AC vs DC Welder question

[EdK]

I am looking to buy a generator and have followed the story line on how an engine-driven welder makes a lot of sense - particularly from the perspective of being a fellow TBNer who'd like to learn welding to support my habit. However the timing is such that I'm presented with the opportunity to latch on to a particular Miller Legend 301 where the price is right and the 1800 RPM operation is appealing for lower noise power generation and for hopefully longer equipment life.

I've noticed the bulk of the of posts from experienced TBNers/welders is to get DC stick capability. What is one giving up by not having AC?

Thanks, Ed

 

[gsganzer]

The reason for most people preferring DC is because of the smoother and more stable arc. I have a machine that has both AC and DC capabilities. The only time I've ever used the AC is for TIG welding aluminum. I believe I can still TIG aluminum using DC, but I lose the square wave function that's desireable for welding aluminum.

If you have opportunity to pick up a 301 at a good price, go for it.

 

[SPIKER]

ED:

when you don't have AC then you may not have a generator/welder, you only have a welder. some people like to weld cast with AC, it works for dc revers polarity normally for cast. and alum is nice for ac.
the welder/generators will have 120 volt recpticals that are 1800 rpm, and some have the idel lock function which has less load output of 120 vac, and 240 vac! the miller welder/gen sets are pretty nice we have 2 of them.

Mark M /forums/images/graemlins/ooo.gif

 

[rdbrumfield]

If you need a generator and have the need for a dc welder which is by far the best for stick welding, my only question is what are you waiting for if you have found one at a reasonable price.

 

[poorboy]

I have an old Ac tombstone and I would gladly trade places with you. I'm sure on the ocassions that you would need AC you could borrow one.

Patrick

 

[EdK]

Mark I'm not sure I understand your comment. Sure there are 240 & 120 volt generator outlets for AC power delivery but there is no provision for AC welding with this machine so hence my original question.

I have read many TBN posts stating that DC is preferable for most all stick applications but I just wanted to be confident I was not making a decision I would later regret as I do not now have much at all in the way of welding skills and experience - just justification of a generator purchase.

Lastly the machine looks to be a good deal but even at that they don't give them away so I didn't want to be ramping up the stick learning curve only to find the machine having limited application.

Thanks, Ed

 

[jimg]

Hi Ed,
Im thinking you'll not miss AC at all. If you look at the Miller site youll see the Legend cant be fitted up for AC TIG. So that rules out efficent Al welding. As someone else mentioned you can weld Al w/ DC but its not efficent and youll go thru electrodes pretty quickly. I also doubt youll be able to to weld very thick pieces. I suspect also you dont get many controls w/ this welder so smoothing out AC electronically isnt going to be an option. It can be fitted to MIG weld also. That might be handy in a pinch.

I see youre in NH. Unless this deal on the Legend is going to go away soon you might consider taking a welding class at the tech school. I did that prior to buying a welder. It was $$$ very well spent. If you want to know more drop me a PM. jimg

 

[EdK]

Thanks for the input. I'm already familar with the welding curricula at the local technical colleges - even know a graduate. I plan on taking a course or two down the road. Its' the time thing!

If I was ever going to get at all serious about TIG I would look into a Miller Syncrowave 180 or perhaps a Thermal ARC 185 inverter. At the moment I'm just trying to make reasonably sure not to shoot myself in the foot with regards to my options with stick. I do have a need for a generator as well as have a lead on the Legend so you can probably see where I'm coming from. I value the advise to get some instruction as is often mentioned in posts toward aspiring welders but if I pass on the Legend I might have to buy a generator anyways and then I'll be sure not to have an adequate welder!

Thanks again -- Ed

 

[jimg]

Hi Ed,
I think youll be happy w/ the Legend as a stick rig and perhaps MIG. As for TIG I think the inverters rule the roost. I have one and its amazing what these can do in such a portable pkg. It would be a good mate for the Legend. BTW is it going to be stationary or mobil (on a wagon)?

The great thing about the welding class is that you get loads of hands on w/ many different types of machines. It helps you see the strong/weak points of each type and what would work best for your situation. I wound up w/ an inverter b/c its portable and multiprocess (Maxstar 200). At the time Miller hadnt announced the Dynasty. Otherwise I would have gotten one of those.

If you do get the welder you might also want to consider an oxy/gas rig. I use mine at least as much as the welder. Its lots easier then sawing and it can also be used to heat, braze and weld.jimg

 

[_RaT_]

Ed, just recently I went through this. The Legend looks ideal and gives up little to the 301G.
I too like the reduced RPM generator. It obviously does not have quite the wattage ability but I would easily sacrifice that for an engine running at 1800 RPM. The Legend uses only the Kohler as the Onan does not have the electronics to utilize the various the RPM's needed for the generator/reduced weld output and full weld output. After going through all the work of learning about what Miller and Lincoln had to offer, I am delaying my purchase. The AC is for the most part not needed. If I did TIG, I would rahter have a invertor TIG unit with much more control over the current/voltage characteristics. I had originally looking at the Miller Trailblazer but after lots of investigating and talking to folks, not to mention checking the units out myself, the comparable Lincoln was a much nicer unit. I am instead going to be getting a dedicated Mig machine for now. For engine driven welding, the Legend and it's 1800 RPM is very nice. Rat...

