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12th Sep 2011, 08:20 PM #1Novice
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problem TIG butt welding thin material
I have a DC Kemppi miniarc 150. I usually don't tack anything thin, but I have a truck that has some panels that needs some TLC. Obviously the stick won't do .8mm panels
So I wander off to the local Welding shop and Ralph there shows me the TIG attachment for my machine, and a little consumable gas bottle. $201 and I'm ready to go.
Before that I ask if I can try it in his workshop area. I have some .8mm with me. He hooks up to the big gas bottle, puts in a 1.6mm tungsten rod, and off we go! We both had a go. After 30 minutes neither of us could get much of a tack. Tried and tried. I asked if going down to a 1mm tungsten rod might help. He thought it wouldn't because you couldn't get enough amps with that. Not sure what he meant there.
Anyone use a similar unit to TIG weld thin panels?
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12th Sep 2011, 10:44 PM #2Member
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what problem were you having getting a tack, just burning the plates away from each other instead of getting a puddle across both plates?
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12th Sep 2011, 10:53 PM #3
The way read it the tungsten at 1mm is too big.
For .8mm th ( 1 amp per thou) 1/2 that .5mm thoriated electrode ( for stability) and set to run at around 30 to 35 amps.
Question though, is about the Kemppi. Will it be stable running that low.?
Grahame
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12th Sep 2011, 11:54 PM #4Novice
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13th Sep 2011, 12:18 AM #5Novice
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13th Sep 2011, 12:57 PM #6Most Valued Member
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As you no doubt realise at this point, you have picked quite a hard task.
Cleanliness of your parent metal will be most important as any paint residue or rust etc will hamper your success. I believe that you could achieve the weld with a 1.6 tungsten, but a 1mm would probably be ideal. Make sure that your tungsten has a fine point as this will concentrate your arc more effectively, (2-3x electrode diameter is the normal taper and I would lean towards the 3x), make sure that your grind marks run parallel to the axis of your electrode. You will need to hold a very short and consistent arc length so you will need to ensure that you are in a comfortable position and that your stickout is adjusted so as to allow you to rest the cup on the work to steady yourself. As to filler wire, I would use some 0.9mm mig wire as it will melt off a lot easier than 1.6 filler rod.
Joint fitup will need to be perfect and if possible a chill block behind the joint, (copper or aluminium as a second choice), if utilised will make your job easier.
As you are doing body work by the sound of it why not invest in a punch and flanging tool? This is a tool that forms a depressed flange along the edge of a panel allowing you to lap the rust repair section on top of the flange, finishing flush on the surface, the punch part of the tool does just that, punching a hole approximately 5mm dia. that you then plug weld. If you do not wish to do this then you don't punch the holes.
A lap joint will be far easier to weld and finish than a butt joint, this is the way professional panelbeaters repair such panels as it is much faster and less prone to misalignment and distortion compared to a simple butt joint.
This link shows one.
Cheap Flange/Punch Tool from $119.90Last edited by Karl Robbers; 13th Sep 2011 at 01:06 PM. Reason: Add information
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13th Sep 2011, 06:16 PM #7post no bills
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Did you change the polarity? To electrode negative?
www.methodmetal.com.au
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13th Sep 2011, 07:03 PM #8danielson
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just went out to the shedand butted up two .8mm (stainless) scraps and welded them together,amps 35 1.6mm rod.did you reverse polarity and switch over to tig settings?
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13th Sep 2011, 11:45 PM #9Novice
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13th Sep 2011, 11:47 PM #10Novice
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14th Sep 2011, 12:47 AM #11danielson
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14th Sep 2011, 01:25 AM #12Novice
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He had it on around 20 amps. We were both mainly burning the edges away trying to get a puddle. I got too careful and started getting stuck too often. I was just trying to tack, no filler rod.
Have you ever tried .8 mm with a 1mm electrode? I rang the guy up again to day and said I would come over and give it another crack when he gets 1mm. He said hw ould be getting them in this week. I felt a bit embarrassed spending all that time over a 200 dollar rig. But he seemed keen to figure it out himself. Also, it is the Kemppi TIG gun, not an el cheapo and he told me it was a 1.6mm thoriated tungsten electrode.
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14th Sep 2011, 11:35 AM #13post no bills
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There's no reason why you can't do it with 1.6 electrode.
First things I'd check is if the gas is the right one, straight argon? Flowing out of the torch correctly? Tungsten is still clean after the weld is finished? The steel is clean? Not greasy or got any sort of coating on it?
Out of curiosity, have you tried it on some thicker material?www.methodmetal.com.au
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14th Sep 2011, 04:41 PM #14Novice
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I'm pretty sure it was straight argon. I will check.
My intention is to buy a disposable bottle, so I hope that will be ok. It did have that light grey sheet metal coating. We sanded that off a bit.
I did not try thicker. I have DC stick welded (tacked) 1.5mm steel with a 1.6mm stick - after some mucking about and learning and getting some touch. So in buying the TIG I only had one thing in mind and that was to weld thinner stuff.
Question: given proper prep should it be fairly simple to tack using a scratch TIG 0.8mm sheet metal?
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14th Sep 2011, 07:23 PM #15post no bills
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Sure it's doable but some skill is needed to do it consistently. The problem with the scratch tig is it's hard to get the arc in exactly the position you need after the arc has been struck. And even harder if you have a manual flip down helmet.
A lot easier and cleaner with HF start.
If the join has a very nice tight fit up, you might have better success actually using higher heat. I know it sounds crazy, but you can get a quick hot tack to instantly fuse the edges on higher heat without having to wait around for more heat to sink into the surrounding metal when using lower amps.
Try putting a back up bar behind the weld like some nice thick aluminium or copper (as already mentioned) and even better if you keep it in the fridge/freezer.www.methodmetal.com.au
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