mig welding keggles?

Ok, I'm buying a mig welder. Would like to mig weld up my own keggle, and maybe some for my buddies too.

What size wire & approx amperage would you weld a keggle fitting on?

And...how do you get the backing gas into the keg, so as not to get the nasties on the backside? A second tube off the bottle flowing while you are welding, or just fill it up, and let it rip? Weld it upside down (big hole down) or big hole up?

 

Use 100% argon shielding gas. A second tank and regulator are best for back-gassing. I use aluminum HVAC tape to secure the back-gas hose and create a pocket for shielding gas.

Use .030 308LSi wire at a setting just higher than you'd use to weld material as thick as the keg walls (about 18 ga sheet metal). Most MIG units have number and letter designations for the power and wirefeed settings, so I'm not going to venture a guess for your particular machine.

 

perfect. thanks yuri

 

I've had very good luck with not welding the inner seam at all. I cut the hole slightly smaller than my coupling, then use a jig to pull the coupling through from the back. The jig is kind of shaped like a mushroom - the rounded part starts smaller than the drill and ends up at full width. The stem part fits inside the coupling, so the coupling can be pulled through behind it.

The end result is that the coupling is wedged very tightly in the hole, and the metal at the edge is flared out slightly around the coupling. Then I just weld around the outside over that flare, and all is well.

 

That sort of makes sense, but do you make the jig, or buy it? it's really a flaring tool, that also pulls the coupling through the hole, right?

 

I prefer a helium/argon mix for stainless.... But we've all seen the awesome work that Yuri does, so I can't fault anyone for following his advice.

 

I've always had a tough time on thin (read: sheet) metal. I'd assume you'd point the gun mostly into the fitting, as the difference in thickness is great. Do you guys TIG or MIG? I'd prefer a TIG for this, but buying a MIG for general use.

In the past, I used the 75/25 mix of argon/co2, and straight argon. Never noticed much of a difference on plain steel.

 

I prefer TIG for stainless work, and I use my TIG machine for most general purpose work as well. I have a little MIG unit that I use for small jobs. DO NOT use any CO2 in your gas mix for stainless.

 

Yuri, why use the high chrome 308 wire, why not use 304L or 316L wire as it is a little easier to use on stainless - stainless welds. We normaly use the 308 material for carbon to stainless welds on piping and equipent.

 

i just welded my keggle this past weekend. I have a Miller WeldPak 3200 HD. I used 0.30 wire ( its the most readily available). I took alot of trial and error to get the settings right. Eventually I used the recommendations from a welding website. Voltage set to "D" and wire feed speed set at 7.5; 100% Argon. I back gassed with the same gas but quickly ran out. I found that if I had a tight fit between the hole and fitting then no back purging was needed. I'm pleased with my results but boy did I gain a huge respect for those who can weld as well as Yuri!

 

When dealing with unknown alloys, 308 is the most versatile. I use 309 for the type of dissimilar metal work you're talking about. That's not to say that 304 or 316 won't work...308 is just a safer bet. I've used 316 on kegs without issue.

 

This is definitely true. The trick with welding a thick piece of metal to an extremely thin one is to weld quite a bit on the fitting and then gently push the puddle onto the keg. You almost never even let the arc touch the keg. Also, forget about running a bead. You'll make this work by making one round weld and stopping for 15-30 seconds, then making a second weld next to the first with a little bit of overlap. In order to get the fitting hot enough, the setting will be too high for the keg. If you try to run a bead, it'll work for a minute, but the keg will overheat and you'll blow a hole in it... or you'll move too quickly and the fitting won't be truly attached. This is a challenging weld for someone with little experience. I'm no professional, so I'm counting on others to dispute anything incorrect that I've stated

 

shafferpilot has it about right. Focus the arc about 60-75% on the thicker material, and work the puddle onto the thin stuff. Especially when MIG welding thin material, stitch weld, rather than running a continuous bead. It's a little easier to run a continuous bead when TIG welding.