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Thread: TIG Welding

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    Pit Crew Decade Plus User MK1_Oz's Avatar

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    TIG Welding

    Experienced TIGgers I need your help........

    Recently bought this;

    https://www.welding.com.au/equipment...arc-200i-ac-dc

    I am trying to teach myself but may seek out a local course depending on how it goes (not well so far!!).

    I started out the first morning working with steel on DC. After some rubbish welds I did some not so rubbish ones. With more time I think I can easily iron out the issues and start having something presentable.

    That afternoon I moved to aluminium on AC with HF start. I quickly had some butt joints happening although there was alot of variation in appearance (prettyness, width, height) that I struggled to understand fully. I started to get a slight feel for balance, frequency and amps though. Then.....without changing any settings the thing just would not strike an arc. When I pressed the torch button it would spit out a quick arc then immediately stop and try again - spat at around 2Hz. I cleaned the material even more (dedicated stainless steel wire brush), re-ground the tungsten for the millionth time, checked settings etc but no dice. I gave up.

    This morning I have been at it again. I setup the machine from scratch, grabbed some fresh cleaned aluminium and viola it worked straight away (and quite reasonably.....maybe....see pic weld #1 below). I again welded away, changing some settings as I went so that I could see the results. Then after around about the same amount of welding the machine again started to not strike an arc!!! This time I can pin-point what I did before it 'failed'. The thin strips of aluminium were getting hot so I quenched it in some water then dried it off. I could not see water anywhere including in the butt joint area. Once I started welding again....no arc.

    I think it would be easy to say that the water quench was the cause but I have some doubts as I dried thoroughly. Maybe it caused a huge amount of oxidation build up?

    I have been struggling with keeping the tungsten out of the pool and with not pushing the filler rod into the tungsten. I am standing up which I am finding very uncomfortable for TIG (chair in design). I have re-ground the tungsten regularly on a brand new fine grinding wheel using the recommended technique.

    I have noticed that the tungsten goes blue alot although I think I have fixed that by having more post flow and holding the torch in place until it cools. I seem to get a BIG ball on the tungsten sometimes which from what I can tell is not really a requirement on an inverter machine. Other times the point stays to some degree.

    I don't want to jump down the path of this being a weld unit fault as I am new and don't know enough to go there. However, I am at a loss as to why the same thing happened after a similar duration and both times without any setting changes. The machine did not show either the voltage or over temp fault lights.

    This second time I was able to get an arc to strike and hold ONLY IF I turned the balance up to at least 70% however once started the arc seemed to have little power and was not creating a weld pool. I had not touched the amp control but it was like it was running at much lower amps. Could be oxide related but I have wire brushed the heck out of the material and cleaned it afterwards with carby cleaner and still no dice.

    I am at a loss and need suggestions. I realise you cannot fix things from the other side of the world but maybe somebody has seen this before of just knows what the cause is.

    My settings at time of failure;
    • Frequency 119
    • Pre-flow 0.5s
    • Initial Amps 95
    • Ramp Up Time 2.0s
    • Amps 95
    • Ramp Down Time 4.0s
    • Crater Amps 50
    • Post-flow 7.0s
    • Balance 66%
    • Cup Size #6
    • Gas Flow 6lpm
    • filler rod 2.3mm
    • tungsten: 2% ceriated 1.6mm
    • stock 3mm
    • gas 100% argon

    Not that I want to distract from my immediate issue but the welds in the pics are numbered in order. Ignore the area between 4 & 8 as they have been impacted by welds I ran on the back. An example of things changing when I don't understand why is that #1 and #2 I consider reasonable for a beginner but then the same settings results in #3 and #4 being flat and wide with #4 being very indented. My best guess is that the heat from the proceeding welds meant I should have lowered the amps for #3 and #4. There may have been some time passed by the time I got to #8 or maybe I changed the amps but it came out reasonable again. #1,2 & 8 had some weld material through the backside but not much in the way of full penetration (not sure if that is the goal with TIG on aluminium?).


    Last edited by MK1_Oz; 19-08-2018 at 02:45.
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    Pit Crew Decade Plus User MK1_Oz's Avatar

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    Re: TIG Welding

    I spent a few more hours on it.

    I walked into the shed and didn't clean or change a thing and it worked straight away. Then after a period of time the issue started again. My feeling is starting to be that the machine is causing the issue! At 77amps it has a 100% duty cycle and 15% at 200A so me welding around 90-110 I should have a high DC so that should not be the issue...
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    Re: TIG Welding

    I'm by no means a good welder...

    But the tungsten will ball up, that is normal. However if it is too much, it may suggest there is too much current going through too small a tungsten. ie go larger.

    I couldnt really do anything with a small 1.6mm, but have much better all round with the 2.4mm. But even then I've melted a few trying to weld some heavier stuff.

