ALT-304 on sheetmetal

[dseman]

Hawk,
Speaking of the ALT,.....what is the smallest steel gauge that you have been able to comfortably weld with it in short-arc? If you were to compare it to the MM251's capability on sheetmetal, would the ALT be better still? I'm sure the ALT is great for the thicker stock, but my experience (with transformer migs) shows that having a larger machine slope on the lower end really helps with the sheetmetal gauges. However, on the CV inverters, I'm not sure that slope is really that important anymore since the inverter's arc responds so quickly. I'd be interested in any of your experiences.

I guess what I'm trying to understand is what makes a great short-arc for an inverter based CV machine. For a transformer CV, a higher slope provided a lower short-circuit current--which is what is needed for smaller wires. I'm guessing approx. 230amps short circuit current for a 0.023 dia. wire. The next most important control would be inductance, which allowed you to slow the rate of current increase to the maximum set by the short circuit current. When I look at the relatively flat voltage curves of the inverter, I'm not sure how the short circuit current is limited for the finer wires used for sheetmetal. I know the inverters have the arc control which I think mimics the inductance control of the transformer machines. Any idea of how the short-circuit current is limited if the volt/amp curves are relatively flat? Or is the 'arc control' really adjusting the slope of the machine instead of the 'rate of increase' like a change in inductance would provide?
thanks,
-dseman

[HAWK]

dseman,

I am using .035" wire and can do 16 guage easily and 18 guage takes some finesse. I'll be glad to pick up 10 lbs of .023" and order some drive rollers and let you know what I can do with it. I will take about 4-5 days to get the rollers for my 12RC. That is the only feeder I have right now because I kept it when I sold my mobile rig.

I usually turn on the Dynasty for anything I can't get with .035, but will be more than happy to check it out for you. Do you have time to wait for me to get the rollers?

I agree with you that "arc control" may be adjusting slope. It used to be called an inductance control. However, it makes me wonder about a couple of things: (1) Why has Miller discontinued the variable and tapped slope machines? This year the CP 252TS was dropped. Sad! Perhaps they think the newer inverter multi-process machines can take their place. (2) Why has Miller changed the name from "inductance" to "arc control"? My older XMT was labled "inductance" and my ALT shows "Arc Control". Whatever the "Arc Control" does it will make the puddle go from a drippy wet to so dry it will just hump up on the sheet metal.

I know the new lower end PC board in the ALT has made the lower end of the VA curve meet around 10 volts and 25 amps. Andy told me the actual current is between 20 and 25 amps. Maybe Miller has engineered the new machines to adjust slope by changing the PC board. That may be why the knob now says "Arc Control".

I must agree with your logic. Maybe Andy can shed some more light on the picture. As for the MM251 and the ALT 304-I can't tell you until I get my feeder on .023" wire. I really think by the machine performance on .035" that it will be very similar. I do not think the bead appearance will be the same. The inverter beads are slicker and cleaner than the SCR output machines. That's a personal opinion and will probably start a war...

[dseman]

Hawk,
Again, thanks for your unvarnished reply. I'm a bit taken aback by your offer on the 0.023, and the level of concern you've shown. I really don't want anyone going out of there way to personally spend money on the question, I just thought that maybe you had run some 0.023 and could compare it to a transformer mig. I've used the mm251 and others on the fine wire and they run quite well. I've not yet had the experience of running an inverter mig, so I thought I'd defer to you or Andy since you guys seem to have run all of the machines at one time or another. I have run the dynasty 200/300s and they are quite nice.

Maybe if the question hangs around a bit more Andy can reply with any observations he may have.

I still would like to know more about the arc control, because as you said, it has changed names, and I doubt if inductance control and a stable low voltage are sufficient enough to produce a quality arc down on the low end.

thanks again for your reply and offer,
-dseman

[HAWK]

dseman,

I may pick up some .023 anyway just for kicks. I would like to satisfy my curiosity bone also. Here is something I can tell you. I ran .023 on my XMT 304 with the VA curve producing 50 amps at 10 volts and it did okay on .063" x 2"x2" tube. I had forgotten about that. I think we will both be pleasantly surprised. I will let you know. I don't know if this has anything to do with the lower end performance, but the SCR output of the MM251 produces the brushed bead where the ALT produces a very smooth bead.

