Old Miller Dialarc 250 HF

Ive been offered a complete, though absolutley filthy Miller Dialarc 250 HF welder..stick and tig, Includes the Miller cooler, tig torch,
pedal, leads etc. $200
At this point, I dont know even if it works, but assuming that it does, is this a machine I want to mess around with? Its older of course and I have the identical machine in AC/DC stick only which I rather like, having a very mellow arc, easy to start, etc etc.
Im still hunting around for a cooler for my Lincoln 250 tig/stick machine and this Miller is the price of a good cooler, with all the stuff included.
Do I want to go there or pass on it? Assuming it works of course.
Gunner
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Oh my goodness, come on you dont have to think about this one, it's a very good deal. (Sorry for being so informal, I just know u from lurking). I know you like to fuss around and repair stuff, so the parts themselves are worth it. Think about what this machine has that your none HF dialarc has. Porcelain base with aluminum heatsinks with 4 tungsten contact points ($150 Miller pricing, gotta be at least $75 ebay pricing for people looking to build van degraff (sp?) generators). Complete HF circuitry with high voltage transformer as well as high voltage capacitor, and really beefy inductance coil (air transformer). On top of that you get two solenoids (gas and water) with a nice little standalone circuit board on the gas solenoid to adjust postflow.
You have all the parts necessary to build a standalone HF box. The only thing that has a decent chance of not working ith the HF will be the capacitor ($100 miller, I bought a doorknob cap on ebay for $30). I have fussed with the dialarc, lincoln tig 300/300 and an LTEC (which I currently have) and without doubt the miller had the beefiest built HF circuit. ... And then if the welder itself works ...
But you also have the cooler (which I paid $180, $220 to my door, for on epay and was ecstatic), the footcontrol ($60 epay) and "stuff". You know you have a good deal. Again, sorry about being so informal, and note that I am a newbie welder, metalworker, and poster, but I am a veteran broke-chanic.
Aloha, Russell
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Nice old Stick welder, Sucky TIG. Take the machine, use the coller and torch on your Lincoln and store the power supply in case your other Miller blows up.
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Ernie Leimkuhler wrote:

Ernie, Could you elaborate on "sucky" please? I have been using a Dialarc 250 HF for TIG for quite a while and am pretty happy with it. Mostly I weld mild and stainless steel with it but recently have been welding aluminum with OK results. I am wondering what a newer machine would provide that I am not getting with my Dialarc, and whether it would be worth the money to upgrade... There is a Synchrowave 250 in the paper here.
Thanks, Bob
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TIG welding can be achieved with a HUGE range of machines.
A bare bones DC stick welder, a valve body torch handle and a bottle of argon, are all you really "need".
In the range of machines from a barebones box to the ultimate TIG, the Miller Aerowave, there are many levels.
How new or fancy of a TIG you need depends on what you are doing and how often. If you are doing hobby stuff around you shop and maybe some simple projects for friends, then you are likely to be willing to put up with a less than perfect machine if it saves you immediate cash.
So a simple TIG like any of the old Miller Dialarcs, or Lincoln Idealarcs will be fine, or even a tiny TIG like a Miller Maxstar 140 or 150 inverter. Maybe one of the smaller AC/DC transformer TIGs such as the Miller Econotig, yncrowave 180 or a Lincoln Square Wave 175.
If you do mostly aluminum, then you really need a "square wave" AC capable TIG machine. This includes all the Miller Syncrowaves, Hobart Cyberwaves and later Cybertigs, Lincoln Squarewaves and PrecisionTigs, and many others that date from the late 70's on, including all AC capable inverters.
Sine wave AC machines will work, but not nearly as well, and the high frequency units on really old machines will often be a major source of trouble. Those old machines make fine stick welders with a really smooth arc, but they are just not the best machines for production aluminum.
The ultimate AC welding experiences are AC capable inverters, like the Miller Dynasties, Lincoln Invertecs, Thermal Arc GTSW's and TSW's, HTP Invertigs, and lots of others. AC capable Inverters allow you to adjust the actual frequency of the AC arc from a low of 10hz to a high of 200hz or 500 hz. Running an AC TIG arc at a higher frequency makes the AC arc act like a DC arc, so your tungsten lasts much longer, the weld puddle is incredibly smooth and the arc is quite directional which makes fillet welds so much easier.
DC TIG hasn't really changed as much as AC TIG so if you aren't doing much aluminum then you can likely get along with an older or simpler machine.
Once you get past the squarewave AC thing, you get to the world of pulsers and sequencers. Do you need either? Maybe not. Are they really useful? You bet your ass.
Pulsers cycle the arc output amperage from high to low, allowing much more control on thin materiels and giving a better appearance to any weld. Sequencers allow the control of a "sequence" of events in the machine with a simple button tap. This allows much easier welding in out of position situations where a foot pedal or even a thumb wheel are not practical.
So if I say a machine is "sucky" it is not asying it won't work. I am saying compared to even an older Syncrowave it isn't a great TIG welder. At school we have 6 Syncrowaves of various ages, a Hobart Cybertig 120 from the early 80s, a Lincoln Idealarc 300/300 from the 70's, and a pair of 2 year old Lincoln Squarewave 175's.
Personally I would like to toss the Cybertig and the Idealarc into the scrap heap. They do work, but not even close to as nicely as even our oldest Syncrowave 300. Before we got most of those Syncrowaves from Boeing Surplus we were cursed with Miller 330AB/P Gold Stars. Passable DC TIGs if you have no option, but absolutely dreadful on AC. When they were new in the 70's maybe they were better, but now they are just too beat up and worn out. Bad high freq generators and too many really old parts that do wear out with use.
We still have one of them over in a corner set up with a valve body, flex-head, air-cooled, #3 series torch to be used for scratch start TIG for pipe welding training.
In the world of used machines, Syncrowaves are the best of the transformer machines out there. There is a reason why Miller rules the TIG world.
So, is your Miller Dialarc "good enough" for what you need? That is up to you. What I would suggest is find a place where you can test drive a newer machine, and then you will really see the difference.
On AC TIG, the simple rule stands. The newer the machine the nicer it welds aluminum.
BTW I still believe the best deal in the TIG market today is the ThermalArc Prowave 185TSW, AC/DC Inverter, at around $1750 complete.
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Ernie Leimkuhler wrote:

