how important is frequency control to TIG aluminum?

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I'm thinking of someday investing in a TIG welder. As a hobbist I wouldn't need much but I wouldn't buy one that wasn't an AC/DC machine because I would like to be able to work with aluminum. However when I look at what's available there is huge variability in price with some of the cheaper models not having the control over pulse frequency (and probably a whole lot of other pulse stuff). How important are those controls for aluminum and stainless work?
Reply:Depending on the machines range you can seriously change the penetrations of the (ac) weld even with the same amperage. Frequency for stainless (dc)  isn't usually a big concern. You can weld Solid state with no issues.
Reply:Frequency does not matter on DC transformer or inverter welds the same on DC. Frequency makes a difference on ac it allows you to focus the arc
Reply:What shlammed said on the stainless. IMO I would recommend getting it with frequency for penetration and cleaning your welds will show the difference. Some people like the pulse feature others don't and just use the pedal for amp control.Miller 250DX HTP 221 DV AC/DCHenrob O-A Miller 180 MigMiller 150 Inverter   Hobart 10,000 Welder-Generator   Have a good day!!!
Reply:You probably mean AC frequency- well its not realy important, but the AC balance is.For stainless you need DC current. Some machines have pulse dc mode (basicly switching betwen two currents). You also dont need pulse mode, but its usefull on stainless steel and titanium.
Reply:Originally Posted by ravseljYou probably mean AC frequency- well its not realy important, but the AC balance is.For stainless you need DC current. Some machines have pulse dc mode (basicly switching betwen two currents). You also dont need pulse mode, but its usefull on stainless steel and titanium.
Reply:As one of the lesser experienced TIG welders here, Pulse TIG is great, but not even hardly necessary for most TIG welding. If you can get an AC/DC machine, you will be able to TIG aluminum and stainless just fine with a regular foot pedal or torch remote. It's what I've been doing for the past year. I've still only used Pulse TIG once in my life. It was cool as heck but still not something I NEED.
Reply:I have a no thrills lincoln square wave 175 with only an amp adjustment and weld it all just fine.
Reply:Originally Posted by VPTI have a no thrills lincoln square wave 175 with only an amp adjustment and weld it all just fine.
Reply:Frequency adjustment is desirable for arc constriction in some joints but not necessary to weld alum.Pulse on DC for cadence is not something I use. But high speed pulse is a feature I have become dependent on for sheet metal.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Originally Posted by welderjI loved my 175 square wave, it just didn't have the duty cycle I needed. For most hobbyists it would be a great welder.
Reply:I like my adjustable frequency on my dynasty. You can turn it up for small tight beads for corner joints and when a small bead is desired or turn it down for a wider bead.  It's not a necessity for aluminum tig but if your a fair aluminum tig welder it is just more adjustment for tailoring your arc for a desired look.  Best description I've heard is it's like a nozzle on a water hose. Frequency low a wide fanned out bead, frequency high narrow tight bead.
Reply:I also have a Lincoln 175. I'm really glad I started with it. With only the amp dial and polarity switch to worry about, it's allowed me to focus on learning the process rather than searching for the perfect setting to get me through. I've experimented with and learned a lot about tungsten prep, preheat on aluminum, and weld sequence to help get me through. Oh and lots of practice. As I've progressed, I can now understand and appreciate where some of the advanced settings would help. And I look forward to using them on a new machine at some point. Take this suggestion with a grain of salt coming from another novice TIG weldor, but I say get a simple machine with good resale to start. Then in a few years sell it and buy something more advanced if you need to (or just want to).
Reply:Originally Posted by zankI also have a Lincoln 175. I'm really glad I started with it. With only the amp dial and polarity switch to worry about, it's allowed me to focus on learning the process rather than searching for the perfect setting to get me through. I've experimented with and learned a lot about tungsten prep, preheat on aluminum, and weld sequence to help get me through. Oh and lots of practice. As I've progressed, I can now understand and appreciate where some of the advanced settings would help. And I look forward to using them on a new machine at some point. Take this suggestion with a grain of salt coming from another novice TIG weldor, but I say get a simple machine with good resale to start. Then in a few years sell it and buy something more advanced if you need to (or just want to).
