RussianRouter":2awuinle said:
Broke the bank and went for this one....
http://www.screwfix.com/prods/30030/Pow ... elder-150A
Hopefully it'l lcome monday free delivery as well.
I can't speak to that specific welder but some thoughts from a rank amateur:
(1) Argoshield (argon-CO2 mix) type gases work by far the best on normal mild steel. Pure CO2 spits and leaves rougher welds. Pure argon for stainless. I've not tried gasless, but I'm told it leaves flux residues and needs more cleanup afterwards. You can 'help' welds a bit in thick material by pre-heating with propane or MAPP gas (I've done this with mixed results on cast iron - not officially MIG-weldable!).
(2) Practice a lot. Mark the settings you use on the gas regulator, the current and the wire feed, so when you find a sweet spot, you can keep it.
(3) if you don't have a small angle grinder it's really helpful. Grind through your first practice welds and see if they're good.
(4) There's a Haynes manual on welding: it's pretty good and not expensive. THe on-line tutorials may be better, as you can see better what's happening.
(5) I struggled with a conventional welding shield/helmet for years. The biggest problem is you can't see anything just before you strike the arc, and if I had a pound for every cockup arising... Occasionally, you get out of sync when setting something up and strike an arc with the helmet
up: trust me, arc-eye is not at all fun! I got an auto-darkening one for about 65 quid a couple of years ago and never looked back 8).
(6) You may tan well (I don't), but trust me (again!), welding 'sunburn' is truly nasty: wear a cotton boiler suit (not synthetic!), with cuffs and a high collar. Make sure other people (especially kids) can't accidentally happen on you welding and 'catch a flash' of the arc. It can be damaging to the eye over quite a distance.
(7) Strong magnets are excellent for holding plates together for tack welding. Mole grips are also brilliant,
( 8 ) I've wrecked the top of my w/w bench with spatter (the anti spatter sprays work!). Hardboard, I found out too late, is a good cover (shiny side up). Beware hot stuff and wood finishes - arcs cause vapours to explode!
(9) you can do thick material by cutting V-shaped edges for a butt-join and filling with weld. You also need to clean surfaces well - any rust causes lots of spatter and useless welds, and galvanizing causes very nasty toxic fumes (you can grind it off beforehand though).
(10) For good quality welds in thicker material you need a good mains supply. I recently fitted a 16A plug to mine (which is an old SIP, nominally 120A ), wired straight back to the garage consumer unit, which itself has abnormally heavy cable supplying it: the weld quality improved markedly. There is a high surge current when the arc is struck, which tails off a bit whilst you're drawing a bead, and that initial demand is what you have to allow for. If you must use 13A plugs (sometimes it can't be avoided), don't use extension leads - each plug+socket includes at least one fuse, which is essentially a resistor.
(11) yours may have it already, but if not, a PTFE torch liner really does work well. Again, mine improved markedly when I changed it. Keep a sharp medium file handy, as I often 'weld' the wire to the copper torch tip, and filing off the end usually frees it up (it's worth having a handful of copper tips handy too, as you'll get through quite a few).
Sorry - way too much rambling. I hope some of it is helpful.
E.
PS: I'm told the metallurgy of cast iron means it would weld better with S/S wire in argon and a lot of preheating. I haven't tried this, but results with ordinary wire are very poor.
