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Dc Tig - Transformer vs Inverter

Mike RzMachine

Cast Iron
Joined
Feb 4, 2007
Location
Utah
I've been welding some steel on an htp inverter tig and i'm wondering if my observation is real or due to some other factor.

when welding dc, does anyone else notice that the arc is more stable and consistent on a transformer machine when compared with an inverter? i remember noticing a difference between an esab inverter from about 7 years ago vs. a miller synchrowave 351, and also my old linde c300. to me it felt like the transformer machines had smooth continuous arc with some inertia where as the inverters felt like the arc was a series of rapid sparks that would dance around.

does anyone else notice this? is the effect less noticeable when comparing different inverters?

Mike
 
Actually, my experience has been the exact opposite.
I have, side by side and used every day, a Miller Syncrowave 250 transformer, and a Miller XMT 304 Inverter.
Both used 95% for DC tig welding on stainless steel.
The inverter is smoother, more stable, and gives better welds.

It also is smoother and easier to use when I hook my wire feeder up to it. I have an old Regency Transformer power supply for Mig, and I switch the exact same wire feeder between the transformer and inverter- no contest- the inverter is miles ahead.

It works great for stick, too.

My guess is that what you are experiencing is the HTP, which is a small import that is "value engineered". That means they cut corners to make it cheap. An XMT 304 probably runs twice the price or more, and is built a bit better.
 
i remember noticing a difference between an esab inverter from about 7 years ago vs. a miller synchrowave 351, and also my old linde c300. to me it felt like the transformer machines had smooth continuous arc with some inertia where as the inverters felt like the arc was a series of rapid sparks that would dance around.

Mike

Is the esab inverter American built?
 
i think the esab was the 160 amp ac/dc unit that came out around 2001 or so. i don't know where it was built.

i was reading more about it, does ceriated tungsten show any improvement for inverters? i'm running down around 30-50 amps welding thin chromoly (tried some .020" very tricky with this setup, .035 was fine, but the arc wasn't stable enought to control the puddle well).

i think it is very possible that this particular welder isn't as smooth as the bigger machines i've run. i'll have to ask around to see if i can find a place to try a miller or thermal arc inverter.

thanks,
Mike
 
I knew of a pretty picky kind of guy. He told me that when he was shopping
for a welder he described a smoothness issue that you describe. He tried all
kinds of machines and finally bought a new Miller Syncrowave 350. Can't blame
him for his choice.
 
i was reading more about it, does ceriated tungsten show any improvement for inverters?

It is supposed to. People buy these expensive inverter machines and then stick
cheapo Chinese Cerium electrodes into their torches. Doesn't make sense. I also
think the outcome of a weld job depends more on the guy holding the torch than
what the torch is connected to.

Holy cow, I brought out my Miller catalog and what did I see. A Dynasty 700.:bowdown:
 
A quality inverter like a miller dynasty takes the cake on any old transformer machine. Smoother arc, more options like built in sequencing, high speed pulsing, much more adjustment on the ac side too, the new ones a have a few different wave forms as well as Hz adjustment up to 400Hz! All the mean while drawing far less power, and taking up less space.

I have a 200dx, and a 300dx, gonna do whatever I can to get a 350dx in here with all the latest and greatest bells and whistles. Absolutely love these machines over the old transformer units.

Here are a couple nice SS welds I did recently, 2.5" O.D., .065" wall:
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Soda cans:
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Courtesy of my trusty 300dx and a bunch of practice.
 
An inverter will always have a better arc than a tranformer based machine (Unless its an Aerowave). Its a matter of physics.
 
Physics aside,
I have used sync 250, dynasty 300, lincoln PM300 and a Dimension for Dc tig and the difference is slight at best.

