Arc welders
I thought this would be useful as no doubt you'll have seen a very cheap Arc welder in somewhere like Aldi or Netto for something like £40 and you'll be thinking "Hmm..... wonder if I could do that?"
If you've never done Arc welding before and have only done MIG, your first attempt will be absolute shite! The best way of learning Arc welding it to watch someone experienced with Arc welding and get them to really show you how it's done. I speak from experience here as I was used to MIG and spent about an hour trying to arc weld and simply couldn't. The Haynes welding manual is no use whatsoever as it's very difficult to describe. It's all to do with constantly moving the rod closer to the weld whilst moving the whole weld forward which is a pain in the arse to learn but once you've got it, you'll be amazed at how neat and strong the welds are!
Here's an example of 6mm steel T-joined with Arc welding:
In my opinion, I think this looks much nicer than the MIG weld above. Arc welding is very different to MIG in that good appearance is almost always a good indication to the quality of the weld. Another thing is you will have to chip off the "slag" to reveal the weld. The slag protects the metal as it cools but it's very satisfying to chip it off to reveal shiney beautiful welds. Plus it also means you can shout "Shut it, you slaaaag!" to your heart's content.
Trouble is, Arc welding isn't really suitable for most car repairs due to the amount of heat generated and that welds like the above are more suited to thicker metals.
So why have I told you all this and why should you bother with that cheap Aldi Arc welder?
Simple.... SPOT WELDING!!!
Normally when spot welding two pieces of metal together using MIG, you have to do a "plug weld" and drill a hole through the top layer of metal in order to weld the two together.
With an Arc welder, all you need is a 2.5mm rod stamped "6013", set the welder to about 60 amps and ZZZAAAP! 1 second later you have a perfect spot weld!
EDIT - use 30-45 amps on a budget machine - this was a very expensive "inverter" type machine using DC but I've since discovered budget machines are all AC and require less power.
Here's a spot weld on two 0.7mm pieces of steel (the thinnest I could find):
The black scorch mark line is where I started the Arc - with practice you won't need to do this. Notice this works on rusty metal too!
And the underside:
And this is me trying to pull the weld apart - I couldn't!
I'd recommend practicing a few times on some scrap steel to get the hang of this. Also, you've got the advantage over spot welders as you can reach areas that normal spot welder "clamps" won't be able to reach.
If you can find a spot welder this cheap, I'll shave my beard off and eat it!
EDIT - it's worth changing the cheapo clamp arc welding torch that comes with budget machines with a higher quality "twist type" torch - these are only about £6: