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Thread: TIG Welding Galvanized Steel
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4th May 2015, 10:13 PM #31Diamond Member
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True, but only kind of. A proper TIG machine is *strictly* constant current, no matter the arc length. You set it to 70A and it won't go above that. Stick inverters are also constant-current machines (MIG is constant-voltage) but typically have "added features" such as "arc force" or "anti-stick" - what they do is as the arc gets shorter, they allow the current to increase above what's on the dial, which gives more "dig" or "arc-force" and can also prevent the rod sticking to the work.
Hence you can get little stick inverter machines with a switch on them for TIG - it actually changes the behaviour of the current supplied to the electrode/torch.
All that said, if you can TIG OK with the machine you have, it's not really a problem.
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4th May 2015, 10:20 PM #32Golden Member
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Gazza, you might have been pushing the limits of the 1.6mm tungsten. I've seen some charts that put their upper limit in that 70A range. As it got blunter, arc penetration increased and pop! a hole.
Actually, that's for the 2% lanthanated that I use. I'm not sure what you use but presumably they fall in similar ranges.
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4th May 2015, 10:26 PM #33Golden Member
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The blob was more likely molten tungsten (too much amperage for the size of tungsten) or the zinc condensing on the tip. The crap all over the nozzle is probably a mixture of paint, rust, oil and whatever else was left on those filthy bits of metal you're sticking together . Probably got a few blobs of metal stuck up in there too?
It might also be oxidised tungsten - like might happen if you forget to turn on the argon or the wind is blowing the gas away. The fact that you're burning up tungsten tends to indicate this might be happening.
Truth be told, you're doing pretty well to get any sort of weld given you're outside, waiting for a breeze to blow away the fumes and persevering with a #5 cup.
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4th May 2015, 10:42 PM #34Most Valued Member
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just took a couple pics of the welds cleaned up, i was grinding than wire brushing than re welding i think i should have wire brushed the flux off the old mig welds before grinding but i never thought of that possibly the grinder is burring the flux? or maybe im dreaming lol
while i was out the back i noticed a a lot of crap on the surface of the metal that i never seen during day light hours so i do agree i will do more cleaning
thanks for the heads up on the 1.6 tungsten's limits i thought it must have been my machine
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4th May 2015, 10:45 PM #35Most Valued Member
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Something strange and very wrong is happening here.
A 1.6 Tungsten should handle 70A DC easily and be effectively non consumable i.e. not burn up at all. You are running the tungsten on the negative side aren't you?
Post a photo of your tungsten before and after welding if you can. I am uneasy about the whole set up as something is clearly amiss, your 140A welder should be almost maxed out on 3mm amperage wise 120-130A would be a rough estimate, yet you are running only 70 odd, which suggests to me that you are welding r e a l l y s l o w l y, which is not ideal for several reasons, massive distortion and large heat affected zone being some of the more common ones. It would be damn near unheard of to blow holes in 2.5 or 3mm material with a tig at 70A in the normal way.
I hope you don't take offence, but I strongly suspect that with your eyesight issues, you are welding really slowly as it is easier for you to track the weld and follow the joint. Your only real way forward is to address your eyesight issues as best you can. Quality tig welding requires a higher standard of eyesight than just about any other process I can think of, as you are constantly trying to maintain a short arc while feeding filler wire into a molten puddle and follow the joint.
I really want you to achieve in your endeavours as a welder, but I do feel you are heading off on a difficult course and are making life harder for yourself than it needs to be.
I have two final thoughts on the situation as it stands. Tig would be at the bottom of my list of processes for trailer building, particularly outside and that if you can't see, you can't weld.
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4th May 2015, 11:14 PM #36Most Valued Member
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im actually running the torch on the - and earth on the + im always confused with polarity but just checking google i think have my polarity in in normal mode that would explain why i never seen the over temp light come on but does it explain any of my other issues?
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5th May 2015, 09:29 AM #37Golden Member
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You have it right Gazza, for TiG the torch/tungsten should be on the -ve and the earth clamp connected to +ve.
If they were reversed then yes, that would explain a few things, but I don't think that's the problem in this case.
Fully agree with Karl's last post... I've got two helmets, one is an older one that I haven't got a magnifying lens in, my new one which I use all the time does. For some reason, I picked up my old helmet the other day and all sorts of issues - sticking the tungsten, long arc, etc. My eyesight clearly is not what it was only a couple of years ago. I fully recommend getting a 'cheater' lens. If your helmet wont accept one, just gaffa tape it in place.
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5th May 2015, 10:38 AM #38Golden Member
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You can't quite see but in the first photo I posted, that's a 2.4mm tungsten and it's still shiny silver and not dulled at all. OK, it's well within it's safe range and all but it stays that way indefinitely. I agree with Karl, if there's something going wrong with your tungsten you need to know why. I still think you need to do a lot more cleaning of the metal as Mick said. Flap disc on a grinder is my first tool of choice.