Snip
Thanks, I was wondering if I should start looking at replacing the Dialarc before my worn out lathe... It sounds like I should try a newer machine and see how it goes. I do a lot more welding than turning.
Bob
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On Sat, 25 Dec 2004 01:59:04 GMT, Ernie Leimkuhler

Ernie..is my big Hobart Cybertig 2 500 DCS a square wave machine? Its got all the ramp up/down yada yada stuff on it.
http://www.metalworking.com/DropBox/hobart-a1.jpg
Its a mid 80s machine as best as I can tell.
So my Lincoln 250 tig/stick is not all that great for aluminum?
http://home.lightspeed.net/~gunner/myshop/running2.jpg
Gunner
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Squarewave vs. Sinewave AC TIG welding, how to tell the difference
Sorry, but I'll butt in to this thread again. I asked the same question with the machine that I have, an LTEC 306N. I was not sure if it was a squarewave machine or not. I wanted to know if there was a way to tell the difference, when welding, if the machine was a squarewave or sinewave machine. However, no one replied and I could not find any threads on a google search, so I just started welding on different machines. I found it is pretty self evident when welding if the machine is a squarewave or sinewave.
On aluminum an AC sinewave machine will give you a wide shallow bead (the profile of an M&M) with a very narrow cleaning band, which barely extends beyond the toes of the bead, if at all. The puddle will not be as shiny and will often include inclusions in the puddle as you weld (little black stuff floating on puddle).
On simple AC squarewave machines the bead will still be a wide shallow bead, however the cleaning band is about twice the width of the bead. The puddle is noticeably shinier and much cleaner with far less inclusions.
I found on the squarewave 180SD and the lincoln equivalent which have a balance pot switch. I could sort of replicate the narrow cleaning band of the sinewave machine but this was with the balance control set for more penetration and less cleaning. The bead itself then is very different it does not look like an M&M but actually has a v-type profile, sort of looks like a spinning top. Of course the puddle is very shiny and has no inclusions.
I have also welded on some inverters, dynasty and the like at welding store previews but did not have enough time to really investigate it. However, I bet I could replicate the sinewave bead by setting the balance control to more penetration-less cleaning and then turning down the frequency to give me a shallow bead. However, this is just a hunch. Of course the puddle would still be shinier and cleaner.
I guess what I'm saying is that AC sinewave and squarewave machines have distinct characteristics when welding, which are easy to see. Mele Kalikimaka Aloha, Russell
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Thanks for sharing the research. It bears out my experiences.
BTW on the Lincoln Invertec 205 (really a Selco Genesis 200 from Europe), they give you 3 choices of wave form for AC TIG. Square wave, Sine Wave and Triangle wave.
I have yet to see anything written anywhere that shows any benefit to a sine wave or triangle wave form in AC TIG.
I would like to play with one to figure out what the effects are.
A lot of the European inverters offer these wave form choices.
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All TIGs were squarewave by the early 80's, as long as they were actually TIG machines, and not just stick welders you can TIG with.

It depends on what kind of life it has lead.
Lincoln built tough high freq. units, but they all need to be maintained.
A syncrowave will out weld it on AC aluminum, but that has a lot to do with the arc control and filtering that Miller uses.
Older transformer TIGs really need a happy high freq. generator to deal well with aluminum.
The manual for your machine should give the instructions on removing, cleaning, reinstalling and gapping the points.
Replacing the high freq. capacitors doesn't cost much (around $50) and can breath new life into an old beast.
BTW Inverters don't use spark gap high freq. generators. They use something called Capacitor discharge high freq. Think of it as a high speed photo-flash, charging and firing. Since they are solid state, they aren't affected by dust buildup. They also tend to cause less RF interference, which is why they are the only machines you can use near medical or broadcast equipment.
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PS The only transformer machine with Capacitor discharge high freq is the Miller Econotig. Which is why they still sell it. The Syncrowave 180, which was meant to replace it, has true high freq so it can't be used in medical or other electronically sensitive facilities.
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