Inverter versus Rectifier
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  1. #1
    Join Date
    Dec 2006
    Location
    Twin Cities, MN
    Posts
    97

    Inverter versus Rectifier

    Okay I thought I knew what I wanted but the more I read and the more I learn the harder it is to choose.

    The bottom line is i want very precise welds in thin material What technology is best for low power applications or does it even matter?

    I said in a previous post that I was building an airplane from 4130 tubing. I probably will never weld anything thicker than 1/4 inch and will probably never weld aluminum.

    The syncrowave 200 has been on my mind and I have not read anything bad about it.

    I want a welder that can have the "Razorblade" weld ability even though I'll never be able to do that. Will the syncrowave 200 have that kind of control?

    Thanks Guys, It's been great learning from all of your expertise.
    Grant

  2. #2
    Join Date
    Jan 2006
    Location
    In A Nice Comfy Chair
    Posts
    15,705

    Re: Inverter versus Rectifier

    I'd like to answer that but i can't..
    i dont know a syncrowave from a microwave..

    but i do know this...
    a good A.C.-D.C. tig machine comes standard with a watercooled set up from the get go..
    has all the right solenoids and hook-ups for gas and water "on and off"..

    footpedals are mandatory in my book..

    and i dont give a crap what anyone says...
    250-300 amps max is nice...
    and after that ..


    its all up to the operator...

    plain and simple..

    ...zap!


    I am not completely insane..
    Some parts are missing

    Professional Driver on a closed course....
    Do not attempt.

  3. #3
    Join Date
    Sep 2006
    Posts
    1,052

    Re: Inverter versus Rectifier

    And the only way to get above the 200 amp barrier on single phase tig so far, is this as far as I know:
    http://www.thermadyne.com/evolution/...9&subcatid=110

    These are new machines.

    Zaps got the best tig machines Hobart has yet to make (it was discontinued I guess). And no invertor has the water cooler built in. (Mine sits outside the machine, hoses everywhere, got to remember to turn the cooler on etc.)

    Miller is close with their xmt series, but it doesnt have ac capabilities.

    This would probably be close to zaps setup but a different color, with some extra bells and whistles.

    http://www.millerwelds.com/products/...rowave_250_dx/

    Oh yea, I like mine, cause its small and light. Garage space is limited so I make decisions sometimes based on what I have room for. If space is no problem, you can get some pretty good deals on the big heavy ones. I hear the transformer machines are cheaper to repair as well.
    Last edited by Doolittle; 01-05-2007 at 10:56 PM.
    Various Grinders
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    When you can get up in the morning, Its a good day.
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  4. #4
    Join Date
    Mar 2005
    Location
    Carrollton GA
    Posts
    2,329

    Re: Inverter versus Rectifier

    You can get higher than 200 amps in single phase, but it requires a bit of effort. You can wire your welder directly into the breaker panel. This means you are effectively using the main breaker as your welding breaker. I have welded at full amps on my dialarc 250 like that. It works, but it ain't the safest way to do things...I am sure an electrician can better explain why...Some shops with the older style higher amp tig machines have their machines permanently wired to the main or to a 100+ amp secondary switch...

    In terms of inverters achieving over 200 amps, if you have two of the same power sources, you can run in parallel (you can do this with rectifier machines also). In theory, you should be able to get close to 400 amps that way (given the max of 200 amps in single phase on each inverter). I am working on this with two powcons, but this is not exactly the most feasable alternative in most situations.

    If low amp control is your goal, you need to look at how the machine is controlled. Both inverters and rectifier based machines state their high and low amp capabilities. Some go as low as 5 amps, some 1 amp. This will be a very important factor for you. I was told by some old wise man with a beard...that always makes it true, right?!...that several range settings is better than one. It allows you to fine tune better, even though it makes for more fiddling with the controls. This is the reason you sometimes see old tig machines with 3 ranges settings, where stick-only machines have only 1 or 2. It makes sense, though. Cutting the range into pieces means finer control at the low range than at the high range.

    For your purpose, a quality machine in either category would probably suffice, but focus on the low-end capabilities when you shop.
    Last edited by smithboy; 01-06-2007 at 11:17 AM.
    Smithboy...
    if it ain't broke, you ain't tryin'.

