Thank you - I'm just on eBay and near to me North Manchester, there are loads of arc welder being sold. Most look like cheaper models but do I buy anything in particular - current rating, price. Etc?
Depend on your budget and how much space you have.
* Forget the cheapest new AC (transfomermer only) units. You are limited to one type of stick (rutile) . Also current range sucks even more than duty cycle. Using them is a pain if you are starting welding. Old hand can use them ok.
* If you have space and good 3-phase feed, industrial old heavy DC unit is a way to go. Some have power unit and some additional "box" for remote control, parameters or wire feed / TIG unit etc. They are big, heavy, last forever and if they break, many people can fix them. You wait a little while and you are bound to find one.
* If you don't have 3-phase or want to cram it into a small space, new inverter is pretty much way to go. Here you pay on duty cycle and quality cables. If you stay away from the cheapest sub 100A units you are fine. They are build for price, therefore no filling them with sand/dust/bumpping/dropping. Electronics is not very friendly for maintenance.
Pekka
* Update#1
Addition of few examples I know (there are bunch of fairly simililar ESAB/bunch of italians)
Telwin TECNICA 151/S - 230 V. About the size and weight of serial box, about 200-300€ range. Does what it says. Low duty cycle, but on that price and when doing hobby work it's a compromise you can live with. Two of my friends have older version of this same machine and they love it. They stuff all welding equipment (excluding sticks) on one plastic storage box leave it on garage and then bring the box next to work they need it. Short cables, but standard bayonet. Place on elevated surface near you (short cables and this unit does not like rain/water/dust. You may consider buying just the unit (sometimes cheaper) and longer/better cables. If nothing else lget Least longer grounding gable it probably saves you from dropping/dragging this baby.
Like that:
http://www.ebay.co.uk/itm/WELDER-TECNICA-151-S-230V-ACX-PLASTIC-C-CASE-code-816202-TELWIN-/260941784502?pt=Utensili_elettrici&hash=item3cc157a5b6There are some versions of this that have "Lift TIG" capability and even if you don't need it now, you may want to buy a model if it is only 50€/£ more expensive. They show up sometimes on welding shops a little used. Someone tried TIG, got hooked and wanted to shell dough for a proper HF-unit. But IMHO it is not "the thing" on the list. Unless you really want to try some TIG later on. It's a compromise, but if it does not cost much extra it's worth of considering.
Telwin manuals are pretty crappy. Also their affinity to small controls and short thin cables tells where they save money.
Like this:
http://www.telwin.com/webtelwin/site.nsf/webapridocumento?openform&E|3||816014|81
Pretty decent for the price. These specs are real, not pony HP. One thing we like these is that they are generator friendly = you can use some extension cables, some cheaper units don't respond well on 10 -20 m mains extension cables.
There are some cheaper ones in "supermarkets", but they are always limited on one feature or another. Often with integral 1 metre long useless cables or something. 10% duty cycle on advertized current (eg. 90A or something lowish like that). Some people have bought them, but normally they work just enough that you can't really return them into shop, but they are no joy to use. Pretty much in par with cheapest AC/transformer units, except you can use DC-sticks (Yeaaaa...) and startting is easier.
Then there is a step up when you dig deeper.....here around 500-600€. That money buys a very decent machine that you really can't blame, maintenance works if you need one and you see them used by professionals on maintenance work. Have you anybody ever heard bitching up on Fronius (unless dropped on toes)?
So, eBay may give best last price, but most fitting machine is usually found visitting/calling few welding supply shops. Least here. Try to bundle up longer cables (even much used grounding cable/clamp is great), grounding clamp, good electrode holder, gauntlets or such). My friend got really crappy looking grounding cable/clamp, but it was good 5m long and thick industrial just to seal the deal.
* Update#2
Forgot to say that long rambling above is not Telwin endorsement, but personal view of me and some experience I and some friends have.
I was going to add some more opinions on different brands, but noticed that GYS has changed models too much for any usefull input and ESAB/Kemppi is probably too local here to have any real value to Chris.
o-o