AM91Camaro_RS

alright, i am by no means that great of a welder! i will say that up front! however, i am building a new set of headers and need some advice. i am using a nice mig...not sure what brand it is, it belongs to work. i think its a name brand (its blue, i'm thinking either miller or lincoln). anyways, it has digital controls on it and everything. so, here's the problem...i am getting some heavy puddling. this is 18 guage steel that i'm welding. i tried a few settings and i think i ended up with 13.5 volts and like 130 IPM wire speed. if i try to slow down to burn in more, it burns through the pipe. if i try to go a little faster, it puddles heavily. it is all stuck solidly...theres no doubt in my mind about the strength of the welds but they look horrible! i'm using argon (pretty sure, i'll double check that) as a shielding gas and i think its a .035" wire. if anyone can give me some advice, i would really appreciate it! also, what "patterns" work best for a nice looking bead? thanks again!

ede

use a GTAW (tig) machine, or a torch attached to a stick machine.

AM91Camaro_RS

ok, the welder is a millermatic 250mp. it is using a 75% argon, 25% carbon dioxide gas. can anyone give me any advice that i can use with this machine?

swerve-driver

What do you mean by "Puddles heavily"?
What are the headers made out of? (stainless, mild steel, etc..)

cany ou provide a photo of the problem?

S-D

AM91Camaro_RS

puddles heavily as in big, thick welds.
18 guage mild steel.

i was messing around with some scrap a few minutes ago and got it working a little better. i dropped the wire speed considerably and am at 13.7 volts. i figured out that part of the problem was my technique. i was "staying in the puddle" too long. i started moving a little faster to stay a little more ahead of the puddle and the beads look a lot nicer. but, i'm still open to any ideas!

laiky

thats a great machine! it doesn't get much better as MIG welders go. Your problem is likely that the wire is way too thick for 18 gauge. I would switch to .023" wire. The problem is that the .035 wire requires too much heat to melt. Your dropping wire speed to compensate so the wire burns off in blobs instaed of a smooth continous beads. The proper settings (ballpark) should be printed on a chart some where on the machine or in the documenattion. I have a MM175 (small unit, simple too) i can weld exhaust tubing easily and really well. The Big Miller will do very well.

If you want to learn more about welding go to :

http://www.millermotorsports.com/mbo...isplay.php?f=3

That board is sponsored by Miller and frequented by some extreamly knowlegable and friendly people.

AM91Camaro_RS

thanks a lot laiky! haven't looked at that site yet but do you know anything about setting this machine up for doing aluminum?

laiky

typically they use a spool gun with 100% argon as the sheilding gas. I believe the unit your using has an additional gun port specifically for a spool gun. Although most don't reccomend it i believe you can just set up a spool of alluminum wire in the standard gun. the spool gun isused because there may be a problem pushing the softer alluminum wire through the long cable of the standard gun.

swerve-driver

laiky hit it right on-
S-D

355gta

All migs are 75% argon and 25% carbon dioxide. I am a welder and I weld 22 gauge sheet metal with .035 wire all day. They diameter is not the problem. I think he needs to play with the welder some more on scrap metal to get it right. Also, try vertical welding. It will lay down smoother and you can cover the area faster.

laiky

so i take it you mean your running continuous beads on 22 gauge sheetmetal?? With .035" wire?

By the way, c25 mix (argon co2) is not the only gas used in mig welding, strait co2 is also used although not as common and tri-mix CO2/argon/Helium is reccomended for stainless steel.

Bottom line is that .035 is not the correct choice for light gauge welding, it may be possible but it is much more difficult than .023 or even .030. Typically .035 is used for thicker metal.

83 Crossfire TA

iTrader: (2)

Um, the 251 is much better… there’s a reason why miller would release a second machine with the same power output to replace one that they already had…

No. The 250/251 don’t even come with a .023 drive roll, only a .030 and .035, and even if you got one you’d find that the machine has power curves and wire speed tracking optimized for the .030 and .035” wire, and most people will have better results with the heavier wire.

what’s actually happening is that your not putting enough heat into the weld and at the same time depositing too much wire. Instead try getting the gun in closer, increase the feed speed and possible even increase the power a little, then weld/travel much faster.

ede

i know some people think all mig welding is done with c25 but fact is it isn't, some people thqat don't know better use 95-5 and 98-2. some people even thing "mig" is a legitimate welding term.

