Re: OT: TIG Welder
Sorry to be a late commer to this discussion, but i've been on holiday!!
- i have to agree with everything Nick has said.
I'm an amature who spent one years bonus on an AC tig set, i convinced
myself i MUST have one! - lol
I had been welding for 20 years (MIG - Gas), building cars etc and after
6 months of trying to stick alley together, ended up going to colledge
for a year to learn how to do it!, i wanted to send the set back!
A foot peddle is a must, i bought mine after the set and it just makes
life sooooooooooo much easier.
Mother - I'm in Sheffield (Handsworth) if you want to come and talk to
me and try out my set, drop me a line. I got mine ex demo from Lincoln
Welding supplies (attercliffe), and it came in about 2.2K for the lot,
but they did me a good deal.
I have just welded a cosworth cylinder head on a 150 Amp torch and i
didn't need the 250A max that my machine goes to either. all this and
off a normal 3 pin plug!
hope this helps?
Nick Williams wrote:
> On Fri, 2 Sep 2005 20:19:01 +0100, Badger wrote
> (in article <email@example.com>):
>>"Rich" <firstname.lastname@example.org> wrote in message
>>>So you need more current to weld ally ( or make blobs on the floor ) is it
>>>very hard and what is the foot pedal I have seen on some big welders?
>>You need more current initially to "pool" the metal, due to ally dissipating
>>the heat through itself quicker than steel, that's why it's so easy to make
>>ally puddles on the floor! oops! The foot pedal is an alternative to the
>>button on the hand torch, on welders that have this, some cheaper machines
>>are what is referred to as "scratch-start", where you have to make contact
>>with the tungsten electrode to fire up the arc.
> The foot pedal is (usually) a current control so you can wind the current up
> and down as you progress along the weld. IME this is pretty much essential
> for welding ali since you need to put a lot of heat in to get the weld going,
> and then back off one the material is hot or you'll make a hole. You also
> need to be able to back the current off as you finish the weld or you'll end
> up with a pit in the bead. Some machines will do this automatically, ramping
> the current up when you push the button on the torch and down when you let
> go, but the foot control gives you more flexibility.
> There's loads of good welding advice on the net. Hang out on
> sci.engr,joining.welding for a while and some good advice will come along
> soon. Miller Electric and Lincoln Electric both have lots of stuff on their
> websites, too, and there is also The Welding Institute.
> Unless you are doing very long runs (feet of bead at a time) at currents over
> about 150A you won't need a water cooled torch. I have a 200A TIG machine
> (Lincoln) which will easily weld 4mm Ali plate and will run off a 13A socket
> (although probably not forever at full output). It was quite a lot of money,
> though (~2k).
> Apart from the oxidisation issue with Ali (which is why you need AC) the big
> problem is its heat conductivity. If you start with cold pieces of material,
> they just soak the heat away from the weld so it's difficult to make the bead
> flow properly. Once the surrounding material is hot enough for the
> temperatures to stabilise then laying a pretty bead isn't much more difficult
> than for steel, but if I'm only welding a short piece of material, I find
> I've usually reached the end of the weld before this happens.
> You can use the same shielding gas (pure argon) for TIG welding ali or
> steels, but you will need zirconiated (red) electrodes for steels and
> thoriated (white) electrodes for Ali. You're supposed to be able to use
> ceriated (grey) electrodes for both, but I've not had a lot of success with
> I've never played with scratch start (aka 'lift-TIG') but I understand that
> for welding Ali, life is a lot easier with HF start. With Ali, you really
> want to avoid the contamination of the bead which comes from metal-to-metal
> contact between the material and the electrode. AIUI, lift-TIG is the poor
> man's option and anyone who has HF start will not use the lift-TIG option
> even if they have it available.
> The most important thing with TIG welding is to prepare everything carefully
> in advance and be scrupulously clean, especially when working with ali. The
> books all say this, and it's easy to ignore, but it is absolutely true and it
> really makes a difference. I started out with a stick welder, progressed to
> MIG and then on to TIG, and as I have moved from one process to the next, I
> have learned (the hard way, of course) that each is less forgiving of
> dirt/corrosion and poor fit parts than the last.
> I'd also recommend Lincoln equipment . It's more expensive than the
> Clarke/SIP equivalents, but it's professional gear, and I find the guy who
> runs their Sheffield retail outfit very helpful and easy to deal with.
> 1990 90 2.5TD