 

[EdK]

Now oxy acetylene is the one piece of welding gear I do have and have had for 25 years. I really like gas welding which is probably why I've always been attracted to tig - even if I've no legitimate purpose for it!

 

[jimg]

Hi Ed,
If you take the class youll be miles ahead b/c you start out gas welding. I enjoyed gas welding and like you am drawn to TIG b/c its a cleaner finer process. Its also very versatile. I think TIG can be just as all purpose as stick just not as fast. If speed doesnt matter then I would pick TIG. The results are far better. Theres no slag to chip or contaminate over welds and it doesnt put off all the smoke, fumes and spatters.

LOL! Our intro class had a one night TIG overview. Of all things the instructor chose Al to weld. Needless to say he spent a lot of time changing electrodes. Almost everyone drew Al up on the Tungsten...only a little touch down would do it too.

 

[SPIKER]

I prefer welding SS and AL with the TIG for sure, different tungstens , ever try SS with an AL tungenstin? lol. one was in the mach, all ready ground down so I thought it was SS red tungesten. needless to say it didn't hold up too long. anyhwo way my hands shake anymore I'm using the tungsten for filler material as much as I am for welding! /forums/images/graemlins/frown.gif

it is almost caulming welding SS with tig though, as long as you're back don't cramp up from some ackward setting postion!
Mark M /forums/images/graemlins/cool.gif

 

[Yankee]

I like TIG too, and agree that if you don't need speed it can be regarded as all-purpose for fabrication. For repair, though, it has one drawback in that you need clean metal. Fortunately, CC power supplies can run stick for dirty and rusty metal.

Yankee Bill

 

[jimg]

Hey, theres always a bright side to everything...Id look at that shake as the door way to a distinctive weave. /forums/images/graemlins/smile.gif

 

[jimg]

Right, TIG needs a clean start, However, many stick rods need the same. Only those rated for greasy, rusty, dirty parts will really give a good weld. I think the flux on them is designed to float out the garbage that wasnt cleaned up and to dig thru it as well. I suppose you could set the dig up on your welder but I wouldnt trust the resulting weld exc for noncritical joints. In all the repairs Ive done theres not been a time I havent been able to clean it up prior to welding. Ive always had the luxury of not being under a time dead line. /forums/images/graemlins/smile.gif

 

[EdK]

I noticed Rat came to prefer the Lincoln after thoroughly checking out the Miller Trailblazer and Legend. Mind filling me in on what it was that won you over to Red?

You other guys are inspiring me to hold out for TIG!

Ed

 

[jimg]

If you decide to go w/ a generator and welder (separate pieces of equip) have a look at the inverter boxes. The Miller Maxstar family is pretty slick. You get stick and TIG in the same box, portability and loads of control.

 

[EdK]

The only thing that has me a bit worried about the inverters is the reliability issue. It is a pretty expensive thing to start with and I'm hearing typical repair costs on the order of 50% of the purchase price. /forums/images/graemlins/shocked.gif

I know they're efficient with respect to power consumption however I already am set up with pretty heavy service in my garage to support a transformer unit. So the only downside to one of them would be the ongoing cost of the juice. Given my hobby orientation I don't suppose that would really be a factor as is quoted for inverters in production shop environments.

Do you find the Maxstar heavy enough for tractor attachment type welding?

I suppose reasoning this out fundamentally would permit me to get a generator-only unit now, saving the fine details of the welder issue for later - perhaps even after I've had the opportunity to taker a class or two. If that's the case then so much for the kill two birds with one stone aspect of the welder/generator.

Thanks, Ed

 

[jimg]

Hi Ed,
Understood about repair cost. They (Millers) do come w/ a 2yr parts/labor warranty. I think this should cover you pretty well b/c anything thats going to let go will likely happen in the warranty period....well usually. That said I asked my instructors and it was their view that todays inverters are very robust. In fact the Linde, Miller and Lincoln inverters at the school have required as much repair as the old transformer types....nearly none. So, the technology and design must be pretty good by now. Those units at school are heavily used too. During the normal yr theyre running between 8:00 and 9:00 (day and night classes) every day. If youre really interested to know you can give Jack (dept head) a call some time and ask him. He's a really nice guy and is very willing to answer questions.

Given your intended use I agree that power consumption wont be an issue. However, portability might be. If you can get your tractor/implements close enough to your shop w/o moving the welder then go w/ something less expensive (than an inverter). However, if you think you'll need it in the field or you want better controls (arc, gas, etc) the inverter might be what you want.

Yes, my Maxstar is plenty. Its a 200a welder but a 300a model is also avilable. I *think* the spec on the 200 is something like 3/8" plate in a single pass. However, thicker bits can be welded nicely multipass.

I dont want to come off sounding like inverters are the only solution. A good engine driven welder would certainly be portable (in a truck or trailer) and most larger units are multiprocess. I suppose it really comes down more to what you want to do w/ it and where. I'd drop by a MaineOxy or Merriam-Graves and grab the Miller/Lincoln catalogs. They contain lots good info. Probably the best source of info is the sci.engr.joining.welding news group.

Taking the intro class will help greatly in making an informed choice. The knowledge and hands on w/ differing brands and machines is invaluable. The experience you gain can't be replaced by any amt of reading.

jimg