Don't worry about the wire and rollers. They are not much.

[dseman]

What a guy!
Well I would be interested in the performance of the 0.023 and I think some others would as well. As far as being able to weld the 0.063 tube with the XMT-304, that's still pretty good considering the 50amp minimum. I've got to believe that if we connected an oscilloscope to the mm251 and the ALT that the inverter would have a much smoother output.

Thanks again for running the test, I'll be looking forward to the results! I wonder if the mm350 has any programs to assist it's short-arc performance, like the red guys have in theirs.

-dseman

[HAWK]

dseman,

My Techtronics OS bit the dust. The display was more than a comparable unit. If I have the chance, I'll hook up a scope and post a freeze frame. Don't hold your breath unless my dad is willing to run his scope by the shop.

[HAWK]

dseman,

I was fortunate that my dealer had .023" drive rolls in stock. I put them in and stuck a 25' Pro-Fax gun on my 12RC. 15 volts at 205 IPM gave a killer short arc on 20 guage sheet with a minor amount of backside penetration. I was able to dial down to 14.3 volts and 193IPM and maintain a good arc. All this was run at 40% inductance. At 65% inductance the beads wetted out considerably , but still no burn through. The arc was very crisp and uninterrupted. I am well pleased with the .023' wire and feel good that 24 guage won't be a problem. I did not have any 22 or 24 guage on hand. Maybe I can pick some up tomorrow. I think I'll return this 25' Pro-Fax gun. I am really fond of the Bernard guns and like the 12 footers. The bottom line here is the ALT rocks on 20 guage and .023" wire with 14-15 volts and 193-205 IPM wire speed. I'll post again when I get the 24 guage sheet and a 12' bernard gun set up for .023" wire. That will take a few days. No dealer in town stocks a good selection of Bernard! That's the best I can do for a few days until the rest of the goodies come in.

What do you think? Are you surprised?

[dseman]

HAWK,
Yes, that is a very nice suprise. It bothered me a bit that even thought the ALT was advertised for smaller gauge stock, that no one was really using it for that. When I viewed Andy's site for the machines used in the motorsports industry, it seemed that they always used an scr-based mig for their bodywork and light gauge welding. It really does seem to be very versatile from the low end to the high. If light gauge were the only work, then I would say there are less expensive machines to use, but if you wanted one machine to do it all for your steel work, then I think the ALT may be it. Thanks for taking the time to make the test...I really do appreciate your effort in time and money.

thanks again,
-dseman

[HAWK]

dseman,

You are welcome. I'll let you know more when my new Bernard gun and some 24 ga sheet gets in later in the week. Also if it helps your decision : Rousch is tack welding 24ga with the ALT. In my honest opinion it smokes the current XMT in the 304 and 350! I'll post more as soon as the equipment comes in.

If you ever need info on anything I can access, just let me know. I'll be more than glad to help you any way I can. I also have some info on the inductance and how the inverter controls the lower end of the VA spectrum. Please email me at [email protected] and I'll turn on to some cool stuff. It gets rather technical and I don't think most forum members will want to delve into it that deeply.

[ASKANDY]

dseman,

All good questions!!
Been at the coast visiting my wifes parents. I do have some Alt304s at Roush and DEI doing light gauge material. Roush uses it for spot welding bodies together (24GA) and on booms in the chassis shop for doing frames. Most of the race teams are using the smaller MIGs because of their layout and the all-in-one MIGs are easier to pull around and offer good performance for all levels of experience. The teams that spend the extra $$ to put in boom welders go with the better power sources. The Inductance control was renamed to ARC control because not many people knew what inductance was but they understood that changing that knob changed the arc characteristic. It works as inductance in MIG and dig or arc force when stick welding.
For a continuous beed welding 24GA and under, the Alt still needs some operator finess. The MM350 is killer on light material (even with 30/35 wire!)and so is a new machine we have coming out later this year but will not have the high end that the MM350 has and it won't have pulse.
If you are bent on an ALT, get them soon as they have been replaced by the XMT350.
The XMT350 also has a low V/A curve minimum at around 25 but the unit was designed for heavier welding and I'm sure the arc was tuned that way. I have no arc time on the new XMT350 so I can't give you an honest opinion. I doubt it is as good as the ALT304 and I know it won't be as good as the MM350 on thin gauge.

Hope this helps.

Andy