I need a TIG machine. 1/4 inch max will be my envelope, mostly AL so I'd like square wave, no need for water cooling, I have a 60 amp 240V circut but I'd like to be able to run from 110V if needed (I know some of the Millers will do this). Anyone have a specific model to recommend?

You should consider renting one first.
Welding aluminum is very different from steel, so you may not know your priorities until tried. For one, I think you will want water cooling for 1/4", and lots of current. If price is a concern, look for an old industrial unit. They have now come down in size/weight quite considerably, with many automatic features, and many businesses want these new units (and can afford them). So if you have space, you may get a good one for a fair price.

About how many amps would I need to do 1/4"? I'm using this in a garage so that may be a limiting factor.

I would say 250 - 300 amps since welding alu really takes lots of current

Well looks like that idea is out the door LOL.

I just ordered a Miller Dynasty SD with the torch kit from Cyberweld. I stopped by a local weld supply place and they told me it will do just about anything only limited by my circut. They did say that with 1/4" I'll need a water cooled torch like was stated above. Maybe later. Their price as 1k higher than the internet, I wanted to buy local but that was just too much!

I'll let you all know how it works, and even better how it is on a noob like me.

Very nice, I havent tried any Miller unit, What kind of amerpage does it have at max?

http://store.cyberweld.com/mildyn200sda.html

Heres the link.

Says 1-200

I'll just have to adjust my projects to fit as I just don't have the current, or space for a bigger unit.

that seems like a very nice unit, and the price was awesome
it'll be fun to hear how it is to weld with..
Try welding some normal iron first, and getting the feel for adding filler rod, and when you are starting to get the coordination right then move to welding alu..
remember to clean the alu before you weld otherwise it'll be really really hard to get any good looking welds ^_^
Good luck, I am looking forward to hearing about your progress

I have had a miller 180sd for 3 years now. Used the piss out of it, works great.

Even welded up to 1/2" thick aluminum once, although preheating is a must.

I wouldn't have an issue doing 1/4", now if you said you needed 10ft of weld done at one shot, the air torch aint going to cut it. You would want to stop and let it cool. I have had the torch hot enough even gloves didn't help much. :)

You will need 70 amp breaker for the 180sd though, or be very careful in your max setting.

Aluminum is the worst to weld in terms of power requirements, so just be aware of that.

http://www.millerwelds.com/education/success_stories/story71.php

Draws 16 amps 230 at full tilt? Cool. (third to the last paragraph).

I didn't see it having slope up/down control. Then you should have remote control Foot pedal. Or do as I did and make a control knob mounted on the handpiece. It's just a potentiometer.
If you don't slope down, there will be a crater at the end of the weld.

I have a miller 180, and I do a lot of AL with it. If the work you are welding is big *and* 1/2 thick, you will need 250+ to get it all hot enough. If it's not as massive, say a couple of smaller 1/2" parts welded together, then my 180 can do it. It involves flooring the peddle at max amps. The basic issue is AL conducts heat very well, and the mass of the part sucks the heat away from the joint.
-Les

I got the contractor kit Miller offers with an air cooled torch, regulator, flow control, some consumables, and a foot pedal. I think a stick holder is in there too.

Lesd

Thanks for the info, I was wondering why aluminum would take so much to weld.

Alum is a very good conductor of heat, it just soaks it up like a big magnet to steel.
Anything that is a good electrical conductor will conduct heat, just take a short lenght of wire about 4 to 6 inches long and put the one end in a flame and see how quick the heat runs up the wire to the point that you can not hold it. The better the conductor the quicker the heat moves. Hence the suggestion to preheat
Jeffy

Okay, my brother just bought a Miller Synchrowave 180 SD which according to the local Community College Shop teacher is the best minimum effort system. So, you'll need a healthy 220 volt source with a minimum of 50 Amp breakers to go beyond 135 amps on the ouput. The 135 amps was what we were using for welding some crows foot aluminum plate (about 1/8 inch thick) and getting good penetration....hmmmmm....

I blew a 50 amp and 60 amp breaker both with ease on mine.

I would go for the 70 which I have yet to blow.

The thing about aluminum on top of the tendancy to transfer heat, is you are using AC, so already you are down by 1/2 the power.

I have a 100A 230 breaker going to my 20 HP 3 phase convertor. I should run in 3ph from that eh?
I could probably rig something up, like two lines coming from the breaker, just run one at a time. I would not be running the CNC at the same time anyway.

