Welding

Discussion in 'Shop Talk' started by Oxankle, Mar 26, 2005.

  1. Oxankle

    Oxankle Well-Known Member

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    Reading Cabe's post about the steel available to him prompts this; gee I wish I were near enough to haul some of that home.

    Anyway; I have some welding to do out in the pastures, and lacking a portable welder I went shopping. Not wanting to pay $2600 for a decent portable I looked at the little 140 amp Hobart for $1000.

    However, that little welder puts out only 4,000 watts when used as a generator, whereas a generator costing much less can be had that will far surpass this.

    I wound up purchasing a genset that will produce 5,500 watts steady and 8,500 surge. I plan to run my cracker-box welder off it.

    Anyone have any experience or comments concerning this idea?
    Ox
     
  2. fordson major

    fordson major construction and Garden b Supporter

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    one of the biggest farms in our area went this route . mounted the welder and gen on a small trailer that can go behind a truck or tractor to go most any where.
     

  3. Ross

    Ross Moderator Staff Member Supporter

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    Neat idea but I've never tried it. I'm thinking you won't be able to go much over 70 amps. 70 voltsX 70 amps =4900 watts? Still a good heat with the right rod, but kind of limited to 1/8 inch on one pass. I hope you get some experienced answers!
     
  4. swamp_deb

    swamp_deb Well-Known Member

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    You'll need a generator twice the wattage to operate your crackerbox welder. This info is from my Husband not me, I cook and clean, he sells welders and supplies.
     
  5. fordy

    fordy Well-Known Member

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    ..........
    ..............That genset ....WILL NOT ....power your crackerbox welder .
    ..........240 volts x 40 amps(2-20amp breakers) = 9600 watts .
    ..........I would have considered this unit...MGW-2000 AFEU =$2139...50-200 amps DC for welding plus a 4000 watt genset. sold here........
    ............http://www.portable-electric-power-generators.com/
    fordy.. :eek: :)
     
  6. Beeman

    Beeman Well-Known Member

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    There is a 12 volt powered mig welder available that would do what you need. I can't remember the name of it but if you do a search you will find it. I have seen it demonstarted and was very impressed. this would save having a gen. and give you a mig welder too.
     
  7. fordy

    fordy Well-Known Member

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    ...............http://www.premierpowerwelder.com/ this is one of the best on the market I would think ! You can utilize up to a 200 amp alternator for the power unit . Lots of choices, just depends upon how Much you want to spend ...
    fordy.. :eek: :)
     
  8. Oxankle

    Oxankle Well-Known Member

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    Fellows, I may be confused here. Teach me.

    The Lincoln cracker box I have says 225 amps @ 50 Amps 220 input. That is l2,000 watts if you figure 240 instead of 220.

    Now, the plate also says welding current 25 volts, so output at 100 amps is going to be 2500 watts. Everything I need to weld in the field can be done at 70 or 90 amps, so even allowing for winding loss and inefficiency in general 5500 is more than double output, no? Looks to me as if the old copper-wound cracker box could be operated at around l30 amps safely on 5500 watts. The genset is rated at 8,500 surge watts, so startup should not be a problem.

    Am I thinking wrong here? Educate me.
    Ox
     
  9. farminghandyman

    farminghandyman Well-Known Member Supporter

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    we have a hobart wire feed welder that can either use the gass or flux core wire, it is one of the smaller units.

    and we can run it off a 3750 watt generator with ease, and it will weld most things that need to be welded,

    it makes a nice light duty portable unit,
     
  10. fordy

    fordy Well-Known Member

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    ..............Go to HD or Lowes , buy a 25 foot length of #8 direct bury cable with a gnd. , this will have 2-stranded copper runs plus a #8 solid copper run for the gnd. . this cable should be sufficient to carry 50 amp load at 240 volts . Now , purchase the female connector to plug into the 240 plug already on your welder and an appropriate connector to plug into the 240 volt receptacle on your genset , which will probably BE a 30 Amp plug . Now , try and run your welder on your genset ! You'll soon discover just how much juice it takes to run that "crackerbox" ...fordy... :eek: :)
     
  11. herefordman

    herefordman Well-Known Member

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    Ever consider a Zena welder ?, they're sold on Ebay
    Anyone ever tried one ?
     
  12. Oxankle

    Oxankle Well-Known Member

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    I've seen the Zena ads, but you can now buy a small portable welder for about as much as it costs to buy the alternator and Zena welding rig.

