I've got a Lincoln SP-250 MIG, had it for almost two years. I'm finally getting it set up so I can get going on my twins and other projects. Any who, no operating manual with it, so the question, what pressure of gas do I want to run to the machine? I've got Bluesheild Ar/CO2 mix, running .035 wire. Just gonna be welding mild steel, nothing fancy at this point. Any help is appreciated.

 

i dont remember for sure but experiance and logic tells me that you should run about 10-15 psi but i could be wrong i rarly pay atention because i do it all by feel.

 

About 20psi for that size welder.


Tim

 

On a mig it is not pressure but flow you have to have a flow gauge. It should flow about 16 cfm.min. Mild steel only needs co2 . c02 is cheaper than argon. Keep the cup nintey degrees to the work or u will get porosity (bubbles) in the weld.Set the wire speed and the amps so it sounds like bacon frying. PM me if u need more info.

 

isn't the flow rate something like 25 to 30 SCFM?
What is your Ar/CO2 mixture?
It also depends on what technique your going to weld. First time I saw spray arc welding it blew my mind. but talk about lay a thick bead, fast.

 

Good call, thanks, my flow gauge is set to 20 cfm, not psi.

Thanks

Tim

 

We run 25cfm on 75/25 on a miller 251. Never had a weld porosity issue if the tip wasn't held at 90 either...Clean metal and no wind makes for good mig welding

 

Have you gone to Lincolns web site you should be able to download a manual for your machine..

 

Standard for us is 35-40CFM. Just started some endurance tests on a new contact tip design, up to 750 minutes of welding!! Using a slick pipe welder and a trolly to make it a little easier.

 

Got that, didn't see anything for what flow/pres. to run.

Not sure on the concentrations, label just gives Ar/CO2. Its Air Liquide Bluesheild 8. At work we used the Almig gas, which labeled concentrations, not this one though.

I also picked up a pressure reg., not a flow reg. Do I need the flow reg., or can I make it work with what I have?

 

Converting the pressure to a flowrate isn't bad, need information about the gas lines and nozzle to get accurate flow rate. If you just got the P reg and can trade it for a flow reg I'd do it.

 

If you look at my post you will see I said 16 cfm min. That is minimum.

On pipe if you do not stay at 90 degrees to the work it will go bad on ya. If too much angle is used on plate, the gas will pull air into the shield and then you get to grind.

 

Using only co2 in a weld is a weld I would not trust.

 

I have never had a porosity issue if I dont' hold to 90. I have used slightly more gas and slightly less. I have never used all CO2. That could be the reason he says hold 90. I can get away with welding in the wind if I turn the gas up higher.....Shielding it helps. Experiment with welding on something that doesn't matter. You will find the spot where you don't have enough gas...I have never had a weld break. I made a trailer and the metal itself broke before my weld failed. That is the only thing I have ever had break and it was because I was on a really rough road and my friend was making the trailer jump. The welds all held fine. I was told on my guage to use 20........I put it at 10 to 15 now and it works just as good. I am not welding rockets together though...just trailers.....

 

that makes a big difference..If you hold to far away you can get porosity.