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Old 03-20-2013, 07:12 AM
Portable Welder Portable Welder is offline
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Default 2" Aluminum Weldment looking for advise on Equipment

I have the Cobra Mig 260 Push Pull system which is from MK products,Its approximately a 2003 model.

I just quoted a big aluminum job to weld 2" thick aluminum plate together with several ribs to be welded under the plate that are 3/4" thick x 14" tall.

Ive been looking at the welder that OTC offers that does pulse mig but isn't a single phase machine, so now I've been looking at the miller.

Miller has the 350 MPA and the MM 350 pulse, I just wonder how they will stack up to the Cobra that I already have.

The fact that the miller machine puts out more power should help for cooking into the 2" aluminum plate where my 260 amp machine is going to require a ton of pre heat.

So who has used both and is there a big difference between the Cobra verses the Miller

And who has used the 2 millers, The 350 P verses the 350 MPA.
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Old 03-20-2013, 08:22 AM
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Shade Tree Welder Shade Tree Welder is online now
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I moved your post to a new thread, hope you do not mind, but I think you
will get more mileage out of it separate from Lucky Jack the Thief's push pull
thread...
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Old 03-20-2013, 08:26 AM
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Cannot answer you question directly. I have a MM350P and a 30A spoolgun
I did weld up some 3/4" aluminum plate and the machine did not even
break a sweat. I was reparing cracks and has to grind our a deep V to
get good penetration. Did in 3 passes. I have not every had the chance
to run a push pull gun. The vast majority of my business was steel, I saw
more cast iron than aluminum.
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Old 03-20-2013, 11:27 AM
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LKeithR LKeithR is offline
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Quote:
Originally Posted by Portable Welder View Post
...I just quoted a big aluminum job to weld 2" thick aluminum plate together with several ribs to be welded under the plate that are 3/4" thick x 14" tall.
You quoted this job without knowing for sure how you're going to weld it? Hope things work out for you.

We've never welded anything that thick but I can tell you for sure that 2" material is going to be a huge heat sink, especially if you're working with larger pieces. Your 2" material is more than 2-1/2 times as thick as 3/4" and I'm willing to bet there is some incremental increase in the amount of heat you're going to need to weld it.

Another thing to consider is if this is a big job and you're going to be welding continuously at or close to maximum amperage you'll need a good high duty cycle. Can't help with the actual welder selection; all we have is a 250 amp Lincoln...
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Old 03-20-2013, 11:36 AM
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allessence allessence is offline
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I have never used a Miller Mig for any production..

I have ran Yeti which is a 500amp machine with 380amp continuous..

I don't have a push/pull gun but if the job is going to pay well enough adding that to the deal would be a no brainer..

The OTC looks like nice machine.. You are gonna be generating some serious heat.. Hope you have a water cooled gun and the heat reflective gloves..
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Old 03-20-2013, 12:26 PM
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Quote:
Originally Posted by LKeithR View Post
You quoted this job without knowing for sure how you're going to weld it?
That is not really all that uncommon...
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Old 03-20-2013, 12:32 PM
FabberMcGee FabberMcGee is offline
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It could help to use Helium for a shield instead of Argon to make your fire hotter. I've done that many times with tig on heavy aluminum castings and it seems like I used it with mig a time or two, but that was long, long ago and the memory circuits are in need of repair. Worth a try.
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Old 03-22-2013, 07:46 PM
Portable Welder Portable Welder is offline
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Lkeith R. I know what my machine will do, One of my first jobs when I bought it was to weld 4" x 4" x 1/4" tubing to chunks of aluminum that varied in size from 7" x 7" x about 8' long to bigger chunks that were 7" thick x 24" wide x
5' long.

So I know what it takes, I have ( 5 ) 100lb. propane tanks and 10 bottles of oxygen included into my price for pre heat, I'm going to have it clamped down to saw horses to hold it flat while welding and so I can run my pre heat from the bottom side. ( Having it clamped to my lay out table would be to much of a heat sink )

I will preheat to 400 degrees before starting to weld.

There are 3 plates to be welded together to make one big plate that will be 8'-6" wide x 13'-4" long.

Then I have to weld the 3/4" plates x 14" tall x the length of the table in both directions to keep it rigid.

There will be stress releiving and machining involved between steps along the way.

So anyway, I'm wondering if a bigger machine will cut down on my preheat enouph to think about buying a more up date machine.
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Old 03-22-2013, 07:48 PM
Portable Welder Portable Welder is offline
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By the way, Thanks Shade tree welding for moving my post, I agree this should give me better exposure.
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Old 03-22-2013, 09:04 PM
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I don't know squat about monster welders.

My money is on Miller 350p.
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