welding thick metal 1" and up

[wireguy]

I have a miller 251 any ideas about welding thicker materials like 1" to 1-1/2" mainly fillet welds. Thinking about going with 045 wire.
I have more confidence in stick welding that I see better penetration but would rather go with mig for the convience.
Either way I will be going with 3 passes.
Is 045 wire to much for this machine?

thanks

[tigman250]

.045 isn't too heavy for that machine, although you will have to run that machine at it's peak for that application, so allow lots of cool down time! what gas are you running? generally you want the fillet to be half the thickness of the thinnest material being welded, so welding 1" plate you want a 1/2" fillet. you can get about 1/4" fillet with a single pass running .045 so a 3 pass weld would be enough on 1" plate but go to 1 1/2" and you would be looking at at least 6 passes to get the desired result.

a multi pass Mig weld is my second most favorite weld to do it's a close second to an alum Tig weld. when done properly it is one of the most eye pleasing things on earth in my opinion. the thickest i have had the pleasure to weld was 2" with a 10 pass weld, i wish i had a digital camera back then so i could post it, all i have is some 35mm pics if you want to stop in i would be glad to show them to you sometime! take some pics to post when you're done!!

[wireguy]

Tigman,
I am running 75% Co and 25% argon
What kind of motion do you use?
I love to see some of the cap beads they do on pipe welding but can never get mine to look like that.

Should I just stay with .035 since everything is set up right now and I dont have to wait till Monday to get the wire,liner, contact tip . I guess what I am saying is there any advantage to going to 045 if I have to wait on duty cycle of the machine.
Thanks

[tigman250]

Tigman,
I am running 75% Co and 25% argon
What kind of motion do you use?
I love to see some of the cap beads they do on pipe welding but can never get mine to look like that.

Should I just stay with .035 since everything is set up right now and I dont have to wait till Monday to get the wire,liner, contact tip . I guess what I am saying is there any advantage to going to 045 if I have to wait on duty cycle of the machine.
Thanks

it would be weldable with .035 but you still need the machine wide open weather you use .035 or .045 and no need to change liner just wire and contact tip. if you will be doing any amount of this i would recomend that you get a roll of .045 just to keep your weld size up there. your machine is capipble of it although it's the upper limits.

when i made alot of multi pass welds i was running a 455 Lincoln (wich had a 100% duty cycle) using 95-5 gas and .045 wire. never made any motion just pushed it straight and steady, to get the beautiful welds you have to be almost "robotic" in your movements, any little jerk or hiccup will show up in the weld. good luck!

[wb5jhy]

Wireguy

I guess it depends on how much you have to do. If it's only a few inches or a foot or two then just stay with the .035 you have. If you have quite a few feet to do then maybe you save a little time by using .045. I like the fact you will have a little better arc density for penetration with the .035.

While doing some practice pieces last week I made a real nice looking 1/2" wide cap with only .030 wire (only about 3 inches long).

[TOMWELDS]

1 - 1 1/2" plate in 3 pass's?

[aametalmaster]

I welded the angle iron legs to my work bench which was 1 1/2" plate, with my MM185 and .035 wire with 75/25. Clearly beyond the scope of the machine but it was all i had and it worked great. But as already said allow some machine resting (cooling) time in there...Bob

[MMW]

I have a MM250 (10 yrs. old) & have run .045 bare wire with 75/25 gas & also run a dual shield wire with 75/25 gas, no problems. I use dual shield wire indoors or innershield wire outdoors on thick stuff, never bare wire. I was always taught (no facts to back this up) that you do not get as much penetration with bare wire as you do with a shielded wire. From my experience I have no reason to not believe it.---MMW---

[Danny]

Jim,

with 75/25 as your shielding gas, your best approach for this thick material would be either an .035 or .045 all position gas shielded fluxcore. 75/25 and solid wire will work too. However, you 'll have to have the machine seting pretty high, which is going to put you into a globular transfer. Meaning a lot of spatter and a very fluid puddle that will be limited to a flat or horizontal T joint. The spatter can be adressed though by lightly coating the basemetal with anti spatter. However, if you're going to go the solid wire route on this and can get the joint into the proper flat or horizontal position as required, I'd actually get a bottle of 90/10 and set the MM 251 into spray transfer mode. The MM 251 has an excellent spray arc, resulting in a weld that is virtual spatter free.

[MAC702]

1 - 1 1/2" plate in 3 pass's?

Fillet welds. You might be trying to picture a full-penetration butt weld, maybe?

[tigman250]

rember to scale the material before welding that thick plate has really thick scale on it.

[Engloid]

If you don't preheat it, the welds will likely crack right down the middle.

[Fishy Jim]

Engloid, how would you recommend doing the pre-heat, and how do you know when it's hot enough to start the weld?

[dyn88]

ahh somebody piped up about pre heat. You will need it, also a slow cool is neccasary(just use fiberglass insulation and cover the parts overnight).Preheat should be no less than 350 degrees, and as a rule of thumb 1 hour of pre heat for every inch oof thickness, before welding. Sounds like a lot of work, and people do get away without it, but all this preperation will ensue a quality weld, and no failure. Stress relief after weld is always recomended. Also peening your welds between passes is also recomended.

[wireguy]

spray transfer mode

Jim,

with 75/25 as your shielding gas, your best approach for this thick material would be either an .035 or .045 all position gas shielded fluxcore. 75/25 and solid wire will work too. However, you 'll have to have the machine seting pretty high, which is going to put you into a globular transfer. Meaning a lot of spatter and a very fluid puddle that will be limited to a flat or horizontal T joint. The spatter can be adressed though by lightly coating the basemetal with anti spatter. However, if you're going to go the solid wire route on this and can get the joint into the proper flat or horizontal position as required, I'd actually get a bottle of 90/10 and set the MM 251 into spray transfer mode. The MM 251 has an excellent spray arc, resulting in a weld that is virtual spatter free.

I can position it so I can always weld flat. "set the MM21 into spray transfer mode" how do you change the machine to do that?