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Thread: Using your portable mig as a simple wire feeder w/gas powered welder - 100% dty cyl

  1. #1
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    Default Using your portable mig as a simple wire feeder w/gas powered welder - 100% dty cyl

    I have a Northern Industrial Mig/Stick 200 in my service truck, and a late 90's Miller Bobcat 250.

    For the most part I do stick welding at work (Field service tech for a concrete paving company), but there are more times than I care to think about that I have to weld in confined areas where you can't get a stick in the hole, get the angle and movement that you need, or flat lack of skills stick welding metal less than 1/8" without burning through (my welder is bitchy and does not like to stick weld at low amps with the 3/32 rods).

    Since I am in the field, gas welding is out, it always seems to be windy when I choose to weld, so flux core for me.

    I take the NI MIG ground clamp, connect it to the stick torch port and clamp that to my Miller torch. The Miller ground to the work, and get a guesstimate setting on the welder (welding selector ~ Low wire/Hi wire and dial the amperage in) and go at it. 35 feet from my truck and all I have control over is the wire speed, but I have a good feel for the settings now after a little practice.

    Kind of a drag running 3 cables, but the end result is worth it. No more hitting the duty cycle with only another minute of welding to go.

    Double bonus, I can now MIG up to 3/4" thick now rather than the 5/16" it's rated for at a pale 30% duty cycle.

    I've done a couple of fabrication projects off my bumper and I am real pleased with the results.

    On a whim, using Lincoln .035 wire, and the Miller maxed out, my wire feed can not feed fast enough. Really wide spray pattern, but good penetration. I'll try to post some pics of some sample welds this weekend.

    FWIW - Everlast and other import companies really need to get on board with suitcase MIG welders for these applications. I still can't grasp why the name brand suitcase units are $1700 plus. If you are running an older gas welder, you still don't have control over the amperage, only wire speed.

  2. #2
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    You've built a jumbo spoolgun for your bobcat. Nice to have a CV power supply for things like that.
    Long arc, short arc, heliarc and in-the-dark!

  3. #3

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    If it works for you great, but you probably aren't getting the results you think you are within the weld. You are going from a process that was meant to be Constant Voltage to a "make work" constant current wire feed. A voltage sensing suitcase like a Miller or a Lincoln requires a third wire to clamp on to sense the voltage to properly feed the wire. If you are welding up 3/4" in single pass, then you will likely burn your gun up quickly because it has a limited duty cycle as well and you are ignoring that but more than that, the weld won't be strong as a multipass weld. Your wire feed mechanism likely isn't intended for a hundred percent feed time either and will burn up because it is assumed that the normal weld circuit overheat would protect it.

    For our welders and the "suit case" industry, it really doesn't make sense because it's easy enough to run an extension cord for our welders that is heavy enough to run the unit properly any where a cable can go. We can offer that kind of unit as one of our factories produce it, but it doesn't make good marketing sense since the industry is headed toward inverters and a simple plug. That's sort of like us considering producing High Freq boxes for engine drive welders...not a lot of point and it isn't our market.

  4. #4
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    I believe the Miller Bobcat is a CC/CV power supply.
    Long arc, short arc, heliarc and in-the-dark!

  5. #5
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    Quote Originally Posted by Rambozo View Post
    You've built a jumbo spoolgun for your bobcat. Nice to have a CV power supply for things like that.
    It's big for a simple wire feeder, but still half the size of a suitcase unit. Not sure I would call it a spool gun.

    Quote Originally Posted by Rambozo View Post
    I believe the Miller Bobcat is a CC/CV power supply.
    It is. Most of the gas/engine driven welders in the field have that option. Since mine is an older model, I don't have the connection port for a suitcase to control anything remotely. All settings would have to be done at the welder. The newer models do have the ports for a remote control for TIG and MIG.





    Rotary switch 5 to Low or High Wire, Rotary switch 4 to Negative for the flux core, fine control (6) to wherever I need it.

    Quote Originally Posted by performance View Post
    If it works for you great, but you probably aren't getting the results you think you are within the weld. You are going from a process that was meant to be Constant Voltage to a "make work" constant current wire feed. A voltage sensing suitcase like a Miller or a Lincoln requires a third wire to clamp on to sense the voltage to properly feed the wire. If you are welding up 3/4" in single pass, then you will likely burn your gun up quickly because it has a limited duty cycle as well and you are ignoring that but more than that, the weld won't be strong as a multipass weld. Your wire feed mechanism likely isn't intended for a hundred percent feed time either and will burn up because it is assumed that the normal weld circuit overheat would protect it.