Reply:To the OP, hobby guy here and my 2 cents.My Invertig from HTP has ac freq, balance, pulse, and independent amplitude controls. And man, they are awesome to play with.But...I don't weld any better with 'em. In fact it really makes it harder because as you play with 'em as you introduce more variables into the equation.If someone already welds good and consistent (read as: second nature) they could fine tune these settings to end up with results more to their liking.But, IMHO if you can't do it without these adjustments you will be worse off with 'em. At least for a little while to figure out the learning curve to getting 'good and consistent' results on different joints and thicknesses while changing a buncha settings.So a poor man's analogy, this past holiday I played some songs for a group of people using utoob. I almost felt like a DJ!Man, if I only had one of those big mixing boards I could be a REAL DEEJAYIt's easy to see how I woulda totally botched that! Don't get me wrong, it can definitely help. Besides, what's a few more things to learn? I think the biggest variable to answer the question of "how important is freq control?" depends on where your welding skills are at without it.A whole buncha top notch welds have been done (and are still in service) on machines with less variables. Could some of 'em been better? Sure. But it woulda took those weldors longer to learn how to lay down those beads too. And how many hours of torch time did they already have??Soooooo, am I gonna try to trade my machine for one with less settings? NO these are my thoughts, not yours!How do you know the blacksmith's dog? When you hollar at him he makes a bolt for the door!
Reply:Your question was specifically about AC freq., but I'm going to lump that in with pulsing and AC balance.  I weld all day long, and have done so for years, so I'm not coming from a strictly hobbiest perspective, but I could also be considered as a "hobbiest" as I also weld, machine, etc. at home in my converted garage.Whether you could reasonably take advantage of these extra features is in part dependent on what you think you'd do with the welder, once you had it.  For example, I can skip the pulser if I like on thicker materials (say, 1/8" and over).  When welding material that is .025" thick however (which I do a fair amount of), it is a real challenge to do this, and have it come out looking good, appearance wise without a pulser (especially when welding thick to thin).  I could simulate some of what the pulser does, but when working something thick to thin, sometimes there are adjustments you can make that just move beyond what my personal reflexes can do, with regularity and repeatability.  With regards to welding aluminum, again, I think it depends on what you do.  I find that I change certain settings around quite a bit, and just get used to them for whatever project I'm on.  Others, I pretty much set them up and don't vary from my protocols, unless material seems dirtier/ cleaner than usual.  If you are primarily welding moderate thickness material, say 1/8 - 5/16, and making straight welds (not highly contoured), you probably won't really see much benefit to having some of these other settings.  If however, you plan to be welding things with lots of nooks and crannies, lots of transitions between fillets and butts and back again, thin to thick, etc., these settings can start to make life a little easier.I usually recommend the strategy of buying the best thing that you can reasonably afford, assuming that it will do what you will need it to do.  The reason why is this - buying a simple machine, full-well knowing that you will want to buy ANOTHER machine at a later date, just means you are throwing money down the drain.  Welder power supplies hold their value pretty well, but they do depreciate (usually).  The simpler/lower end/older the machine, the less they cost, typically (for the major brands), and the faster they depreciate.  Used Dynasty 200dx welders often sell for dang near retail (though there are good deals if you know where to look).  A used CST 280 does not.  That CAN make for a good deal to you, but only if you don't have to resell it, and then go out and buy the Dynasty later on anyway.  Otherwise, you won't come out ahead in most cases.  If it's just a pipe dream that you are chasing, and say "well I'll buy it someday, but right now I'm too cheap", and if your past history states that you WON'T ever purchase the full featured machine, then by all means, find the best deal on a machine that you are willing to live with.  A welding power supply isn't a status symbol, it's a tool.  That said, get the machine that suits what you do, or plan to do.  There is no right answer, but no one can even begin to give you useful advice until you think you have an idea of how you'll use it.  Much like asking for a milling machine recommendation - without knowing what you plan to do with it, you won't be able to get advice on what you should be looking for.  You could be a hobbiest, but your welding/fabtricating interests could be aluminum boat trailers.  If that's so, then you really don't need anything fancy.  If you are welding something delicate, well that's a different story.Last edited by pbungum; 01-08-2014 at 10:02 PM.Miller Dynasty 200 DXMiller CP-300 with 30A feederHypertherm Powermax 900Oxy-fuel w/Harris torchesScotchman Glide-in bandsawMonarch 10EE latheEmi-Mec Autoturn latheDeckel FP2NC milling machinePro-Tools 105 Bender
Reply:I was using it in a welding business and doing a lot of work. The only times I had trouble was stick welding things like cutting edges and tigging castings. I eventually took the air cooled gun off and put on a water cooled one and that helped a lot. But even then it was just too small for a commercial shop. I came across a square wave 255 and I like that real well too. i sold the 175 for just slightly less than I paid.
