The Baron
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| posted on 4/4/06 at 03:38 PM |
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Tig Welding
I'm contemplating the purchase of a 'cheap 'n' Cheerful' TIG welding setup (Machine Mart inverter type set up)
I'm already very confident with my MIG set up, but want to produce some nice 'row of coins style' presentation welds similar to the
ones I produced in my apprentice days using oxy-acetylene.
I currently have a 'proper' BOC gas bottle so don’t use disposables anyway.
What do I need to look for in a plant if I want to weld steel & aluminium (not to each other.)
Cheers in advance
The Baron
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Mr G
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| posted on 4/4/06 at 03:59 PM |
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Well on the machine mart site the cheapest ac tig rig is THIS
one.
The topic pops up quite regular on here so you should be able to pick out all the info from the previous posts, however you really do pay for what you
get. You will be limited to the amps you can use on single phase kit.
Deneo recommended a few iirc but they are all ££££££  Scratch start will save you some money over hotstart but would be a pain.
Normal is getting dressed in clothes that you buy for work and driving through traffic in a
car that you are still paying for - in order to get to the job you need to pay for the clothes
and the car, and the house you leave vacant all day so you can afford to live in it.
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MikeR
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| posted on 4/4/06 at 04:00 PM |
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AC / DC tig to weld steel and ali. which means the kit you're looking at isn't good enough. You need to spend a lot more pennies.
I'll let the real experts tell you what you need now.
(sorry if this sounds a little harsh - rushing)
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Peteff
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| posted on 4/4/06 at 04:37 PM |
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the cheapest ac tig rig is THIS one.
Thats a 400v machine, you'd be better off looking at inverter based single phase machines, you can arc weld with them as well so you don't
need gas all the time.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Mr G
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| posted on 4/4/06 at 04:45 PM |
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quote:
Originally posted by Peteff
Thats a 400v machine, you'd be better off looking at inverter based single phase machines, you can arc weld with them as well so you don't
need gas all the time.
That was pointing out the cheapest
AC tig that machine mart listed - I was'nt recommending it 
Normal is getting dressed in clothes that you buy for work and driving through traffic in a
car that you are still paying for - in order to get to the job you need to pay for the clothes
and the car, and the house you leave vacant all day so you can afford to live in it.
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Peteff
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| posted on 4/4/06 at 04:54 PM |
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Something like this would do what you want but it's a big premium to pay for doing
aluminium or just wanting your welds to look prettier.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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mark chandler
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| posted on 4/4/06 at 06:05 PM |
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I,ve got the bigger brother of these on my home 240v supply (have never run it at full power though).
http://cgi.ebay.co.uk/Marshall-Dynabolt-Tig-Welder_W0QQitemZ7606378148QQcategoryZ113743QQrdZ1QQcmdZViewItem
These are fantastic welders and can be strapped for single phase. You will need to buy some really heavy wire and provide a fused spur from your
consumer unit but its well worth the hassle, a tool that will never go wrong, overheat or lose its consistance for life !
NB for Ali you need continuos HF and AC.
Regards Mark
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mark chandler
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| posted on 4/4/06 at 06:12 PM |
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I should add mine cost £650, my mate purchased a butters invertor for £1,100 which has failed twice with minimal use.
If you are serious the best tip I can give is avoid invertors (if they fail the technology is not easy to fix) but look for copper wound transformers
with HF start.
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Hugh Paterson
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| posted on 4/4/06 at 06:43 PM |
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Tig welder's
I would suggest that if u are looking at purchasing a tig welder to justify the expense of running an ac/dc machine to cope with the ali (and other
exotics), u need to be convinced that u are going to get a return on the investment. I have a high quality HF phased AC/DC 3 phase machine (Fronius),
and one of their small invertors that is now 3 years old and has done some serious quailty work in that time, (its easier to lug around) U dont have
the luxury of ali with it but the weld quailty is as good as its bigger brother, and good enough to cope with typical continuous use hobby/semi
professional work.