The thing that makes the biggest difference is the operator.
 
just wanted to give an update. i changed electrodes to a ceriated tungsten instead of thoriated. i'm running a .040" tungsten and the same grinding marks that didn't seem to matter on a 3/32" electrode made all the difference. i ended up cleaning up the point with a diamond file after hitting the belt grinder. i was able to weld some .025" tubing with no problems. also weldmold 880 is some fantastic filler to weld with, it flows out and wets perfectly.

arc initiation is now what i'm used to, and the wander is gone. like most problems, it was user error.

Mike
 
I have been using sanders to sharpen tungstens, instead of grinding wheels, for 30 years now, and would never go back.
Its faster, easier, and usually cheaper, especially if you have a sander already.
Tungstens eat grinding wheels, leaving nasty grooves in em. Unless you just have a dedicated grinder for tungstens, you need to constantly dress the wheel, and it still wears out really quickly.

I use a 12" disc/6"x48" belt sander daily in the shop for all kinds of stuff, and grind my tungstens on it daily as well. For quick and dirty stuff, I just use the disc sander- chuck the tungsten in a cordless drill, and spin a quick point on it. I find this works for 90% of what we do. Once in a while, the directional grind on the tungsten is really important- usually on really small tungstens, .040 or so, and on thin materials- and then, I will do a radial grind on the belt sander.
On the disc sander, you get a circumferential grind, so the arc is very slightly less focused and sharp. For most decent tig welders, this is no biggie, but if it is, you use the belt. The belt just doesnt cut quite as fast as the disc, and its a bit trickier to hold the cordless drill at the right angle.
I use Klingspor CS411 sandpaper on both, 50 grit, which is an alumina zirconium (blue in color) abrasive that will sand tungstens all day. We mostly work stainless in my shop, so the cheaper, brown sandpapers dont hold up to every day use- but the klingspor CS411 lasts a long long time, both sharpening and general shop grinding.

I would not consider using the bench grinder, which is 2 feet away from the sander, for most things, including sharpening tungstens, as the disc is better almost every time. You have to have the horsepower- mine is 2hp- and good abrasives, but it works really well when you do.
 
My dad uses the cordless drill as well. Too much trouble for me. I can have a tungsten sharpened before he even gets it in the drill chuck.\

I do use the disc sander as well. Bench if I have to. I think I have a 180 on the disc sander.
 
I use a "Tru-grit" belt grinder... made for knifemakers ... uses a 2" belt and of course they make various grits from super fine to popcorn. I usually use 180 and keep a belt dedictated to tungsten. If I am going to work way back in a ceiling somewhere, I grind a few electrodes
and stick them in my pocket.. I keep a jar of chem sharp in the shop but dont use it too often.... although when I do I like it, just used to grinding them. As to the type of machine... I am very into the Dynasty right now... simply the best machine I have ever worked with in every respect.
 
FWIW, it's easy to adapt a diamond wheel (surface grinder type or Baldor tool grinder type) to a small bench grinder. The diamond sharpens really fast & leaves nearly perfect straight lines running to the point.

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----------------
Barry Milton
 
I use the same setup as precision works at home, and the belt grinder at work. I feel the diamond wheel does a better overall job, but the belt grinder does just fine - and I don't feel bad putting contaminated tungstens on the belt grinder (I don't like that with the diamond wheel).
 
From my understanding

Older welders were made with copper windings on all the coils

on new inverters and transformers they use aluminum windings to save weight and because copper costs too much.

many stick welders are convinced nothing runs smoother than their old engine driven welders. A lot of that is attributed to copper windings verse aluminum windings.

On tig welding I've never been able to tell the difference on anything from precision welding to dirt steel. I've never had an arc I would describe as "smooth" and the only thing I could think of that effects the arc, like voltage fluctuations, arc wander etc are usually attributed to bad grounds, bad leads, bad material, change in gas etc. Not the quality of the arc coming out of the machine.

so really I'll run with whatever. That being said I prefer the modern transformer machines both for all the controlling issues and the weight and size. And this goes for when I purchase new machines for our facilities and my home use.
 








 
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