Reply:Well, code work has been done for decades with nothing more than amperage control in AC and DC application with nothing more than a tig torch and gas valve hooked up to a transformer or engine driven machine. All the bells and whistles are there to help you get the job done but they aren't necessarily needed.
Reply:Yes, and sailors navigated the seven seas with nothing more than a sextant and a chart, never knowing of or needing GPS to get where they went.MM210TA186TA95sLincoln AC/DC Tombstonegood old Smith torch setup 24v Readywelder mig w/spoolgunSB H 10 latheBridgeport mill6x12 K.O.Lee surface grinderK.O.Lee tool/cutter grinder
Reply:cjowett, the question 'how important' is hard to quantify, because we all come together on a single forum but few do the same work, or in the same material or circumstances.As the replies cover a nice wide spectrum of experiences and needs, they reflect the breadth of those differences of circumstances coupled with the economics of the work related to the poster's projects or needs.AC arc change polarity, alternating the current flow back and forth to the power supply, many times a second and when that happens most AC welders have a high frequency induced on the arc to keep the arc lit, and this was traditionally called high frequency (HiFreq) on the transformer welders. Just so you're in tune with the historic term.Back in that technology the native AC frequency is only 60Hz or 50 in Europe and maybe Oz?  Anyway that 60times-a-second swing from positive to negative meant the arc might stop 60 times in any given second.  So the high frequency of that time was 'on top' of the 60cycles.What you many not as clearly see in the terminology, and why I'm writing it make sure you do, is that now the old transformer 60 cycle output is adjustable. The AC frequency can be turned up to 250 or 500 cycles on some power supplies.The effect on the arc coming off the tungsten is to be able to make the arc core of molten puddle down into the metal different than is possible with the transformer power supply.Currently with inverter power supplies that have variable AC frequency, and digital controls of the power/arc; the AC wave can be changed for different welds where the arc is wider or narrower, deeper penetrating or more surface cleaning and if the amperage surge timer (called pulse but not to be confused with MIG pulse arc) is used then a puddle can be formed that is shaped more for the exact welding circumstances using these feature's contributions together.But even if you had those controls (variable AC frequency, Since Wave Balance, and amperage surge timer)  they could all be 'zeroed' out or left to some fixed value and they would 'leave' you with a limited feature welding power source.If welding skills can be said to be 'additive' or sequential, the hand control of the torch and filler are the basic variables to master.  Lots of people here mention that adding more variables before the basics are mastered slows the progress.So a basic power supply without the arc control features will suffice, if you can afford the more full featured and plan to do welds thinner than 0.125" then you will have provided yourself the arc controls to make those more difficult welds with less effort: once you learn how they work.But learning to use the advanced controls can only happen if they're present in your power supply.I weld with the Dynasty 300 DX and after quite a bit of experimentation I'd have to say I thought the variable AC frequency controls of that power supply model, and following, are as important to the advancement of TIG as the original high frequency arc stabilization.Pulse or amperage surge square wave timers also provide welds that cannot be done without that feature. When combined, arc shaping controls (Variable AC and Sine Wave Balancing) and pulse or amperage timers can provide a level of control that is not possible with other power supplies.If I were repairing farm equipment in the field, or doing heavy iron construction fab I don't think these features would be important because the welds are not as critical to be exact. But I weld boats, and various other aluminum items and these features, once understood are a entire separate way of welding over the older transformer welds.[FULL DISCLOSURE:  I weld with a cold wire feed TIG gun, and use the semiautomatic weld features of the Dynasty to drive TIG at or about aluminum MIG speeds and therefore my remarks are not intended to be confined to dip rod TIG methods. The extremely slow speed of that method of TIG welding brings heat and weld conditions that I never have to consider and does influence my view of the arc shaping controls.]Cheers,Kevin Morin
Reply:all good advice. Thanks guys.