Shug.
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The Baron
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| posted on 4/4/06 at 07:17 PM |
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Thanks for the Replies, Have I got This Right.
Ok,
From what I can gather from the responses, the cheap ‘n’ cheerful machine mart style TIG welders are DC (direct current) machines which can weld
stainless steels and heat resisting steels, mild and low alloy steels, copper, nickel alloys, lead, silver, titanium and other metals that do not
contain aluminium, magnesium or their alloys. The ‘arc’ for these is also generated using a scratch to complete the circuit and form the weld pool.
In order to weld aluminium, the price increases as the plant must be able to generate an AC (alternating current) arc. This alternating current is
required as the surface oxidation is automatically removed by the action of the arc each time the electrode becomes positive
If a DC machine were used to weld aluminium and the electrode was connected to the positive pole it would overheat. If DC supply was used, and the
electrode was connected to the negative pole there would be no removal of the surface oxides.
Have I got his right?
Cheers and thanks for the replies. I guess that’s what forums are all about.
The Baron.
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mark chandler
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| posted on 4/4/06 at 08:26 PM |
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Sort of...
Ali forms a kind of skin, the outer surface requires more heat to melt/breakdown than the material. The AC breaks this down.
Any contamination kills the weld, even marker pen ink, you need it as clean as possible, scratch start will deposit tungstun when you start, no a good
thing.
HF sorts this out and 'cleans' the weld and maintains the arc.
Not sure why my posts are being repeated, only writing once !!!! whys this
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Hugh Paterson
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| posted on 5/4/06 at 07:38 PM |
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Oh and not all "inverter" type machines are scratch start there are a few gooduns out their now that have HF and variable output wave
although slightly dearer of course inthe region of £450-550 if u hunt around a bit. Also find recon kit quite a bit on E-bay but the normal
limitation is that its usually 3 phase!
Shug.
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iank
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| posted on 6/4/06 at 07:57 AM |
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I read somewhere that you can avoid the tungsten contamination for scratch-start.
You use a copper pad (or a 'real' copper coin) next to the weld and scratch on that. The copper gets the tungsten and the weld has a
cleaner start so should be better quality.
But I'm no expert, so it could just be an internet old wives tale. Sounds reasonable though.
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907
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| posted on 6/4/06 at 09:24 PM |
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Hi All,
I keep seeing "scratch start" mentioned on this forum.
Scratch start (full power) is usually found on Tig welders at the bottom end of the market.
High frequency start is much better as found on the better machines.
But there is another method used, "lift start".
A tiny current is fed to the tungsten, and the tungsten is touched on the work.
When the circuit is broken by lifting the tungsten this triggers the main contactor and gas solenoid.
It is used in sensitive areas, (oo err missis) oil refineries, hospitals, etc, where hf could track back
or interfere with radio signals, heart monitors and the like.
I've seen inverters with this on, I believe some hf jobbies are switchable to it.
No good for ac (ally) I know, but worth thinking about.
ATB
Paul G
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David Jenkins
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| posted on 7/4/06 at 07:42 AM |
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My TIG has a low-current scratch start, which sounds like a cheapo variant of what Paul just described.
touch down the tungsten, lift, then the electronic gubbins turns on full power. It doesn't have all the other useful stuff though... 
David
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Peteff
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| posted on 7/4/06 at 09:29 AM |
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I've seen lift arc tig advertised as well as scratch and HF start, now I know what it is. I've seen something called an arc bug for
striking up a stick welder on. It's magnetic and sticks to your work where you want to weld. It might work with tig. Frost have it
here
[Edited on 7/4/06 by Peteff]
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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locostv8
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| posted on 10/4/06 at 04:31 AM |
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A thought for a low cost TIG
http://classicbroncos.com/homemade-welder.shtml
http://wrangler.rutgers.edu/gallery2/v/7slotgrille/hssss/
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