[Ian Pratt]

I've been watching Jody's videos on scratch-start TIG welding using stick welders as a power source. I own a Miller Maxstar 150S that I hope to use with a TIG torch setup.

I understand that welding TIG on 115v 20A circuit is not ideal, but unfortunately I am in a situation that is not under my control and cannot install 230V power. I need a solution that creates the least fumes to comply with good housekeeping practice; I would buy a MIG welder, but I cannot afford a new machine in a addition to a tank&gas, a flowmeter/regulator. Buying a TIG torch with a valve and separate power/gas connections plus a fitting and perhaps an extra hose and some consumables seems to me to be a quarter of the cost over buying even a low end inverter MIG machine.

I've made inquiries at a couple of the major online welding accessory supply stores and received strange feedback. One site stated that my Maxstar150S has a port in the rear that accepts Argon (I took that to mean that a single-wire torch that plugs into the Maxstar's Dinse connection would work rather than having to adapt the gas/power another way). But Miller's user manual is confusing (Three models are conflated in one manual, but I'm also finding out that each has its own peculiar presets) and I believe my welder was setup for stick welding only and has no internal gas delivery.

Which leads me to my next feedback, which was "Miller advises that the Maxstar 150S cannot be used as a tig welder. The arc voltage for tig welding is generally around 10 to 15 volts. Since the Maxstar 150S is designed to stick weld only it has an arc voltage of 20 volts. If you try to tig weld with it the unit will sense the lower arc voltage and will shut down because it believes that there is an arc voltage problem." Although this is pretty nonspecific and is probably right, and also considering I've read similar posts from others here, I am nonetheless still confused.

If a torch manufacturer specifies that a 150A rated torch used at 70-130VDC with a thoriated 1/16 tungsten (plus shielding gas and cup/gas lens) and the power source (Maxstar 150S) is rated 17.6 amps current draw on 115v AC power when set to 70VDC, will someone please explain to me why a voltage drop occurs when attempting to weld using DCEN (Again, my interpretation)? Obviously I haven't attempted anything because I don't own a TIG torch yet

[MinnesotaDave]

The information is correct.

On a whim I tried to tig with my maxstar 150s, it would light right up, half second later or so, shut off the arc.

Which is pretty annoying considering cheap inverter stick welders do scratch start tig just fine.

The harbor freight one does, and so does the century 90 amp stick welder - tested that one myself and it tig welded very nice.

[weldin mike 27]

I never thought about that until the other day. I thought you could stick with any tig, and tig with any DC stick. Live and learn.

[dsmabe]

Id say you can tig with any stick and stick with any tig, as long as it is a transformer bared machine, or the insurer based circuitry allows it. As for the op, check Craigslist, if you can't find anything and just want to get some arc time. Get the most expensive/highest quality tig machine you can afford. Even if it ends up being a harbor freight machine. Just do your research, you might find a welder that is just outside of your budget, but something you could save an extra week for and get a much higher quality machine. Me personally, i like everlast right now. Even though I had a terrible experience with customer service, their machine so far is great. For $275 you can get their 140 amp, dual voltage stick/tig welder.

[MinnesotaDave]

I never thought about that until the other day. I thought you could stick with any tig, and tig with any DC stick. Live and learn.

I chalk it up to Engineering meets with Marketing and decide that the programming should eliminate scratch tig so people buy the more expensive version of the welder.

My opinion is they figured an experienced welder would just clip a tig rig to the end of the stinger and scratch up.

By eliminating that ability, they force a guy to buy the Lift-tig or High-Freq model.

If a cheap harbor freight or century model will scratch tig, then the Miller had to have been purposely programmed to prevent it.

Edited, I took out language that made it look like I directed comments at weldin mike 27.
When really I was directing them at the black helicopter, suit wearing, Feds that forced Miller to do this to my machine.
Sorry mike

[weldin mike 27]

I had never even considered the point.

[weldin mike 27]

Not at all mate. Its not a thought that crossed my mind. It is only 110v that this happens on? Because we don't have it in AUS.

[Braehill]

I actually had an earlier post talking about using a HF 80 amp lunchbox to tig with. It welds beautifully for a very short distance, then seams to pick up the wrong voltage and goes to some weird half power mode. I can usually long arc it and fool it into welding again. I use it for welding angle iron and the like in places that would be terrible to get any other weld source into. It's not ideal, but it works. It's a shame because it welds really nice when it welds.

