Gas for MM251 Usage? spray arc and/or versatile?

[Teeps]

Well, I'm picking up my mm251 with spoolgun on Tuesday, dual cart, two regulators.

So I need to put two nice big tanks of gas on her, and grab some 4043 wire.
I'm thinking around a 140cf-ish tank of Argon, for aluminum (and eventually for a tig machine I understand it goes fast on tig.) Unless its even cheaper to fill a larger tank. I won't need a ton of gas up front, but down the road I'll regret going small, as I already have.
As long as it still sits on the back of the welder without tipp'n her over, lol.

I know for a fact, I'm going to want to see what this thing will do on spray arc, for anything from 3/16's to 1/2"
Just because

I'm thinking maybe 98 AR / 2 O2 will be the ideal gas for spray arc on the MM251? or will the extra amperage capability allow for a cooler, possibly more versatile gas?
Or would 92 AR / 8 CO2 (C8)
Or (C5), or (C10) be better?
Or is the O2 the way to go for ideal results? (which I know is true of the MM210)

I may still weld 1/8th to make a welding table, and carts, and the like, which I assume you still need to short circuit, and I assume you want to go back to C10 or c25 for that. (or pull out the old 120 volt machine, heh)

If I could get away with something that does both spray, and other processes, then that's what I'll purchase on Tuesday.

I'll be dropping quite a chunck of change on the O/A tanks as well, so trying to make the most efficient decision. Not to mention make up my mind, before the dealer tries to just push off whatever they have in stock as being better.

Thanks in advance!!!

Don

[cope]

I believe that C-15 or C-10 would do everything with your MM251 but the experts might disagree.

[Teeps]

Thanks, Yeah I'm leaning towards C10, and ARGON right now.

I think Linde probably carries both in various sizes, I guess I'll find out next week!

[Danny]

Don,

For steel,there really is no single gas mix that produces excellent results in short arc and spray transfer. C-15 would come the closest. However, c-25 is going to be a better short arc gas, and 98/2 or C10 are going to require lower machine settings to produce a good spray arc. I know from experience that short arcing with c-10 on the MM 251 results in a poor quality arc, and a weld bead that doesn t wet out very well in comparison to C-25.

Personally, to have the most optimum performance in short arc and spray transfer on steel, I prefer to use two different gas mixes. C-25 for short arc, and 90/10 or 98/2 for spray transfer.

[Teeps]

Thanks Dan, I really appreciate your insight.

I already have C25, but it is a smaller tank 40 cf if I remember correctly, I will probably leave it on the little welder, but have it available for short arc on the mm251 for those occasional needs. I'll upgrade to a large spare eventually.

So if you had to pick between C10, or 2% O2, which would you use the most?
sorry for the loaded question, but with the MM251, when would you need the O2? certain materials, or just on the thicker end of materials requiring more heat? Like spraying on 1/2?

I'll probably end up having all of the gasses mentioned, just prioritizing for Tuesday, thanks!

It's going to be a good Xmas this year!!!

[joebass]

If you are going to be spraying any stainless I would get the O2 mix. I think that HAWK uses 92AR / 8CO2 with his ALT.

[Danny]

Thanks Dan, I really appreciate your insight.

I already have C25, but it is a smaller tank 40 cf if I remember correctly, I will probably leave it on the little welder, but have it available for short arc on the mm251 for those occasional needs. I'll upgrade to a large spare eventually.

So if you had to pick between C10, or 2% O2, which would you use the most?
sorry for the loaded question, but with the MM251, when would you need the O2? certain materials, or just on the thicker end of materials requiring more heat? Like spraying on 1/2?

I'll probably end up having all of the gasses mentioned, just prioritizing for Tuesday, thanks!

It's going to be a good Xmas this year!!!

Don,

You should be able to exchange your 40 cf bottle in for something like an 80 cf and only have to pay the difference in price between the two bottles. For me, the 80cf works well on my MM 175, MM 210, and MM 251.

In my situation, I tend to favor using 98/2 for my spray arc gas. my #1 reason being what Joebass has already mentioned, which is that 98/2 allows me to spray arc steel and stainless steel. My second purpose is that 98/2 allows me to spray arc with my MM 210 too. However, if you're looking to strictly spray arc steel, 90/10 is going to produce slightly better pentration across the width of the weld bead then 98/2. 98/2 tends to penetrate slightly deeper to the root of the weld then it does to the legs. 98/2 and 90/10 are both going to have no problem producing sound welds on 1/2" steel. Well, that is a long as your machine settings and technique are correct.

[Teeps]

Thanks alot Dan,

I'm definately picking up some 98/2 (Oxy) , I appreciate your insight and experience.
BTW the miller GMAW books shows AR/O2 mix for all spray arc, except on Aluminum.

One other clarification, when you say 90/10 (with better penetration) are you refering to C10, or 10% Oxy ?

I also have a 40 cf of C10 and I will upgrade it later.

Thanks,

Don

[Danny]

Don,

90/10 = C10

To the best of my knowledege 5% is the highest level that oxygen goes to in a gas mix.