@Nervis: From the blurb at the website you pointed to, it seems your machine will adapt to the voltage and take 1ph or 3ph. So it should just be able to connect directly to your 100A 230V. No need to suffer the losses through the 3ph converter.

Disclaimer: I only go by the info on the webpage, so you better check it can be connected to 230V, 100A, 1Ph to be sure. You will be running 100A through just 2 rectifier legs instead of all 3, it may not be rated for this.

And 100A 230V would probably be an overload for your converter. Does'nt matter for your welding machine though, as the load will not be continous.

So, just a cautionary note: Make sure that the wiring will handle the current of whatever breaker you have.....hot wires can cause fires.....

Also....a quick acting breaker will have to be rated higher then a time delay breaker...you know fast blow versus slow blow.

You can weld any thickness you like with just about any welder. The catch is you have to do it in multiple passes. When one talks about "how thick can you weld with this welder" we are generally talking about how thick you can weld in one pass. You can weld very thick material by beveling the edges of joint and then making multiple passes over the weld. By beveling the edges and then filling the bevel with filler rod, you build back the metal and your multiple passes provides the "penetration". Granted this is time consuming, but it works for any thickness of metal. You also have to take the duty cycle into account so you may have to start and stop the welding bead depending on how long a weld you need to make. If you're using an air cooled torch, it's gonna get hot doing aluminum, so you'll be limited by how much pain you can take :) .

I am about ready to purchase a TIG unit for my home shop as well. You will pretty much need 230v to get you any sort of power to do things in a single pass. I have pretty much decided on a Thermal Arc 185 as this seems to have the most bang for the buck, is light and protable, uses inverter technology so uses much less current and will make it much easier to run a dedicated circuit in the garage since is uses less current. I'd really like a Miller Dynasty 200DX, but it's just out of my price range.

Jay

Thanks for the info.

I got a chance to talk to a welder over the weekend, he pretty much said the same thing, I'll probably want a water cooled torch. I think I'll learn a bit with what I ordered, and maybe in a month or so start looking at water cooling units and torches.

For me, I'm going to start with an air cooled unit. I'm not doing any production type stuff and I don't really have a way to preheat the aluminum ( I wish I did cause I get cracking of the welds as it cools too rapidly) to prevent the heat from absorbing quickly into the metal. I'd like to get a water cooled unit, but funds prohibit that at the moment. It's certainly something I'll consider doing at a later date.

Jay

"Thermal Arc" machines ( by Thermadyne) are a good unit that will do what you want. Their small welders will run off 110V or 220/240V single phase.
There are several models with different upper end amperage levels (price goes up with capability). I have one that will produce 150 amps weld current. I think the next model up is a 180 amp unit.
That would produce a hot enough arc to weld 1/4" alum. in the AC mode (you will want to buy the High frequency option for AC welding)
If you choose to weld alum. in the DC mode you do not need nearly as much current BUT your alum. must be very clean and the weld bead is difficult to see joining. You get much deeper penetration of the weld pool with DC which makes welding thin pieces(<1/8) difficult as well.
Water cooling is nice but not necessarily required if you are not doing long duration (timewise) welds.

The Dynasty 200 seems to run fine on a 30 amp circut even at 200 amp output.

I'd attach a pic but the "manage attachments" button doesn't seem to want to cooperate right now.

My welding skills stink.

I have a question for yoy TIG guys. I'm just running beads across aluminum plate at this point, practice. My welds seem to get fatter and fatter as I go. Is that just me adding too much filler as I go, or moving too fast or slow?

The Dynasty 200 seems to run fine on a 30 amp circut even at 200 amp output.

I'd attach a pic but the "manage attachments" button doesn't seem to want to cooperate right now.

My welding skills stink.

I have a question for yoy TIG guys. I'm just running beads across aluminum plate at this point, practice. My welds seem to get fatter and fatter as I go. Is that just me adding too much filler as I go, or moving too fast or slow?

Back off you juice or speed up. Notice that it takes longer to start a bead too. Same deal in reverse.

So you don't stay at a constant speed? You speed up as you go or back off on the pedal? Damn, that's a whole new deal isn't it. This is going to take some practice.

So if I start at 150A, how much do I back off in general as I go, like 25%?


How do you prevent that little crater at the end of the bead?

