Notice, nobody actually gave you all the numbers. Folks are kindy fussy about their skills that took a long time to perfect maybe. They talk about all kinds of main amps, but not all the modifying settings.
    cheers
    andy walker
    Walker Bicycle Company | | Walker Bicycle Company
    Flickr: afwalker's Photostream

  7. #7
    RCP Fabrication
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    You are on the right track, lots of practice. Ignore pulse for now. Get rid of the 1/16" filler, I'm not going to say its impossible to weld frames with 1/16" filler..... but it's pretty much impossible to do it well. I use .045, a lot of people like .035 also. Straight DC I set my panel amps at around 75.

  8. #8
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    Even if the tubing I am using right now is 0.049"? What if I am welding some dropouts on that are made from 3/16 " plate? Do you think that the big rod cools the puddle too much? I have some .045 rod I will try some of that.

  9. #9
    RCP Fabrication
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    I don't even consider 1/16" filler until I am welding 1/8" to 1/8" or thicker.

  10. #10
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    Been practicing myself. I do have some previous experience, but never on anything as thin as 035. Once I switched from 1/8" plate to 035 tubing, even the 045 filler was tough for me to use and going down to 035 made things easier. I've been using mig wire (ER70s6) because the lws were all out of 045 or 035. Kind of a pain to straighten, but I was itching to get started.

  11. #11
    AZ
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    If you have a wire feed machine you can use the wire straightener in it to straighten your wire, just pull the wire through and cut it to length.

  12. #12
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    Can you do that with removing the wire that's in it?

  13. #13
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    Quote Originally Posted by ktm520 View Post
    Can you do that with removing the wire that's in it?

    The wire you wish to use needs to be loaded in the machine, chances are that it already has 035 or 045 in it I'd bet.

  14. #14
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    Quote Originally Posted by heavy metal View Post
    Do you think that the big rod cools the puddle too much?
    The specific answer to this is yes, and that is an insight that has taken a long time to sink in for me. I'm more of a doer than a reader/studier, and I'd never seen that aspect of TIG filleting discussed before. I just used what the LWS had, which was .0625. It never occurred to me to grab some of the .030 leftovers from my MIG and give that a whirl. I used some to TIG something the other day, and although it was a bit small for the size of fillet I was doing (had to stuff a LOT in there), it worked well. (BLINK... light comes on)
    Most people ply the Well Trodden Path. A few seek a different way, and leave a Trail behind.
    - John Hajny, a.k.a. TrailMaker

  15. #15
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    Every machine is different and welding styles will have more of a variance than that. What works for me on your machine might not work for you (I weld with a heavy foot). So in reality nobody can answer that question for you.

    Personally my 200 amp machine is set at either 125 amps or 200. Anything in between and I'll use the foot pedal.

  16. #16
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    I am mostly self taught at this TIG thing and have a long way to go. This forum has been a huge help. As a hobby builder I generally only spend a few hours in the shop each week.

    The basics as discussed in this and are always super useful. I think I have a generally understanding of the theory but the practice of actual welding is something that will simply take time to acquire.

    I am interested in some more feedback. I am looking for tips and am always interested in the discussion of what the visual signs of a good weld are.

    These were done on scrap tubing using a Miller 150 STH with pulse at 65 amps using 035 rod and 1/16 tungsten.





    Mark Farnsworth, Raleigh, NC
    http://farnsworthbikes.com

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