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Attempting to weld
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Knightrous
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if the rod welds itself to the steele, you either twist the rod quickly to u stick it or you turn the welder off and break them apart. Otherwise the whole welding rod will start glowing and you might not want to see what happens after it.
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Post Wed Sep 08, 2004 7:59 pm 
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timmeh
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What happens if its sticks and you cant yank it off can you blow up something?
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Post Wed Sep 08, 2004 8:03 pm 
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marto
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Its easiest to try and twist the rod off. The rod will just be wrecked if it gets stuck for too long.
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Post Wed Sep 08, 2004 8:06 pm 
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timmeh
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So i cant blow up the welder or fry myself it will juts wreck the rod
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Post Wed Sep 08, 2004 8:08 pm 
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Totaly_Recycled
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You can give the holder a twist and just pull the holder off the rod its its realy stuck and then pull the rod off the job when it cools a bit .. if you have the amps set right you will hardly ever get it stuck

Post Wed Sep 08, 2004 9:40 pm 
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timmeh
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As long as nothing major happens if it gets stuck ill be fine
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Post Wed Sep 08, 2004 9:43 pm 
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timmeh
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Im buying my own ark welder in the next week after i buy my battery cells off brett.

Its going to be fun turning bits of steel into plasma! Very Happy Very Happy Very Happy Very Happy Very Happy

Are welding goggles as good as a mask cos they are a little more compact and easyer to use?
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Post Thu Sep 09, 2004 8:14 pm 
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Timothy Forde
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ok just wondering can you weld ali with a oxy?
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Post Thu Sep 09, 2004 8:32 pm 
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mytqik



Joined: 26 Jun 2004
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quote:
Originally posted by Team Hell Bent!:


Are welding goggles as good as a mask cos they are a little more compact and easyer to use?


Well the goggles you refer to are for oxy/fuel welding. They are generally around a shade 5-6 lense & are solely for the oxy/fuel process.

The mask is the *only* option. Apart from having a lense that is around 11-13, they also stop all the nasty UV rays damaging your face, causing skin burn & possibly skin cancer.

If you can afford it I would highly recomend the purchase of a self darkening helment. These units normally have a larger window to see through making the welding process for beginners easier. Once turned on they are about a shade 3, which allows you to see fairly well, but also allows you to use other power tools (grinders etc) without having to take the welding helment off & put on your safety glasses.

Once an arc is struck by the welder the lense automatically darkens in a millisecond & you have a shade suitable for arc/mig welding. The cheap units are only fixed shade & battery powered, then the more you spend the more options you get eg: solar powered & lense shade adjustment.

quote:
Originally posted by Timothy Forde:


ok just wondering can you weld ali with a oxy?


In a word: no. Aluminium exibits a strange behavour in that its oxide coating which naturally forms with contact with oxygen actually has a higher melting point than its parent metal. The melting point of Al is about 550C but the ALO2 oxide melts at 1300C. Eg if you heat a piece of aluminium until is it cherry red, you will notice that the outside does not melt, however the metal has lost all strength. It actuallys melts from inside out.

Therefore to weld Al you need to remove this oxide layer. This is done by reversing the polarity of the welding process, so the arc actually goes from the workpiece to the handpiece. As the ALO2 is not conductive but the AL is the arc must pass through the ALO2 coating. This "shatters" the oxide coating & allows the AL to be welded. This process is best performed by an AC TIG, or a MIG & maybe an ARC welder if you have the right rods. However it is the least successful method.

The reversing of the polarity also help in that al of the heat is now generated in the hand piece. As AL has such a low melting point, the less heat induced into it the better the weld. People welding thicker sections of AL with a TIG will actually use a water cooled torch.

As the oxy/fuel welding relies on heat. not electrical current it can not weld AL. The only option would be to braze the AL together if you only have oxy/fuel equipment.

Hope this helps.

Post Thu Sep 09, 2004 9:21 pm 
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prong
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hmmm in regards to self darkening welding mask Dumhed bought one a little while ago for $100 from Mitre 10. It is the normal LCD type, with battery and solar power and you can adjust the brightness. Seems pretty good, it entertained me for a few seconds looking at bright things to make it switch to the darker mode hehe Smile

Post Thu Sep 09, 2004 11:55 pm 
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Nick
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@ Mytqik: Sounds like you are an expert on more than just design!

I have a fairly good 200amp MIG welder withthe polarity set right for Aluminium (according to the manual) I think I will reverse things just to see what happens...

I had a specific problem that I have not seen in any manuals: when welding right-angle butt joints on Basilisk, some joints had good penetration at the edges (too good in some places, with undercutting) but at the centre, there is NO penetration and the metal surface has a carbon deposit and pitting. I am using the correct leading torch position (possibly not the best angle) and I always see quite a bit of carbon deposit ahead of the weld bead. Ever seen that problem before?
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Post Fri Sep 10, 2004 11:39 am 
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mytqik



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Nick,

You mentioned the build up of carbon?? I am therefore assuming you are talking about welding steel, as there is no carbon at all in the aluminium welding process. Pitting is usuaaly casused by two things:

1. There are contaiminats in the weld pool. This is usually caused by by not cleaning the surface of the workpiece before welding. A rub with a good quality stainless steel wire brush should fix this

2. Not enough gas flow. The gas is present to sheild the molten weld pool from the atmosphere. If not enough inert gas is present during the welding process, atmospheric air ie oxygen can come in contact with the molten weld. When hot/molten steel comes in contact with oxygen, it oxidises rapidly. This is the same property that allows steel to be oxy/fuel cut, but aluminium can't.

Nick, hope this helps. If you can take some photos of the welds you are refering too, I may be able to offer a more detailed answer. Also can you provide some more detials, ie material thickness, electrode thickness, amp settings, gas flow setting & gas type, is the electrode on the positive or negative etc. Cheers.

Post Fri Sep 10, 2004 1:51 pm 
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Nick
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Sorry, I should have been more specific. Its all 5mm aluminium that I am welding. I have the Argon turned up about 10cfm from memory. When I had it higher it made little difference except that it cooled the weld quicker & I needed more current.

A "good" weld (it's all relative Wink ) has a nice even bead with very little oxidation and carbon soot for around 5mm either side. further away, everything has grey/white smoke film on it. a not so good weld is lumpier & has ocassional voids down to the base metal in bad cases. The problem I mentioned before happens somewhere in between good & visibly bad.

I clean the ali with either a stainless steel brush or fresh sandpaper just before welding. Its all 5083 alloy plate and I checked the wire is a compatible grade.

The carbon I mentioned is a soot deposit that wipes off easily. Its always deposited ahead of the weld direction. I am using a fairly high current and feed rate to get a short arc.

Keep in mind that I learnt all this out of books or web pages - I could be doing everything wrong & not know it Confused
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Post Fri Sep 10, 2004 2:11 pm 
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Eyce



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I tried welding at school for Metalwork, I had a nervous hand, but surpisingly, it's quite easy to do, but mastering, as many people have said, takes time.
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Post Fri Sep 10, 2004 6:51 pm 
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Nexus
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Was wondering if I should look around for a cheap second hand welder so wanted to ask if theres parts on these things that need replacing,

Is a second hand welder just as good as a new one or does it come with its own problems?
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Post Fri Sep 10, 2004 6:59 pm 
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