    For our welders and the "suit case" industry, it really doesn't make sense because it's easy enough to run an extension cord for our welders that is heavy enough to run the unit properly any where a cable can go. We can offer that kind of unit as one of our factories produce it, but it doesn't make good marketing sense since the industry is headed toward inverters and a simple plug. That's sort of like us considering producing High Freq boxes for engine drive welders...not a lot of point and it isn't our market.
    Yes, I may be running the torch past it's built in duty cycle at 200A for extended periods. I have done some extended welding in the 180+ range with it and the torch cable and internal 6ga cable did not get past warm to the touch. The NI welder is doing nothing but feeding the wire on it's own power source, and transferring the Miller power through the married port from stick to the MIG. The NI inverter is doing nothing and also set to minimum as a precaution. I don't design these things, but I would think that the wire feed would have a much higher duty cycle. It's run time and load from the tension on the spool. I get it that it is just an itty bitty AC motor driving the feed.

    I am not by any means a professional welder. I am an equipment first responder medic, so my welds don't have to be mission critical and pass inspection, they just have to hold. Most of my welding is 1/2" or less material. If I am doing the thicker stuff, I go with stick, because odds are good there's room to work. Like everything, I like to see just how far it can go.

    If you look at the suitcases that are out there for Miller and Lincoln welders, they are wired the same way I am doing mine. The newer models have the remote control cables and ports to control amperage on the CV settings, plus a sensing circuit on the suitcase so you are not running a constant hot torch (like I have to with my setup). They are just using a high amperage contactor/relay to open the torch circuit through the suitcase.

    ETA - For shop use the portable mig units are fine as they are built self contained, but working in the field, you sometimes need the duty cycle of a large shop MIG that the portable units can't handle, and it's not practical to load up a 300A & 400# shop unit that has the 100% duty cycle at the high amperage for the 1/2"+ material welding.
    Last edited by sticks; 02-24-2013 at 01:05 PM.
    Sticks
    Field Service Tech for a Concrete Paving Company
    Location: The corner of "No" and "Where"

    "If they break it, we will fix it"

    AKA

    "Find some scrap and build a new one"

  6. Default

    Quote Originally Posted by performance View Post
    If it works for you great, but you probably aren't getting the results you think you are within the weld. You are going from a process that was meant to be Constant Voltage to a "make work" constant current wire feed. A voltage sensing suitcase like a Miller or a Lincoln requires a third wire to clamp on to sense the voltage to properly feed the wire. If you are welding up 3/4" in single pass, then you will likely burn your gun up quickly because it has a limited duty cycle as well and you are ignoring that but more than that, the weld won't be strong as a multipass weld. Your wire feed mechanism likely isn't intended for a hundred percent feed time either and will burn up because it is assumed that the normal weld circuit overheat would protect it.

    For our welders and the "suit case" industry, it really doesn't make sense because it's easy enough to run an extension cord for our welders that is heavy enough to run the unit properly any where a cable can go. We can offer that kind of unit as one of our factories produce it, but it doesn't make good marketing sense since the industry is headed toward inverters and a simple plug. That's sort of like us considering producing High Freq boxes for engine drive welders...not a lot of point and it isn't our market.
    The problem with the mig inverters using them the way the suitcase wire feeders are used is that they are in too flimsy of a case and need at least 250 amp capacity and would need at least an 80% duty cycle at high amps. Now if you put one in a case that is the quality of a pelican plastic case and gave it some balls it would take over the flux core portable mig market by storm. I am looking for just such an machine now. I am contemplating a suitcase wirefeeder because no one has what I have described. If one of the blue or red makers came out with it it would be 5K pluse where a suitcase feeder is 1800 new. I will probably buy used from a rent all outfit if I can not find anything better. The other problem is 100 - 200 feet of run. What kind of power cable would be needed to run that. But for me personally 50 ft of cable would be enough. I think there a still some obsticals to the inverters taking over that segment of the market.
    Last edited by TheGary; 11-04-2013 at 12:30 PM.

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