I'm sure the stick only version of the Maxstar has similar circuitry that picks up this voltage discrepancy also.

I know that there are some Maxstars that will work for scratch start tig, because our Boiler repair guys bring one every time they come to plug a leaking tube. I even used theirs one day to make a quick weld on a bracket was in need of repair near where they were welding, a beautiful welder to weld with no doubt.

Len

[MinnesotaDave]

I actually had an earlier post talking about using a HF 80 amp lunchbox to tig with. It welds beautifully for a very short distance, then seams to pick up the wrong voltage and goes to some weird half power mode. I can usually long arc it and fool it into welding again. I use it for welding angle iron and the like in places that would be terrible to get any other weld source into. It's not ideal, but it works. It's a shame because it welds really nice when it welds.

I'm sure the stick only version of the Maxstar has similar circuitry that picks up this voltage discrepancy also.

I know that there are some Maxstars that will work for scratch start tig, because our Boiler repair guys bring one every time they come to plug a leaking tube. I even used theirs one day to make a quick weld on a bracket was in need of repair near where they were welding, a beautiful welder to weld with no doubt.

Len

Yeah, the maxstar comes in three models - the base model 150s is the one that doesn't tig (the one I have).
The other two, one is lift-arc 150STL, the other has high freq start 150STH.

I have not tried to fool it into keeping the arc going - maybe should try it again.

[Ian Pratt]

Thank you for all the replies. It seems I'll just have to go forth and give it a shot, and in the worst case I'm heading to Harbor Freight.

I'm still confused about the difference in voltages when stick welding DCEP and TIG DCEN. If I isolate the work from the table, will this help with volatge drop? Also, I've been reading up on shielding gas and it seems that adding Helium to a mix increases heat and therefore more power is needed- therefore making the DCEN profile closer to DCEP? In CK Worldwide's TIG parameters guide, it does recommend a 75Ar/25He mix for general purposes. I will be welding 1" square .120" wall tubing.

[Oscar]

can't transform DCEN into DCEP. Either the electrons are flowing into the tungsten or out of it into the work piece. For 120-wall you should be fine with having 150A on tap. Helium does increase arc intensity for a given amperage, so the Ar/He mix will give you "bang for your buck", at the expense of the added expense of buying a helium mix.

[Ian Pratt]

To be clear, I am not trying to transform EN to EP- but I am trying to compare the voltage at the weld versus what the machine does in either case. It seems Miller has a feature that reads a lower voltage at the weld when using TIG DCEN and shuts off.

[weldin mike 27]

You've got the machine, it doesn't work for you right now, you have theorized that adding helium may help. All you can do is give it a go and see if it works. (As in allows more arc voltage) If it does great. If not, move to other options. I don't if anyone can tell you how much extra volts the machine needs or how much extra helium will afford you. Good luck.

Glad to be around people who can see welding as a passion.

[MinnesotaDave]

Thank you for all the replies. It seems I'll just have to go forth and give it a shot, and in the worst case I'm heading to Harbor Freight.

I'm still confused about the difference in voltages when stick welding DCEP and TIG DCEN. If I isolate the work from the table, will this help with volatge drop? Also, I've been reading up on shielding gas and it seems that adding Helium to a mix increases heat and therefore more power is needed- therefore making the DCEN profile closer to DCEP? In CK Worldwide's TIG parameters guide, it does recommend a 75Ar/25He mix for general purposes. I will be welding 1" square .120" wall tubing.

I think you've missed the overall point - it's not the DCEP or DCEN polarity change that is causing the reduced welding voltage.

It's the difference between stick welding and tig welding. Tig has a lower arc voltage than stick in general.

That machine will stick weld in either polarity.

This chart shows the welding voltages for tig and stick for the Maxstar 150sth

Tig, 14-16vdc
Stick 22.8-26vdc

image.jpg (44.67 KiB) Viewed 895 times

[dsmabe]

Just thought of a question, why the lower voltage for tig? The reason I ask is I use a Old Lincarc 250 at work and my go to voltage for most scratch start tig work is 50volts, I can't remember right off but I don't think it even goes down under 30volts.

[Braehill]

I think these inverter go into the shut down mode because of a feature that's built in for when a rod sticks and it picks up a short circuit. I know the one I have powers down while stick welding if the rod sticks.

Len