suitcase wire feeders and dual shield ?

Anybody have any comments on these voltage sensing wire feeders.I see lots of used Lincoln LN25's on the used market but I am looking at a
used Miller 8VS with a 180 amp torch.I am hoping to run .035 and.045 dual shield mild steel and SS connected to Pow Con 400SM and weld up to 1/2 inch plate. This seems like a newer model for Miller and wanted to check if this was one of their lemon models or if it actually works as good as Lincolns.It is a lot smaller and lighter and only takes 8 inch spools and the torch might not be heavy enough but I am not sure how much amps I will need. I have been using a Lincoln 170 with .035 dual ss and it works but right on the edge of capacity.Hopefully with more power it will be closer to spray mode? Any comments are welcome. Thanks Jim
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snipped-for-privacy@sbcglobal.net (Jim Moser) writes:

From experience about 10yrs ago with 1.2mm (about .050inch) rutile FCW MIG using Ar/20%CO2 shielding gas, was in full spray mode at 240A (and 24V). Was reckoned:
<180A - dip transf.
180A-210A - globular
>210A - spray
Downhanded at 240A. Positional at 200A. Both smooth, but 240A could see point at which wire melted and the flow of metal pinched-down to shoot across to the workpiece.
Basic FCW existed but could not be used positional, as flux thin as water and metal fell away in gravity - so downhand only (well, a skilled weldor could do something, but not capable and easy like rutile FCW)
Anyone correct on any points?
Richard Smith
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(Jim Moser) writes:

Thanks Richard for the response, Sounds like the 180 amp torch is marginal for spray but I don't know if I really need to spray with dual shield or just more voltage will flatten it out. I am not looking for a process that takes a skilled welder, that is the beauty of the dual shield SS I have ,it is user friendly.I couldn't respond for awhile on this board after reading about Ernie's accident, I just felt heartsick He is one of the jewells of the web, even though I don't post here often, I browze occasionally and am always amazed at his committment to helping anybody. Thanks Jim
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I have used several suitcases years ago. With a constant courrent power source I had great difficulty running .035 wires. The units ran .045 like a champ. It is a nice if you have a suitcase that can be switched from constant current ( stick) to constant voltage ( wire feed) power sources. Many suitcases without the optional internal switch can only run on stick machines. Randy

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Most brands have the option. I ordered a "canox" wirefeeder on a bid invitation through the government agency I was working for. The supplier didn't read the specs and I received the unit without the contant voltage option. They had to eat the cost and upgrade me. We wanted the option in order to have a backup wire feeder for the CV power supplies. About three years ago I was using a suitcase labelled as Thermal Arc. We had it hooked up to a constant voltage supply. The main difference between the two in operation is that on constant current the drive motor is variable speed increasing speed if the arc length increases and decreasing speed if the arc length decreases. On constant voltage mode the drive rolls are running at a constant speed and the power supply controls the voltage ( arc length). I have found difficulty gettting a good weld using CC with small wires such as .035. I suspect the motor cannot respond quickly enough. Randy

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wanted
works
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I did a quick look at a Miller 8RC and 12 RC suitcase units. These are for CV applications only. You're right from what I can see. You have used suitcase units more than I . The ones I was around in a shipyard were CC. running .052 flux core. Suitcase wire feeders can be designed for either power source. It seems that it would be prudent to check out the capabilites of the unit before purchasing. Randy

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Well I did get that Miller 8Vc and it does what I want it to do for now. I was able to get into spray mode with 20 volts and about 160 amps with .035 dual shield 308lt wire. The wire feed seemed strange because you can stop the motor by stubbing the wire with your hand but it feeds perfect while welding. Do these voltage sensing feeders have some kind of electronic sensing to control wire speed even in CV mode? Seems like the motor should have enough torque to bend the wire over in your hand ?? Thanks Jim
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All wire feeders are designed to be adjusted to avoid bird-nesting the wire inside the feeder. It's usually a wingnut on top of a spring, purely mechanical friction control. Too much friction and it will bend the wire into a ball inside the unit.
On 20 Sep 2004 20:25:04 -0700, snipped-for-privacy@sbcglobal.net (Jim Moser) wrote:

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