Hi Everyone !!! I have been watching this site for a while now and I figure this is the One. Like a lot of New Guy's to welding I have a lot of ????????? I have a Lincoln Mig Pak 15 as "They" call it. I believe it's a 30/175 amp welder 220 volts with 75/25 gas. and .023 wire. I have had it for about a year or so and have done some welding. BUT, I am having some Problems welding exhaust pipe. I am using a mix of tubing everything from stainless/aluminized steel and mild steel of different thicknesses. I can weld it together no problem, But I am working on a Hot Rod for the last 6 years and I want Professional looking welds on my exhaust. I have cut up a bunch of pipe and I have been practicing for awhile but I seem to be getting what I would call oxidation. I think I have the burn through under control but the oxidation has me in fit's: mad: I used to have my regulator set at about 25 psi but the guy at my parts store told me to lower it to about 15 psi because the higher presure was causing too much turbulence ??? Anyone have any Good tips ??? I have looked at all the tutorials Thanks, Jack
- Thread starter Jack62440
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shenion
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You regulator should be calibrated for LPM or SCFH. If it is PSI, then it does not have a flow control.
10LPM or 20SCFH is standard.
Best would be to add a flowmeter, then you can have a real reading fo the flow.
If the metal is aluminized or galvinized, it is best to grind it off as it will gas up during the weld. Galv fumes are and irritant also, so make sure you have good ventilation.
10LPM or 20SCFH is standard.
Best would be to add a flowmeter, then you can have a real reading fo the flow.
If the metal is aluminized or galvinized, it is best to grind it off as it will gas up during the weld. Galv fumes are and irritant also, so make sure you have good ventilation.
malcolm
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Technically MIG is using an inert gas like argon, and MAG exactly the same thing but using a mixed gas like Argon/CO2.
For stainless normally a gas mix of Argon with a very small amount of O2 tends to be recommended (though a small amount of CO2 works OK). Not sure what would happen if the CO2 was raised to 25% in terms of finish, but it wouldn't be best for weld embrittlement.
Where do you get the corrosion? Is it the outside or reverse of the weld? Is the stainless pre-used or new and how are you cleaning it? (Stainless that's been heated can be even more of a pain than new stainless and worse still if there's any carbon about) Also is the any chance of popping a photo up for us to understand the problem better?
For stainless normally a gas mix of Argon with a very small amount of O2 tends to be recommended (though a small amount of CO2 works OK). Not sure what would happen if the CO2 was raised to 25% in terms of finish, but it wouldn't be best for weld embrittlement.
Where do you get the corrosion? Is it the outside or reverse of the weld? Is the stainless pre-used or new and how are you cleaning it? (Stainless that's been heated can be even more of a pain than new stainless and worse still if there's any carbon about) Also is the any chance of popping a photo up for us to understand the problem better?
I have the gas set at about 15 scfh I snapped a couple pics. but it's kinda hard to make anything of the welds. I found out about zinc last year when I repaired the rear fenders and reshaped the wheel wells with brake line. 
Sore throat for 3 days. Now I grind anything suspect. Otherwise I use a wire wheel to clean things. I weld in the garage with a fan off to one side and vent it out the side door so there is no draft on the weld. My crappy welding has been holding me up for too long. I have been thinking about pulse 
the pipe and clean it up with a flap wheel on my grinder. Trying to stay even on the weld while going around the pipe is too much for me. maybe if I do 3/4" at a time will work. Jack
Sore throat for 3 days. Now I grind anything suspect. Otherwise I use a wire wheel to clean things. I weld in the garage with a fan off to one side and vent it out the side door so there is no draft on the weld. My crappy welding has been holding me up for too long. I have been thinking about pulse the pipe and clean it up with a flap wheel on my grinder. Trying to stay even on the weld while going around the pipe is too much for me. maybe if I do 3/4" at a time will work. Jack
shenion
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You might try 20SCFH, that is what most use.
I found 0.025/0.6mm wire difficult as you weld so slow with it. Also the wire speed will be high for anything over 1mm/20ga. I found it is much more sensitive to torch length than bigger wire.
0.030/0.8mm should be easier and more consistent. You might also look at setting up various jigs so you can rotate the work and keep the torch position/angle more constant.
I found 0.025/0.6mm wire difficult as you weld so slow with it. Also the wire speed will be high for anything over 1mm/20ga. I found it is much more sensitive to torch length than bigger wire.
0.030/0.8mm should be easier and more consistent. You might also look at setting up various jigs so you can rotate the work and keep the torch position/angle more constant.
The last while when I was practicing my gas bottle was almost out, but It was still showing pressure. Today I went and filled up the tank and the weld is Alot cleaner and you can hear the difference. I think with some more practice I should be able to get the results that I want. Thanks Alot !!! It's been a Gas 
Jack
Jack 