    At any rate, I finally got the proper fittings and hooked up a pigtail to my welder today. It pulls it just fine up to 120 amps, and I saw no reason to go further. At 70 amps you can hardly tell the generator is working. Not a significant load at 90 amps but it does change tone a bit as the governor opens. At 120 amps there is little change in engine tone, but when you strike an arc the governor definitely opens.

    At 120 amps the welding circuit is putting out 3000 watts. Friend who is an electrical design man tells me that the transformer core in the welder should be working at over 90% efficiency, so I should be well within the generator capacity.
    Ox
     
  13. fordy

    fordy Well-Known Member

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    ..............Well , I'm glad I was WRong! You'll probably have to do a little testing to determine the "duty" cycle at the highest amperage setting that your genset will support before it kills the engine . My guess is that it will be about 10% or less . I'm going to be in the market for a genset later on this year so I'll be trying the same thing. Good luck , fordy.. :)
     
  14. Oxankle

    Oxankle Well-Known Member

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    Fordy;

    If my friend is correct about the windings in the welder being above 90% efficient then I figure I can get about .90 x 5500 watts out of my welder at max rated capacity, or 4,950 watts.

    If the welding current is 25 volts, then max amperage would be 198, or close to 200 welding amps. I would never push it that hard; as I say, most of what I will weld is light material and 90, certainly not over l45 amps will do.

    The small Hobart portable welder I looked at ran off a generator rated at 4,000 amps and was advertised as having l45 amp max welding current. Using the same 25 volt welding voltage as my cracker box, this figures 3,625 watts at l45 amps, or 90.6% of capacity. If my rig is comparable then the 200 amp figure is close.

    As I understand it, so long as you do not exceed rated wattage the generator duty cycle is l00%. It is rated for 8,500 watts surge, but it would be folly to try to pull more than the rated wattage as a work load. Duty cycle on the welder is a different story; the higher the amperage the shorter the duty cycle. I think at 90 amps it is around 100%, going down to around 20% at 225 amps.

    I think I will try to get hold of someone at Lincoln and see what the pros have to say about this.
    Ox
     
  15. Oxankle

    Oxankle Well-Known Member

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    I looked up the Lincoln site, intending to put the question to them.

    Instead I found a FAQ asking if a fellow could run his 225/125 welder off a gen of 5 or 6 thousand watts.

    Answer; no. You can strike the arc and burn rod, but get poor penetration and poor bead quality.

    Reason; the transformer design is not efficient enough. Burns my buns, but there is no help for that. I'll go back and ask more questions, but the Lincoln people say l5,000 watts min for that welder.

    Now I am faced with finding another, more efficient welder or just buying a welder-gen. I'll start looking. I hate like hell to spend $2,500 on a welder when I need it in the field so seldom.
    Ox
     
  16. fordy

    fordy Well-Known Member

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    .............OX , be aware that BOTH Miller and Hobart make (2) small welders , a 9HP and a 13 HP models . They are DC only , AND Neither of these models have the IDLE down feature which means that you have to set the engine speed at MAX and THEN start welding and the engine will continue to run at max RPM even when you aren't welding . Both Mitsubshi and Honda make engine powered DC welders that have the Auto Idledown feature . Honda's machine is rated at 170 amps DC with a 11 HP motor . Mit's machine is a 13 HP machine rated at 200 amps DC with idledown . Both of these mach's will idleUP when you strike an ark so they are essentially automatic . Lincoln , also makes 2 small welders and Neither has the Idleup feature to my knowledge. You won't get the full featured welding capabilities until you start looking at the "Bobcat" type welders from Miller and Others . All...3...manuf's make a Bobcat type machine around 2600 or so . Personally , I would contact the folks in the URL and visit with them about the Mit DC unit . I believe it would be a first class machine and since they are in Az. you probably wouldn't have to pay any sales tax which would more than offset the cost of shipping . fordy.. :)
     
  17. John Hill

    John Hill Grand Master

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    Dont forget PTO driven welders!
     
  18. idahodave

    idahodave Well-Known Member

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    I thought about doing the same thing....never tried it

    The answer from the Lincoln site sounds like kinda CYA

    You hooked it up and it worked right?...grab a couple pieces of say 3/16"
    steel and butt weld them together, stick them in a vise and
    break it. Let us know if you lay down a good bead

    No question about the gen running the buzzbox at 225 amps...no way
    but if you keep reducing the amp setting you should reach a point that it works
    just maybe so low that you couldn't weld sheep metal

    another thing that might make a difference is the engine speed....60 hz is just a target for the low end gen sets...changes in frequency willl alter the welding current delivered. If the frequency is low, less reactance so more current.