  5. #5
    Join Date
    Oct 2006
    Location
    Ca, USA
    Posts
    5,241

    Re: Inverter versus Rectifier

    I may be wrong, but I dont think the power supply being an inverter or rectifier/transformer has much of a bearing on what quality welds you can make on thin material. As far as the machine is concerned it's more about how low you can dial the machine down to and how stable it runs at that low setting, regardless of the method it uses to deliver the power to the torch.

    How I see it, it's really the preperation of the weld joint, proper selection of filler and gas, machne settings and *most importantly* the skill of the operator that make a great weld, especially on thin material. I will say that, in my experience, as far as machine features are concerned, having pulse and knowing how to use it does help alot on the thin stuff, at least with MIG anyways.

    Alot of the large old machines, except the Synchrowaves with optional boards, don't have nearly the features and adjustments of the new inverters, although I have seen some awesome welds made with these old machines, despite their only basic adjustments (operator skill, again ).

    We use pulse MIG at work on thin aluminum and it allows quality welds to be made easier and with more control than without the pulse. I weld most stuff equally good with or without the pulser on, but it takes alot more concentration without pulse. I'm not sure how that translates to TIG, but I will find out soon. More about that later...

    The bad thing about the big old rectifier/transformer machines for someone working from home is that they use too many input amps on single phase. Not many of us have 100+ amp 230v breaker available to run one of those monsters. Plus they can weigh 300 to 500 lbs and take up as much space as a top-door freezer! Some of these old TIG machines are as big and heavy as a truck-mounted self-generating welder, like a Miller Bobcat and such. I seriously considered an old heavy machine and could probly have got a good deal on the old Dialarc HF we have at work that nobody uses anymore, but I dont have that much power to run it and didnt really want to use up that much space in the garage either.

    The big attraction to the big heavy machines for me was the possible substantially lower cost of one of these old machines and probability that it will work just fine despite age and previous use and likely continue to work fine for many more years and possibly not cost alot to fix if it does have a problem. The other positive is they make alot of amps and that many amps in an inverter costs BIG $$$$! Of course, without the juice at the fuse box to run one of those at full power, the extra ouput capacity isnt of much use...

    I looked at all options and finally decided on a Thermal Arc ArcMaster185 ACDC. I brought it home this weekend . I'm working on setting it up with a home-made water cooler and once that is done, will be putting it to use soon, hopefully, and see how it goes.

    This machine is surprisingly small- weighs about 40 lbs and is about the size of a personal computer unit. It is amazing how much stuff they can pack into such a small, light package! I was even more amazed how small and light the Miller inverter 375 Extreme plasma cutter my neighbor just got is! It is really, really tiny! Inverter technology is really something . The technology isn't cheap though... The new Thermal Arc machine alone, without torch, cables, etc, was almost $2000 and the 300 amp model I looked at is over $3000 by itself. :| I thought long and hard before spending that much for only 185 amps.

    On the plus side, the new TIG should run fine on the puny 30 amp breaker we have in the garage. It might pop it at max setting, not sure, but my calculations suggest it should be good for up to 160 amps without trouble, maybe more. That should be good for most stuff I intend to weld with TIG. Might have an issue with aluminum near 1/4" and not anticipating being able to weld thicker than that with aluminum, but I have a MIG setup for aluminum I can use for that if I need to. DC MIG seems to use less power than AC TIG and the MIG is an inverter too (an older PowCon 300SM with pulser and a Cobramatic/Python wire feed setup).

    The new TIG machine has the pulse, slope, freq balance, pre/post flow, etc. adjustments that the old Dialarc at work doesn't have so I will play around with those and see how they go. I'm use to using pulse MIG on light aluminum production at work and various small projects at home and have the hang of the adjustments so I'm anticipating using the pulse feature on the TIG on some light aluminum or sheet steel here at home sometime in the future and see how I like it.

    If you have the space and the juice to run the old monsters and want to save some money or need a machine that can run at high amps and heavy use, an old machine is probly a great choice! For me, the inverter made the most sense, despite the big hit to my wallet. I'll see how it goes here soon....

  6. #6
    Join Date
    Jan 2006
    Posts
    1,745

    Re: Inverter versus Rectifier

    A Miller Dynasty makes razorblade welds easy. I was talking with one of the Miller reps. He said the difference between the Dynasty and the Synchrowaves was so great, that if you learn to weld well on a Dynasty, you will likely not be able to weld on the Synchrowave. The Dynasty welders can maintain the point on the tungesten much better than any other welder.

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