For me it's at the top.
- I love tig
- it's good for all positions
- it's clean
- I don't have an issue outside, typically with #5 or #6 cups, a gas saver lens and 6-7L/m
But I'm just having fun, not a pro. If I were a pro it might be mig. One thing's for sure, I don't want to build another trailer with stick.
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5th May 2015, 10:51 AM #39Diamond Member
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I'll say this a 3rd time - he's not using a "real" TIG welder. As the arc shortens, the welder will boost the current *way* above 70A, so he could easily be welding with 120A or more. I've measured my little BOC stick inverter will putting out 160A as the arc shortens even though the dial only goes up to 130A.
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5th May 2015, 01:51 PM #40Most Valued Member
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ok guys i picked up some Acetone and new TIG rods, i looked up howto reuse my other rods and people were saying to use a scotch brite pad so i did maybe that is my contamination? will find out shortly
rusty i dont think its my machine as with the 2.4mm tungsten i can easily control the puddle its just the 1.6mm tungsten i must also add these two tungstens came with my welder and my welder was second hand but pretty much brand new the kid didnt know how to TIG weld so gave it up very quickly and on sold the machine, both tungstens that came with the machine were red tipped
ill be back soon to let u know how i go
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5th May 2015, 02:05 PM #41Golden Member
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Yeah, those old rods suck. Scotchbrite's not going to do it, I don't think.
Your comments about the tungstens raise an issue to me - in a big day of welding I might resharpen 20 tungstens. I'm reasonably careful but I keep a tight arc and when I go around a corner or get out of position or whatever - dip. I could never get by with one or two tungstens. So you've either not done much tigging at all, or keeping a really long arc, or just much better than me.
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5th May 2015, 03:49 PM #42Golden Member
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In some of gazza's other threads it was pretty clear to me that this is one of the main culprits. Also in another thread (I think) gazza mentioned that he had poor eyesight. So like Karl says... fix the eyesight issue (glasses or mag lens), then the arc length thing will get under control. Then clean weld area a bit better...
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5th May 2015, 04:47 PM #43Most Valued Member
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Mick i donno about the eye vision i do need to wear glasses and i did go onto ebay looking for the lens but there are all sorts 1.0,1.5,2.0 the thing is i cant see the arc because the lens on the mask is to dark, when TIG welding i can see the molten puddle but again its too dark at times depending where im welding in the shed or outside
as for my TIG welds not looking neat at times mostly when needed i have shaky hands so i tend to lean against something or rest my elbow or wrist against something than i can TIG really nice
today i done some mucking around with the mig done a couple uphill welds they look ok and i could see the puddle because where i was working was shaded by trees but this evening with the sun over head beaming down on the back of the helmet i couldnt see much and i re-adjusted my settings and screwed up on that i thought i'd try the settings inside of the welder box but those as u know it are very poor knowledge for chinese welder
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5th May 2015, 05:03 PM #44Golden Member
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What shade? Mine goes down to 8 or 9 and I can weld right down at 30A and no doubt lower if I ever need to. I use 9 for mostly everything until I get up above about 120A. Even then the 9 can handle up to about 150A, but without much contrast.
See that first pic of mine, the 45° bent pipe with the blue pipe clamps is a jig for resting my wrist. I've got quite a few jigs like that and with my bender and cheap pipe I can make unlimited more as required. If I care at all about a weld I set up the jig clamp and no matter what position I can steady my hands. I need to make one like that but a bit longer actually, I stand inside the frame and run down the side of the jig towards the camera, towards my body, towards the inside corner, obscuring my own view. I need it longer so I can stand outside the frame and run along it in the normal way right to left or right to left. Freehanding is hard, set up some jigs!
Do some dry runs and if there's any problems, resolve them before doing the actual weld. Was it this thread or another I've read recently where someone suggested putting a towel or sheet or piece of cloth whatever over the back of your helmet so no light's coming in. I get the light like that sometimes and it sucks, makes it almost impossible to see, so you have to change things when that happens.
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5th May 2015, 05:49 PM #45Most Valued Member
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thats a good idea Legion but i dont have a pipe bender YET! lol have wanted one for a while nowbut no real use for one, i think the towl over the head would suffocate me with smoke welding and might fog up?
i done all the prep work today than ran some TIG welds whatdo u guys think of these? the first weld is me moving the torch from section to section back and forth to fill a tiny 1mm gap i cut the metal a fraction short, the second pic is the same weld just cleaned the other welds are TIG staggered across the job
this is grinding all sides of the gal steel with a flap disc 60 grit, wiping with acetone, using fresh 1.6mm tig rods,and my little welder set up on the amount of amps it has in the picture
i got full penetration because i blew a hole way to easy but was easily repaired and finished the weld
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