    Duty cycle will more relate to time spent welding at that before the unit trips out. ie if welding high current it will overload/trip sooner than much lower currents

    Also hot alloy will start and weld a lot easier and with much less current than cold metal...hence a foot pedal for control makes a good difference so you can easily reduce current as you weld and the metal gets hotter.

    But if yours is truly not striking an arc at all...maybe a different matter. Or maybe not clean, not enough current etc ?

    I'm sure you always want good penetration, however that's a fine line between blowing holes and not ! I know on my own pipes etc I do not get full penetration because I know if I tried, I'd just blow holes. On thicker material not so much of a concern I guess, on thinner then it would be more important, but on thinner it would happen more naturally anyway
    Depends how important strength actually is I guess.

    And not sure how important backpurging might be to assist with making the welds penetrate cleanly and properly.

    But definitely get a foot pedal. And just find what works for you. I know mine is probably all wrong, but I can join bits of metal together fairly weld most of the time now and I'm good with that.
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    Pit Crew Decade Plus User MK1_Oz's Avatar

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    Re: TIG Welding

    I spoke to the welding company I purchased it from and they are happy with my settings and feel there is something wrong. They want to see the welder to diagnose. Sods law it will run 100% for them - but then at least I know it was the organic component that failed...
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    Re: TIG Welding

    Thats bloody good customer service - most would blame the 'organic component' straight off! I know all machines are different but haven't managed to hit any thermal throttling / shut down even after some long use at moderately high ampages so would suspect the machine somehow.

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    Re: TIG Welding

    When on full whack, my machine will trip out now and again, usually towards the start of welding. Once some heat is in that same material it'll happily chug along though

    TBH, my hand would probably burn before I'd get enough time on the torch to trip any other overloads as it isnt a water cooled torch.

    At lower settings though it never trips
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    Pit Crew Decade Plus User MK1_Oz's Avatar

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    Re: TIG Welding

    Yeah this is a wierd one. The unit seems to be throttling the power although the fan does not run much (it also comes on randomly when the unit has been sat idling for ages). I am sure it is me but cleaning the stock well and regrinding the tungsten isn't fixing it so I find it hard to believe it is contamination related. When regrinding a contaminated tungsten, how much gets removed? I have been grinding it down just enough to see nice shiney metal. Maybe I need to go harder?
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    Re: TIG Welding

    The foot pedal arrived today. Much much easier from an ergonomics point of view. I can hold the torch how I like and be comfortable.

    When I plugged the pedal in it still allowed me to select 2T or 4T. Which should I go for. I think it was explained previously that the pedal effectively takes care of the 4T stuff so I assume 2T.

    I watched a video today explaining contamination and he said that once the tungsten gets contaminated that it cannot be cleaned up with grinding alone. He said to snap the end of the tungsten off then resharpen. I have been doing that today and it seems a little better. However, I am going through tungsten like there is no tomorrow!
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    Re: TIG Welding

    Equally there are many videos of people welding with unclean metal, unclean tungstens and they can weld just fine.....so no, you dont need to go nuts with that

    IMO as long as the tungsten is clean, with no lumps of alloy on it ( happens me a lot lol ) then it will be capable of good welds

    I just use a flap wheel in a grinder and try and hold the tungsten at 90deg to the wheel so it is grinding almost length ways towards the tip of the tungsten, grinding a small angle onto the tip.
    With Alloy it will ball up anyway, so wont matter about a point or anything.

    But the flap wheel will easily clean the tungsten to bare metal and it will weld perfectly fine. Perhaps on smaller 1.6mm it wont as the base material is thinner, but for me with the 2.4's I've had no issue.
    Last edited by stevieturbo; 21-08-2018 at 13:03.
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    Re: TIG Welding

    Hi Mk1_Oz,

    I'm not a fabricator by any means, just a fella who has spent the past 12 months messing with a tig welder on all sorts of various ferrous and non ferrous metals. I'm an engineer by trade and am fascinated by the metallurgical side of it.

    I was in your exact shoes, and i can perhaps share a bit.

    I found doing a course (i did it 1-2 nights a week at Swinburne tafe for 6 months) didnt give me the hand skills as much as it did teach me the principles behind it. With a solid understanding of how tig welding in both DC and AC works, how the settings on your welder specifically affect that pretty arc and the metal it touches is invaluable...as it lets you very quickly troubleshoot on your own without guesswork.

    Jody Collier (Weldingtips and tricks) as well as Bob Moffat (Weld.com) on youtube are awesome sources of info too.

    The hand to eye co-ordination comes only with practice, and its like handwriting....the skill just creeps up on you unknowingly as you put more hours into it. Buying a large F sized bottle was the best thing I'd done. I did burn through it in about 7 months of hobby welding.