83 Crossfire TA

iTrader: (2)

C25 is the most commonly used mig (gmaw, mig is actually a correct term, it’s just not the technical term for the welding process), but as you need a hotter weld in mild steel the % CO2 in the mix goes up, and sometimes even some O2 or He is added. In the industrial world in a lot of cases they use straight CO2, which is cheap and gives you a lot of heat, but is not as clean to weld with (more spatter, but what the hell does a welding robot care). When you get into special grades of steel you’ll see CO2 + a flux core specific to the job, this is how they lay down the 409LSI that is used in a lot of car exhausts now. Otherwise on a smaller scale, assorted “tri-mixes” are usually recommended for mig welding stainless, but in most cases unnecessary.

For the most part, most people here could get away with just C25 for MIG on mild steel and stainless (unless you’re doing food or aerospace grade stainless work and then you wouldn’t/shouldn’t be taking welding advice from someplace like here), and straight argon for aluminum and most TIG welds. Some He is nice to have around if you find that you need to put some extra heat into a weld, like if you wanted to TIG aluminum using DCEN.

355gta

Today at work I looked at a chart inside our millermatic 251. It said for 18 gauge steel using .035 wire you should set it to 15.5 volts and 135 IPM. Although that may not be perfect it is a good starting point. And yes, I weld continuous beads on 22 gauge sheetmetal using .035 wire. It is very difficult but I do it all the time.

83 Crossfire TA

iTrader: (2)

I tend to think that miller's wire speed recommendations tend to be on the conservative side… usually a little more wire speed and a little more travel speed can really make a difference with the appearance of welds on thin metal.

Rob Wade

Are you pushing or pulling the gun? As said earlier, try doing your welding in the vertical down position. You will get a much flatter weld. Start at the top pulling down and do approx 1/3 of the tube. Rotate and do another 1/3 then rotate again and finish. I think you'll like it. Sorry I am some what late reading this and you have probably finished by now. I would have tacked it together and then tig'd it also.

AM91Camaro_RS

i'm pulling the gun. i haven't even been doing a 1/3 or the tube without rotating it, i don't think. just been doing small sections then rotating. i think that i was actually welding it too cold. i haven't tried anymore of the exhaust pipe yet but i've been welding on some thicker steel and i turned the voltage way up and got much nicer welds. but, yes, i did think about tacking it together then having it tig'd but i didn't want to shell out the money for that cause my local guy that does tig isn't too cheap! (as i'm sure most aren't)

Rob Wade

Not trying to be a dick but I think if you do the tack and pay to tig deal, I think you will be way happier with your finished product. If you save cash on someone else welding it but aren't happy with how it looks is it really worth it? How much do you have out of pocket for the weld up kit and will you be pissed at wasting that money to have them look like sh-t? Just a thought.

ede

you push gas, drag flux one of the very basic rules of welding

AM91Camaro_RS

cool. thanks! i really need to take some welding classes but i never have.

Rob Wade

That is 100% correct. BUT in this case I guarantee you will get a better looking weld pulling a vertical down. Just so you don't think I'm being a dick, I ran my own Midas muffler shop for 14 years and now am a tool & die maker that mostly does the welding/fabricating portion of our machine building. I have built tons of custom exhausts/headers on street rods/race cars/show cars. I still do the odd nice piece on the side. Try the vertical down @ 17V and approx 330 wire speed. Go 1/3 then rotate. Practice on some scrap first and get your hand speed correct. I would still tig them though. Hope I didn't **** anyone off.
PS those speeds are on our miller 300 w/ .035 wire

jack_sparrow

iTrader: (1)

Just my two cents, but I think everyone here is being very open and no one is getting pissed. At least that's the way I am seeing/reading this. I've found that i work best with pullign but my welds have never been pretty anyway. Just lots of practice.

Brett