.... following on from 3 mm plate welding thread.
0.8 mm wire was mentioned and it go me thinking...... the wire is acting as a fuse and will melt when a certain current is reached; 0.8 mm will take
1.77 x more amps than 0.6 so my theory is that the smaller dia. wire is limiting current and hence the ammount of heat being put in.
sound about right?
guess I need to get some 0.8 mm (and some extra tips to be sure). 
I use 0.8 wire at work on everything from 1mm to 10mm 
I used 0.8 wire to make my
manifold-5mm flange and 2.5mm
tube.I have had no problems with it
at all.
Andy
I use 0.6 for everything upto 5mm, although with the thick stuff I do have to warm it up a bit first, biggest thing that improved my welding was
getting a cheap pair of mole grips, welded a bolt onto the top of it and the took off the rubbish spring earth clamp, bolted it onto the metal mole
grips, can now hold stuff together as well as get a good earth.
Cheers
Rich
I've certainly found 0.6mm to be better on thinner steel, so I suspect you're right.
There is one small flaw in your logic though - mig actually works by melting the wire when it touches the `pool` - if it is melting before that then you are trying to use `spray` transfer welding - which suggests your current is too high , or the wire feed is too slow .
quote:
biggest thing that improved my welding was getting a cheap pair of mole grips, welded a bolt onto the top of it and the took off the rubbish spring earth clamp, bolted it onto the metal mole grips, can now hold stuff together as well as get a good earth.
Another thing in the mix if not mentioned is what gas are you using ?
At home I use 0.8 wire and argosheild light with no problems from car bodywork up to 5mm, never had to try and weld anything thicker.
CO2 gas.
... so how can I tell if a) current is too high and/or b) wire feed is too short?
I reckon I am pushing the 120 clarke to do two pieces of 3 mm mild steel so I am on max amp. setting.
mu wire feed is 7/10 - I thjink I did have it on lwer setting but the wire kept melting at the tip.
hmmmm......
Well my experience as been the difference between argoshiled light and Co2 is night and day for ease and quality of weld.
See what others think but if you have plenty of welding in front of you then a change of gas would be well worth it.
CO2 gives a dirty weld, argoshield is a lot better, but use some antispatter spray with CO2 and it does improve things.
I have a 151te, it welds everything very well after I changed the earth lead to something substantial and got a decent clamp. The correct stuff is not
that expensive.
My friend got a 100te, it was absolute rubbish, he was struggling to weld a little plate so I popped over assuming technique was at fault, it was the
welder itself!
With lower end welders try and keep the lead as straight as possible, also has the wire rusted over the winter, if so discard along with the liner as
this will not help.
I also sometimes find 0.6 wire with a 0.8 tip allows me to wind up the speed and current together, less chance of it bunching.
Regards Mark
Using co2 only, restricts the arc length meaning the welding settings will only work in a narrower range,change to argoshield for much better results.