mig aluminum

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Im going to purchase a mig machine to build an aluminum boat or two or three who knows. I will use it for other things but mainly aluminum. I dont want to purchase somthing Im going to kick later, and i dont want to purchase somthing that only the best welders can utilize. Is it worth going with pulse or will somthing like a millermatic 252 with spool gun work or will a millermatic 212 work. I would eventually want to make welds similar to what tig looks like. Any help is appreciated. I dont have to purchase miller i just have more info on miller.
Reply:Personally, the surface 'design' on a weld doesn't mean much to me.  Evenness of the toe lines, flat and evenness of the face, proper equal leg length of the fillet, proper throat depth, root penetration, fusion and wetting of the toes are far more important than making cute little semi circle shapes on the surface.  If you want it to look like tig, then tig it.  If you want to make aluminum mig welds that look like tig, get a Lincoln Powermig 350MP with the pulse-on-pulse feature.   It's alot more machine than most anybody needs though.Definately get a machine capable of running a push-pull gun if you truely want to mig alot of aluminum.  A spool gun is fine for occasional use, but the little 2 lb rolls of wire not cost effective to use in volume.  Spool guns are also alot more uncomfortable to do alot of welding with than a gooseneck push-pull gun.The MM252 with push-pull gun would be my minimum machine choice for doing alot of aluminum welding.  The MM350P was my choice and I'm quite happy with it.  It has the power to weld anything in it's path and the duty cycle to do it over and over all day at a fast pace and not skip a beat.  We used these at my old job doing very high volume aluminum production and the machines all performed flawlessly and proved to be very reliable.  I liked welding with them so much I bought one for myself.The pulse feature is very nice but not needed except for thin sections.   If you will be regularly welding 1/16" or less thickness, the pulse is the way to go.  It's very difficult to mig very thin aluminum without burn through without the pulse.  Normally, sections 1/16" and less are the domain of tig welding rather than mig, aside from pulsed mig.  There is very little difference between the price of a MM350 and a MM350P, so you may as well get the 350P model with the pulse, for small amount of money it costs, if you decide to go with the 350 at all.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:thanks for the info, I was leaning toward the 350p maybe ill be blowing through aluminum scrap for the next week or month or year it shouldnt take to long
Reply:g-man, DesertR'33I use the MK Python and Cobra push pull wire feeds on the Lincoln 350 power MIG and that model of power supply includes the pulse mode and pulse with pulse modes as well as about a dozen more.  I also use the Miller Dynasty 300 DX with a cold wire feed TIG gun and I'm not about to give that up either..... but:If you want to build a welded boat and you haven't done one before, I'd recommend that you consider the economics of the wire feed and power supply prior to purchase.   Since the 350 and a push pull wire feed will cost 5-6K$ US, it seems likely that you'd need to be working the welder 8-10 hours a day to return that investment anytime soon?  If you will keep your day job, and build when you can- I doubt you'd see the difference in a 350/push-pull and a 250/spool gun wire feeder.A welded aluminum boat is 15-20 hours of layout/cut/tack/fit/prep/handling/sanding/buffing/grinding/setup... to one hour of welding.  So a 1000 hour skiff is maybe 50-70 hours of welding depending on the design and your experience.   If you don't already build (?) I'd recommend you spend more on preparation for the vast number of manhours hours in the way of quality tooling to do those many jobs and economize on the welder -for at least one or two boats.Ten dozen clamps is worth more to a first- time/ one-off builder than a Ferrari welder because the compromises in fit and prep are more difficult to overcome than an 'old Ford 150 welder'.  Most new builders won't spend the 2,000.00-3,000.00$+ for clamps that are really needed, but they envision a super welder as a valid expense in their ramp up costs.  After the first dozen skiffs you'll have reason to go push-pull, but not to start out.  Push-pull and multifeatured power supplies are nice, I own them and I'm not saying that I'll move to a spool gun, but my next skiff won't be "my first rodeo" either.  I fully agree with DR'33 that the push pull gun is a nicer tool, feels better and I can weld 'better' with one compared to a spool gun; but the percentage of time you'll be welding as a one man builder is too low to justify those machines initially.What size boats, will set the scantlings and that will set the power the welder needs to sustain to fuse those hull elements.  So the diameter of weld wire and power supply come from knowing what is in the boats you'll build- if you don't know that you have to rely on guessing- not the most effective planning method known in boat building.I completely agree with DR'33 if you want a weld to look like TIG , use a TIG torch and be done.  If you're going to build welded aluminum you'll want a TIG torch on all the corners, MIG simply is not agile enough to do those seams well enough to bother.  MIG will work, the welds will hold, but the full time builders stop a few inches from the corners in many cases to leave that for a TIG torch.  The least obvious fact of welded aluminum boats is that thicker larger boats are far easier to build than thinner smaller boats.  Don't start with much below 18' in 0.125" sheet using 0.035" wire or your learning experiences will be long and frustrating.   It is harder to MIG weld 0.080" by five or ten times than to weld 0.160" sheet, so a proportionally smaller, thinner boat is much more difficult to build compared to the 18'-24' class using 1/8" up to 1/4" plate. As you will learn, if you continue with your plan, welds scale down to a point and then continued shrinking of the weld in proportion to thinner parent metal is a real challenge.Also; welding practice is too often done in 4" strips of 'bench set' or down hand horizontal coupons: waste of time.  If you want to practice boat welding you'll need to make a decent 12" -16" long uphill/downhill/overhead and below your knees weld that is consistent, in speed, bead, start and stop.  If you don't practice these before you build you will have less value when you're done ["finished boat"] than the raw metal value delivered from the metal supplier.Of course you'll have to start with the 4" strip welds to get some idea of MIG, but if you don't keep going until you have uniformity for longer, multi-position welds (?) your first few boats may be a bit rough.Here are a few of mine.rowing dory, rough metal copy in 0.100" and 0.080" of a gunning dorya little closer in to see the double wall hull and endsa 14'er for the First Mate one of the family day boatsDaughter's open 24' w/fishing crew this skiff was recently modified (again) and will be posted to that thread when time providesa  25' footer,  we built in the 80's, shown here in Eldred Passage, Kachemak Bay, Ak, she's pushed by a 454 Merc/IOand a 30" long scale model in 0.060 and 0.080" with two Honda 150's that are solid aluminum.The first few welded boats are the most challenging so here's wishing you well with your project(s).Cheers,Kevin Morin
Reply:Go and get yourself an OTC DP 400 (pulse), very simple to use.  Perfect welds, sweet as.....Or the compact version is the 270.Last edited by Apples; 07-06-2010 at 09:06 AM.
Reply:There is some very good and useful information here. I would pay attention. I build mud boats and when I started I did it all with a spool gun and some tig where needed. I bought a Millermatic 350P and am in love with it. My only info if is based on what you can afford. If you can afford the 350P by all means go for it. If you can't go with the spool gun. If you go with the spool gun and later down the road weld with a pulsed mig it will sure give a greater appreciation.Yes I can tack it for you.    I know that won't hold but that is what you asked me to do.  Millermatic 350P XR Aluma-Pro push/pullMillermatic 185/spool gunMiller Dialarc 250 HF Water cooledThermal Dynamics Plasma