PerspexIt
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 posted on 14/3/03 at 09:41 AM |
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Welders: MIG, TIG, inverter..
Hi All,
yesterday i received the book "Welder's Handbook: A Complete Guide to MIG, TIG, ARC and Oxyacetylene Welding", suggested on some of your web
sites.
They wrote the MIG it's easy to start with... but there are also some drawbacks. I took a look also to the TIG chapter, and seems (at least for what
i can understand) better.
My experience on welding is limited to some garden-level works using an arc welder.
Since more or less the prices of a MIG and a TIG is the same, somebody can give me a suggestion?
I'm going to weld round tubes, so the "precision" they talk about in the book can be a +1 to for the TIG option.
-P
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David Jenkins
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| posted on 14/3/03 at 10:07 AM |
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A good TIG is far more expensive than a MIG! The "same price" TIGs are usually "scratch start", which means that they don't have the
high-frequency, high-voltage starting arc that makes life so easy. You literally have to scratch the tungsten across the work to get the arc going,
and this can cause a bad weld - I have one of the "slightly more expensive" TIG sets, and this keeps the arc current low until the tungsten is
lifted, which helps.
Also, the cheap sets don't have the all-important control electronics such as "ramp up" and "ramp down", and often don't have a foot control for
adjusting current. Also, most of them are DC only, which means that you can't do aluminium.
TIG will give you a better weld, but it's a lot harder to develop the technique - have you ever tried the old party trick of tapping your head while
rubbing your stomach round and round? Multiply that by 2 and you're about there! You have to maintain the arc distance, move at the correct speed
along the weld, dip in the filler rod, and use the foot pedal to give the correct current according to where you are on the work and the state of your
weld pool.
However, if you have previous experience of oxy-acetylene welding then consider TIG - the skills are similar enough to make the transition easy.
A decent DC scratch-start TIG like mine will cost around £350 - £400. For that much money you can get a damn good MIG, regulator and your first
cylinder!
Spend your money on a good MIG, and learn how to use it.
regards,
David
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James
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| posted on 14/3/03 at 10:20 AM |
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Hi P,
I've done quite a lot of my chassis with TIG (at college) but I've also got a SIP150 MIG at home that I've used quite a bit now.
Here are my opinions only backed up with a little ignorance: 
Cost:
They don't cost the same! You can get a MIG that'll do what you need for this project for (even at Halfords prices!) under £300.
Also, you only need a flap down/hand held mask.
For £300 you might be able to get one of the 'little' TIG boxes but doing it that way you lose some of the few advantages you have with TIG which is
the control- ie. a footpedal (to vary current) and the HF (high frequency) start.
To get the full benefits of TIG you need a decent setup and that is a couple of thousand at least.
Without a HF you've got to worry about striking the arc (which leaves bits of filament in the weld).
When it comes to the mask you pretty much have to have an LCD one as you need both hands to hold the torch and the filler wire- these are around
£100.
Control/Penetration:
MIG: you set it up to the best of your experience and point and shoot.
If you get it wrong, grind out the weld and re-do.
TIG: Excellent penetration/fusion- it can all be varied by the foot pedal as you work. If you mess the weld up you can just go back over it with the
torch without adding any filler wire.
Speed:
MIG: Setup current/speed then point and shoot all day- easy and fast.
TIG: First you need to grind the tungsten filament to the correct profile (depending on what you are welding) for which you need a special grinding
wheel. Then, as you work, if you get any metal onto the filament (and bear in mind you're holding it 2-5mm from the weld pool all the time) you've
got to dismantle the torch, remove the filament and then grind it down again. This can all take a very looooong time!
To conclude:
TIG *is* brilliant- looks lovely when done well and gives (with the right setup) excellent penetration and control. Unfortunately it's just so
slow.
MIG is fast, easy and with practice will look good and give decent penetration.
Basically, in my opinion for a Locost MIG is the way to go- if you don't believe me book onto a welding course where you can do both types and make
your own mind up- but I garantee after awhile you're gonna get mighty bored of grinding tungsten rods! 
Good Luck, hope that helps,
James
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James
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| posted on 14/3/03 at 10:23 AM |
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Well, I spent so long gibbering on that David managed to say pretty much the same thing before I finished my reply- oh well, atleast he agreed with
me!
James
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PerspexIt
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| posted on 14/3/03 at 10:54 AM |
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Ok, ok... ok
You convinced me. Just talked with another guy here, and he said the same.. so back to original MIG idea.
Thanks!
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PerspexIt
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| posted on 14/3/03 at 10:57 AM |
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James,
there is a particular reason for make it +10? I was thinking about the same but "just" +4.
Wich tubes are longer? Cockipt?
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racer
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| posted on 14/3/03 at 04:32 PM |
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Hi,
I started with a MIG but when I used an touch - start TIG inverter, I decided to use it for the following reasons :
1. The tube that is used for the chassis is thin and with the inverter you can do a very accurate job.
2. TIG is the most "cold" of the welding processes.
3. You can see exaclty what you are doing.
The are 3 more things you have to consider :
You MUST have a welding helmet with a light sensor (because you will need both hands to work)
Welding process is a little bit slower.
Because of the touch - start, you will have to sharpen the tungsten stick from time to time.
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Mark Allanson
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| posted on 14/3/03 at 07:43 PM |
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I learnt to TIG weld before they invented these reactolite lenses, they are not essential, just useful in certain environments. With a normal
lightweight helmet (essential), you have the mask above your head, set up your weld and 'nod' the mask down into position - job done.
When working in a medium sized engineering firm, some hot shot graduate junior manager bought 10 of the reactolites, they were crazy money then, about
£250, when I was earning £130 on skilled man wages. There were eight of us in the welding shop and all wearing these bloody big 'darthvader' things
on out head. as soon a one bloke flashed up, all the rest went blind cos all the masks reacted to the flare -BLOODY ANNOYING!!!
End up we got Rupert (spotty faced graduate) to demonstrate. While he was setting up, the oldest of us (and nastiest) extingushed his sexy ahotaline
torch and filled a condom with the escaping mixed gas. He tied a knot in the end and put the oversized phalus in Ruperts welding bay. Rupert not being
to good a welder (he had read about it alot) dropped a fair few sparks.... .... he literally shat himself, the new star wars gadgets lasted 2
weeks longer than he did!
You don't need to spend that mones on a new mask, but do get EW9 lenses with evtek protector glases on both sides, the gold plated filters are the
best you can get for both MIG and TIG. Screwfix do a love;y set of kidskin TIG gloves for £3.99, which are good to use for MIGing delicate stuff, such
as brackets etc
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James
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| posted on 17/3/03 at 10:10 AM |
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PerspexIt wrote:
quote:
James,
there is a particular reason for make it +10? I was thinking about the same but "just" +4.
Wich tubes are longer? Cockipt?
Err, well I had a 'good' idea about how to make the chassis wider more easily- it turned out it wasn't!!!
I wouldn't recommend anyone follow the same route whatsoever!
It's not particularly in the cockpit- mine's bigger in all dimensions! 
Regards,
James
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