Maybe more then 25 % Your Dynasty is a little different them most because of all the adjustments. Try to get to a point where you can weld as fast as you can. It will keep the aluminum from getting too hot. Then it will be easier to stop the crater and the end of the weld bead. Try to back off the pedal some while adding filler will get rid of it. If it's too hot it's a bi*ch. The faster you go the less distortion you will have and the more the uniform weld bead. Try your pulse after you get more practice in and it could help you some. about .9 pulses per second to start.

Learning how much to back down on your foot-pedal will come with practice. A good way to help judge how much and to become more consistant is to scribe 2 well defined lines about the width of the bead you wish to maintain. Run your bead between them so the edges of the weld pool/bead just cover the lines. Just a little experience working the pedal, your travel speed and torch manipulation will help you lay down a consistant width bead. I find it is generally easier to back off on the pedal than to speed up. You will also maintain a more uniform bead crown and laps this way.

The work is heating up all over, making the bead spread out more. You can go faster to aviod that.

sounds like to much heat

Thought I'd post this up for the "real" TIG welders so you can have a laugh :D .

These are my first four welds...well those first couple are more like explosions, the last one may qualify as a bad weld.

Whatever, I'm getting better slowly, just did some butt welds today that did not look half bad.

I still crack up when I see that first one....WHOA, this doesn't look right LOL...smoke all over...LOL

Just remember that aluminum is quite forgiving---> you can rework the weld until it is pretty, and mechanically sound with the torch. Until you get used to the torch just try some welds without filler rod.

OK guys I thought I would put in my 2 bits. I own a miller syncrowave 350LX. What do I love about this machine, it is quiet. The cooling fan only comes on when needed, and that depends on how high of amerage you are using. Even at 300 amps it doesn't come on too often. I also love the square wave adjustment, what did we do before square wave????? I do a fair amount of welding on 1/4" aluminum tubing. I have a Weldcraft Wp20 water cooled torch which I love because it is small and easy to manipulate in any position. This torch is rated at 250 amps, but I push it over 300 all the time with excelent results. My best results with heavy aluminum is to use DC straight current(electrode negative) and pure helium gas. No preheating is necessary, even on 1/2 inch or thicker workpiece. When using this system make sure your alum. is clean by wire brushing as you won't have the benefit of the high frequency cleaning. The weld will have a dark soot on each edge with a shiny strip down the middle of the bead. The soot will wire brush off easily, as it is powdery. You must push your filler rod in with authority or it will burn back on you before you get to the puddle. Helium ionizes 2x hotter than argon. You can use an argon/helium mix with AC current for a boost in thickness welding. But if you want to move fast and get good penetration use straight helium. It also cuts down on the current. I have a 125 amp single phase breaker and have tripped that from time to time so I open the panel and put a blower on it to keep it cool and it never tripps. I also have a cnc machining center in my garage. I welded aluminum one day while running the machining center and my g54 offset kept moving on me. So I don't run the machine while welding anymore.

Holy smoke, that is one pretty weld.

Mortek, that's illegal and obscene. Go away. (flame2) Seriously, I can't do welds with that uniformity and bead shape even with the most benign mild steels. I am bitter with jealousy!

Nervis, you're doing better than me. I gave up on aluminum, I just can't seem to get the hang of it, although my steel welding is getting much better. I'm using a Lincoln SQ175, which is pretty much a hobby/home machine, but it's pretty good for what I am attempting.

I applaud your effort.

I have many years of tig experience, mixing argon and helium vs. straight helium has it's benefits, ie; less amps used. I found using straight helium made for harder starts of the arc. Great results are noticed with a 75%Ar/ 25% He. I have a bottle of both and plumbed them after the flowmeters to achieve these mixes, took a while to nail it and it's cost effective, mixed gasses are a bit pricey. The machine I use is an L-Tec 250 HF Plus bought new in '92 and still produces great welds. I bought it because Linde developed tig and I tend to stick with products by company's who develope them.

B_Bueno,
I agree with you about welding with straigh helium when using ac current. Helium will cause an eratic unstable arc, and cause harder starts. I am talking about using helium only with dc straight current. I mixed my gasses just like you do until I bought the miller 350lx. With square wave technology I find that I don't need to mix gasses much any more. If you haven't tried using dc straight on thick aluminum you should try it. It takes some getting used to, but if you are welding on 1/4 inch thick or thicker I would highly reccomend it.

Never used dc on al. Will definetly give it a go. What should I be aware of for the "getting used to it" part? Thanks

We use a synchrowave 250dx not portable but extremely reliable and welds GREAT!!!! Controls are easy to use as well. If you get one get the tig runner package