Thread: A stupendously mediocre return to bad welding!

Hi folks.

It's been a long 30 years since I last mig welded anything, back then I used to finish the odd job here and there I could be trusted with, so nothing that would ever be seen by the public. Or anyone else. Ever!

I'd go to the machine, look at the dials, check the wire was feeding, forget to attach the earth, forget to check the gas and generally produce bird poop all over the place. However, on the right day, with the wind in the right direction, my head working forwards not sideways, I could produce a decent looking weld.

I retired a few years ago and I'm now the proud owner of a huge man shed with a welder in it, so I've been out there all day building a storage rack for metals and plastics, a new lathe is arriving tomorrow and my old mill will get moved in there as soon as possible. Where was I? Oh yes, so, I'm out there welding away, happy as Larry getting used to things, dialling in the settings and everything's going ok, except I seem to be creating a large amount of soot. I don't remember creating soot in this volume before, but I've forgotten more than I ever knew. I'm getting good penetration, I've sawn up a couple of bits and etched, the bead is acceptable, not beautiful, but I'm getting a decent mound. I'm getting a nice visible puddle which I can play around with, I'm getting a nice rainbow from the bead edges. My gas (100% argon, that's all I've got on hand) is up to a decent volume, no pin holes or voids and it's definitely not flux wire. My technique could definitely be tweaked with some time behind the trigger, but even spots are creating a large sooted area, I'd say half an inch radius from a seconds worth of crackle. I'm definitely frying eggs and bacon, not banging saucepans together, it actually sounds really lovely and the results are ok, there's just lots of soot.

I've looked at a few tubes and they don't seem to create so much, could you kind people let me know what I'm getting wrong and point me in the right direction?

Many thanks.
Sorry for rambling. (First Speckled Hen of the night)

[edit] I should have mentioned, this is 'easy machine, easy weld' steel, I don't know the number. And It's been thnner-ed, then put on a Scotch Brite wheel and thinner-ed again, so it's pretty clean.

Hi Scrunfundle.
We are all allowed to forget things as we get older, OK

Excess soot can be caused by:

1.) too long of an arc length, either by operator stick out, or excess voltage.
2.) Not enough weld energy, increase wire feed speed, or drop down a size in wire to increase current density.
3.) Incorrect direction of travel, you’ll always want to use a push for aluminum
4.) Incorrect Gun angle, next time you are playing around with some scrap, vary your gun angle, you can actually move the soot from one side of the weld to the other just by changing gun angle.
5.) Travel speed too fast, which doesn’t allow sufficient breakup and removal of the outer oxide layer.
6.) Insufficient gas flow coverage, do you have a way to check flow at the nozzle? Never trust what the flowmeter or regulator reads, the only way to know for sure is to check the flow at the torch

Check list before you start welding:

• What gas are you using? Argon is great for aluminium - Not so for steel! It makes the arc too cold
• What flow rate? Try around 14 LPM
• Do you push to shield ahead of the MIG weld?
• Do you pre flow to make sure the starts are shielded?
• Any leaks in your gas delivery system? How old are those gas supply hoses?

I have some MIg welding notes,posted as a Sticky somewhere on the Forum.When I find them I will edit the link for them back in this post .

EDIT; Here Tis < https://www.woodworkforums.com/f160/...-collins-97286 >

Hopefully they shall be of use to you.


Grahame

First thing I thought was the gas type- need an argon/co2/oxygen blend for steel. Pure argon for aluminium/stainless mig. The 'cold' graeme mentions is due to a lack of ionisation of the 'reactive' components of the gas- Co2 or oxygen. Argon does this to a lesser degree.
Pub trivia- MIG and MAG make up the GMAW (Gas Metal Arc Welding) process. MIG is a process with an Inert gas (ie argon for aluminium). MAG welding uses an Active gas (eg argon.co2/oxy for steel).

High gas flow rates can draw air into the weld area and lead to contamination. Same as a cracked gas hose can draw air in like a venturi kind of thing.

Material cleanliness is also important. Remove coatings, get back to bare metal, and if you can use a cleaning agent- acetone or even one of the non chlorinated brake cleaners / pre-weld prep sprays -I've used a chemtech brand one, and it is acceptable.