    The High Frequency start can work sporadically if the tungsten or metal is dirty. Basically the circuit is failing to be completed and it could even be the ground clamp having bad contact and not being able to conduct (for whatever reason).
    Aluminium I have found (and anyone please correct me), to be prone to arcing. The best thing i did was make a simple "3rd Hand" out of some copper rod and i tig-brazed some silicone bronze filler material into a blob on each of its contact points. I basically use this all the time and lean it against anything i am welding to ensure i have a good ground (at first i kept forgetting to, but it is second nature to use it now).

    I figure since its a 15 amp machine, you will probably do more sheet metal stuff, like tanks and panels etc. I didnt realize how important it was especially with straight edges and flat sheet, to try minimize heat input to stop warping. If you're at the scrap metal dealer, get a few blocks of copper (I've got 2 brick sized pieces) that you can use as heat sinks. Park them on the metal as close as practical (i get mine within 5mm of the edge of my bead if possible) It helps....so much in preventing warping. Welding stainless, also means you can do so with a smaller cup and less gas flow as it acts as a dam for the argon just long enough for the metal to cool to a point that it wont oxidize too much.

    I watched Jodie Collier do a vid and he mentioned having a rod of filler and a glove on the coffee table so that you can just fiddle around with getting the feeding motion downpat whilst watching TV......my girlfriend thought i was stupid for doing it....but you'd be amazed how much it helps. I did it with a garden glove. Especially with aluminium, as you basically do everything in an exaggerated manner when welding ally.
    Being able to get as many motions you do whilst welding out of your mind and into muscle memory, lets you focus 100% on the puddle and it really shows.

    Cleanliness is another huuuuge thing I found. You see CASA or other Aerospace certified guys doing x-ray welds that are shit hot...and then look at their workspaces......its cleaner than a kitchen bench. Before i weld, I squirt a little acetone on a clean rag and wipe everything from my bench to the metal and the tungsten down. Just doing that alone will rid you of inclusions/contaminants and create a clean finished weld.
    A 5L bottle of acetone is $25 from a solvent company in Sydney they deliver interstate for peanuts.

    Yes I know many folks who dont care too much about it. But, best thing is to try a few welds on immaculate metal, and on some slightly dirty metal....and make the call yourself. If you're going through all the time (probably quite a few hours) of cutting, grinding/linishing, filing and fitting up pieces.......20 seconds of wiping with acetone is rather worth it.


    Anyway, yeah, post some more pics of projects you choose to weld up! I'm sure that I'm not the only fella who'd love to see!




    Cheers,
    Siggy
    Last edited by Schaloupka; 22-08-2018 at 13:16. Reason: incomplete post

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    Re: TIG Welding

    Cheers Siggy, good info.

    I can see this will be a long process. Having the pedal has already helped although now I am having to work out just how much to push and back off the pedal.

    My welding table is very dirty as it is also my gearbox rebuilding table, bending table, design table, electrical assembly table...you get the picture. I started to use acetone the last time I TIG'd.
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    Re: TIG Welding

    Fuck..you should see the state of the welding table I made....in fact...I can barely even see it lol it's covered in that much junk.

    But good earthing is another very important aspect. It's all very well earthing a table and setting the workpiece on it, but with the currents involved often that is not good enough. Earthing directly to the workpiece is best.
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    Re: TIG Welding

    Quote Originally Posted by stevieturbo View Post
    Fuck..you should see the state of the welding table I made....in fact...I can barely even see it lol it's covered in that much junk.

    But good earthing is another very important aspect. It's all very well earthing a table and setting the workpiece on it, but with the currents involved often that is not good enough. Earthing directly to the workpiece is best.
    Haha StevieTurbo,

    That's usually the case aye. But it really does depend on a few things like if the weld is structural and what the metals being welded are that sways your ratio of how much time preparing to actual weld time you're willing to allocate.

    When i finished high school, i trained in an aircraft hangar and machinist shop and later spent a few years working in a composites workshop after i finished uni. All these places stressed cleanliness, and so the habit just stuck.
    The amount of times i wipe the kitchen benchtops drives my missus nuts...LOL!

    To each their own. But yep, as a minimum you do want a clean tungsten, some filler rod thats not oxidized and enough gas flow and a foot square sized area thats clean around your work. Use the Pareto rule of 80% result for 20% effort

    Earthing to the piece is fine if its large, but for smaller things like tanks and brackets you get an equally good earth by having a bit of copper (a third hand that takes 20 minutes to make) leaning against your work.

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    Re: TIG Welding

    For thinner lighter stuff, earthing via the table etc does work fine....not always so successful where more current is required.

    And I've also burnt some thin alloy parts from not having a totally secure earth where there was arcing at the earth point. I'm sure I even burnt a hole through a thin pipe one time when I had the earth clamp affixed to the pipe !

    Point is...until you know you can do good repeatable welds...ensuring a good earth is important ( as is cleanliness I fully agree )
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