Transformer tig machines

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I am looking into buying a tig welder. Currently I am looking into purchasing a miller330a/bp.  But any brand would be fine for me.Other than the huge size and heavy weight of this (and other transformer type tig welders), and 100+amp 220v 1ph service requirement for full amperage use, are there any drawbacks to this unit?I currently just MIG and AC stick weld, but am looking to TIG, and DC Stick weld also. Aluminum welding capability is a must.The price is approx $700 including miller watercooler, water cooled torch, and foot pedal. It is a mid 80's vintage unit with high freq, model#330a/bp. Can I realistically get into any other units that will HF weld aluminum and have 180+ amps of power and a water cooled torch for less than $750.Thanks,Brian
Reply:I like a trasformer type for reliability. If you have the power available, I would go for it. I am not familiar with that unit.
Reply:As the owner of 2 P&H machines that were built in the 60s, I still don't see the attraction of the new inverter units.  Newer machines have a lot of bells & whistles, but we were TIG welding long before the bells & whistles were thought of. They might be cost effective in production situations, but I don't see the cost/benefit equasion for an occasional user.What I do see in the new inverter machines is a lot of repair potential for the manufacturer.  How many of them will be around and functioning even 20 years out is an unknown.Appreciation Gains You Recognition-
Reply:Brian,If my memory serves me correctly, the 330A/BP is not a square wave unit.  Welding aluminum with an older sine wave machine is harder than a modern square wave unit.  There are several excellent transformer square wave machines out on the market. A square wave machine should make it much easier for you to weld aluminum.Regarding inverters, in addition to size, weight, and power consumption, their biggest advantage comes into play when you are in the AC welding mode.  With an inverter, you can vary your AC balance over a much wider range – most AC inverters will go from 10% to 90% - a big plus when you are welding a dirty casting and need more cleaning action.Another advantage is the wave is so square, that the HF is only needed to ignite the arc.  It is not needed to re-establish the arc when it goes through the zero point of the wave.  So, once the arc is started, the HF goes off.  All conventional transformer machines will have the HF on all the time when welding in AC.  Now, that can play havoc with a phone system, computer, or even an on-board computer in a car.  If those aren’t issues for you, then don’t worry about it.Another advantage is the ability to vary the length of the AC wave.  Conventional machines are fixed at a 60 Hz wave.  With a typical inverter machine, you can vary the frequency from 20 to 200 Hz.  At the higher end of the spectrum, it focuses the arc to a point, concentrates the heat and makes it easier to get the aluminum up to temp start welding and get finished.  End result is less heat input and less warpage and distortion.  It also makes a 200-amp machine seem like a bigger unit.The final advantage is to use 2% thoriated or ceriated tungsten sharpened to a point for welding aluminum and steel.  With a point, there is less arc “wandering”.However, with inverters running around $2200, that is a big jump from the $700 you can get the Jeff
Reply:For about $1300, HTP (www.usaweld.com) has an inverter TIG that'll run on either 110 or 220V.  The model is the Invertig 160.  It's also supposed to be a decent  DC stick machine and only weighs 32 lbs.You can DC pulse from 1/2HZ to 300 Hz.  The drawback - on 220V, max output is 160 amps @ 40% duty cycle, 120 amps @100%.  You didn't say how thick the aluminum was that you were welding.  But if you need 200 amps, you definitely will be in the $2200+ market, new, for an inverter unit.  Inverter units are still too new for many of them to have found their way to the used market.
Reply:Ol Pilot, that machine is a DC inverter and would only weld steel.JeffJeff NolandDrive a LincolnDrink a MillerWeld with an HTP
Reply:Well, the first paragraph of the first page of their ad indicates it'll do aluminum.  How well is probably a another matter.  Probably would be better to put the money toward a Tig machine.  I've Tig'ed a lot of 11xx, 53xx and 60xx series AL, but I haven't been really happy with my mig attempts.
Reply:OlPilot, Reread the ad. It says if you don't want the expense of an Ac/Dc machine. Later on it states good for mild steel chromemoly, stainless. no mention of aluminum.Steve
Reply:Yeah, you're right.  Misleading ad, but when I finally re-checked the specs there wasn't a lick of AC available on that machine, so it won't break the oxides.  Their model 201 has AC, but like we noted, it's back to the $2300 range.
Reply:Thanks for the info!  FYI, I bought the machine, a miller 330a/bp, with watercooler.  Now, to find to the time to hook it up and play with it.My job, wife, and house really get in the way of my hobbies