Welding

Like others in this group Iím fed up with paying BOCís excessive rental charges, which makes the information that Iíve recently
discovered very good news.
I donít know if it is generally known but Adams Gas http://www.adamsgas.co.uk/index.php?option=com_virtuemart&Itemid=54 now supply Oxygen as well as their Argon mix gases to the hobby market. They also now have local agents so delivery charges can be avoided.
Iíve used Adamsí Argon mix for a couple of years and although it isnít quite as good as Argonshield it is good enough for me. So when the rental runs out on my Oxygen, BOC can have their bottle back and Iíll get my Oxygen from Adams.
Which brings me to a question, welding with Oxy/Propane Ė does it work?
Iíve read on a welding forum that you canít weld with Oxy/Propane, which would be a pity as it would stop me completely escaping from BOCís clutches.
Another question, Iím considering replacing my MIG with a TIG as I would like to be able to weld aluminium and not just melt it which I tend to do with gas! This is only being considered because Chinese made TIGís like this http://www.frost.co.uk/eastwood-tig-200-ac-dc-welder.html?gclid=CJqa7a6y7qwCFSFItAod_2CLHQ are getting to be almost affordable.
Has anyone experience of this type of TIG and are they any good?
Thanks in advance.
John H
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John H wrote:

You mention MIG, TIG and gas welding in the same sentence as aluminium, are you having problems with gas welding aluminium? Also what are you intending to weld. Gas welding aluminium is quite good for thin sheet and leaves the metal in a soft state for further working but is not great for thicker sections due to the heat involved. Personally I never had an issue with gas welding aluminium as I noted a subtle change in the surface appearance before it drops on the floor and therefore can control the rod and torch to produce a good weld although not as pretty as in some demo videos I've seen. Can't comment on cheap TIGs as although I have one it wasn't cheap. I started with a Pickhill welder and MaxArc HF unit and AC/DC unit and they worked but aren't modern solid state stuff.
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I don't do enough gas welding of aluminium to be proficient. It's over forty years since I did a C & G practical course and I have never done welding other than for my personal use. What I want to make are catch and oil tanks and similar constructions using approx 3mm sheet.
If it is possible what I want to achieve, is to use Oxy/Propane gas for welding/brazing and heating, and TIG for aluminium and heavier steel constructions.
Is this likely to be possible?
John H
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On Sun, 29 Jan 2012 10:10:56 -0800 (PST), John H

Oxy/propane will not work for welding steel because the flame is not hot enough and will not put enough heat in a concentrated spot. Acetylene burns much hotter than propane. Propane will work fine for brazing. The inexpensive TIG machines sold in the USA are all DC output machines. While you can weld aluminum with DC it is harder to do and helium is needed for the shielding gas. The aluminum must be very clean for DC to work well. Sometimes this means cleaning the aluminum with a weak HF acid cleaner after cleaning by conventional means. All the cheap tig welders I have seen here in the USA are also lift-arc type designs. Which means you must touch the tungsten to metal to get them to start the arc. More expensive TIG welders use high frequency at high voltage to establish the arc. I have spoken with folks in the USA who have used a Chinese made inverter AC/DC tig machine that costs about $650.00 US. A couple brand names are Luxor and Riland. If I was in your position and insisted on new then I'd try to see if you can find anyone on your side of the water that sells these and try it out yourself. Or maybe get a welder to try it and evaluate it for you. A used machine might be your best bet. One of my welders is a Miller Gold Star that was made in 1974. It still works great. It is an AC/DC machine with an amperage range from 1 to 300 amps. But it is huge and heavy compared to modern inverter machines. This makes them cheap over here. Another welder I have is a Lincoln SP125 PLUS mig welder. I bought it used for $250.00 and it came with a gas bottle and flow meter. This used machine performs much better than a couple new Chinese machines I tried that were priced at about $300.00 new. Since I bought the machine I've run more that 120 lbs of wire through it. Another reason to buy used, known high quality, over new, unknown quality. Eric
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I have one of the £500 Chinese 200amp AC/DC TiG sets, I also have a BOC Transtig 200 amp AC/DC set. The Chinese set works far better than the BOC set, in fact that has now been relegated to backup mode.
Biggest advantage is it's cut the electric bill down by about £70 a quarter. I think the BOC set got more heat off the gimbal of the electric meter than off the torch !!
John S.
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