More questions than answers

  1. Malky Member

    Messages:
    147
    Location:
    Scotland
    The more I find out the less I know.
    Have been quite happily buzzing along performing "farmers" welds for quite a number of years now oblivious to the fact that there might be more to welding than a shower of sparks, dipping into these forums for a wee while opened my eyes to the science behind it all, so a few questions and apologies if they are covered elsewhere.
    First one, never knew anything about wire speed creating the power requirement for the metal thickness and that I should find out the wire feed rate per minute so had a go measuring it.
    Question , is the wire rate/minute the same for all thicknesses ie. is 315 feet/minute the same whether its 0.8mm or 1mm etc. wire and is there a link to a table I could use as a reference to multiply the wire thickness by to get the amps ie. read on here 0.8 has the wire speed divided by 2, what are the others?
     
    Last edited: Aug 21, 2020
  2. BarrieJ

    BarrieJ Member

    Messages:
    636
    Location:
    Milton Keynes, Bucks, United Kingdom
    This from the forum files, which'll be a start but there are tables on Google - (other search engines are available).
    I'd be very concerned if my welder was spooling out 315ft per minute, I'm more used to 8' to 10'.

    https://www.mig-welding.co.uk/calculator.htm
     
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  3. Malky Member

    Messages:
    147
    Location:
    Scotland
    Thanks another misteak, 315 INCHES sorry.
    Saw this link and thats why I asked, seems to infer wire lengths MAY be similar and just 0.6-0.8, wondered if there was a bigger table for reference.
     
  4. frank horton

    frank horton V twins are great but 4"s rule.........

    Messages:
    2,234
    Location:
    Soon 2 B Crete
    just find some odments of metal, get em clean'd with a grinder and play with the knobs.....
    use just 1 size of wire then change once ur happy.....
    so much depends on outside sources as well....
    like working outside with the windblowing, what type of gas, how fast u pull the gun....
    try n find somewhere that does welding work and look thru the crack in the door.....
    90% of learning is just observation....
    it does take a while to learn and then there is welding car bodies.....
    which is a whole (parden the pun) dif ball game.....
    on a good day I'll use a wire speed setting and the next day it needs a tweek...
    it's all good fun...
     
  5. pedrobedro

    pedrobedro Man at Matalan

    Messages:
    10,717
    Location:
    CX Derbyshire
    Cheers Malky, I've got this stuck in my head now
     
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  6. daleyd

    daleyd Member

    Messages:
    7,107
    Location:
    Wrexham, North Wales
    Me too :laughing:
     
  7. Malky Member

    Messages:
    147
    Location:
    Scotland
    This is part of the problem as I said been buzzing around for a number of years now with a murex tradesmig, looking on the murex threads on here seems their main problems are mainly wire feed related, mine seems to have a very very sensitive wire speed control to the point moving the knob 1 mm will give a big jump in speed so would usually just turn the power dial up or down as required but often ending up burning holes or welding wire in the tip but thought all this was just parr for the course of a novice, reading on here I now know different of course. take it I'll get more help with this on the murex forums. I am now playing with 2 other welders to try wire speeds, power etc. both have amps dials but they don't move till an arc is struck by which time you have the helmet on and can't read the dials, whats the point of this?
    Also one has a toggle switch below the voltmeter marked "press to set o/c voltage" what is the point of this is it something I should be worried about?
     
  8. Malky Member

    Messages:
    147
    Location:
    Scotland
    HeHe another forum I'm a member of has a never ending tunes thread, running at over 320 pages now, gives you earworms all day long, good but sooooooooooooooooooooooooooooooooooooooooooooooooooooo damned annoying.
    Looks like you've just started one here:doh:
     
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  9. Robert Mullins Member

    Messages:
    112
    Location:
    Salisbury, uk
    If I were you, I would forget about how many amps, how many volts, what wire speed, and do it by instinct, if your not burning through, turn the volts and wire speed up, above 28 volts you'll be entering 'spray' transfer mode, and when you watch the you'll see the magnetic pinch effect on the wire, the wire goes to a point, but doesn't actually dip into the weld pool;
    With your machine set to pump 26/27/28 volts, turn the wire speed as high as it will go, and weld on a piece of scrap using one hand, with your free hand turn the wire speed until the wire starts to burn off in the weld pool, without banging, popping, or leaving reams of welding wire sticking out and doing a hedgehog impression, this should be somewhere near,
    Not enough wire allows the arc to burn off at the surface of the weld pool, with shallow penetration, the higher wire speed pushes the arc into and through the weld pool resulting in deeper penetration:
    One of several issues with mig welding is that the method can deposit a great deal of weld metal compared to the size of the arc, lack of penetration, cold lap, and lack of fusion are very common flaws encountered; the answer to this problem is? RUN IT AS HOT AS YOU CAN!! And remember, it is the arc that does the welding, not the weld metal, so keep your stringer narrow, weaving excessively will bridge the root resulting in incomplete fusion: if I've bored you then I apologise, I've been doing this welding for so long I can't understand why everybody can't do it
     
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  10. northwest

    northwest Member

    Messages:
    2,080
    Location:
    Manchester UK
    The best bit of advice I ever received regarding Mig was: You want it to sound like a Bee in a jar. I knew exactly what it meant and my welds improved no end.
    Not much help I know, but this worked for me.
     
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  11. Malky Member

    Messages:
    147
    Location:
    Scotland
    Definitely not boring, interesting thanks for taking the time to reply. I've been running on instinct for years its when you start reading these forums you begin to worry about all these cold, lack of fusion/penetration welds I've probably done over this time.
     
    Last edited: Aug 23, 2020
  12. Malky Member

    Messages:
    147
    Location:
    Scotland
    Another one, this dinosaur of a welder I have unearthed has a burn back control knob on the front panel, the remote wire feed box also has a burn back knob, is there a preference as to which one should be used?
     
  13. 8ob

    8ob Forum Supporter

    Messages:
    6,726
    Location:
    moscow on thames
    I would have a good look at this, wire speed is the critical tool for fine tuning a mig weld. It would be worth checking/blowing out the liner and making sure the rollers etc are all adjusted correctly. You wont make much progress with this welder until you get the basics sorted.

    Bob
     
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  14. Malky Member

    Messages:
    147
    Location:
    Scotland
    Thanks, its the fact that I now have other boxes to try that I realise there must be a problem with the murex, before just kept my head down(murex good make bad workman blames..............etc.). Have had the torch on the other welder and works fine, will check out roller/wire feed tensions shortly.
    murex tradesmig 245
    Asked on here, no replies yet, not even sure if theres a repair shop locally I could take it to.
     
  15. Robert Mullins Member

    Messages:
    112
    Location:
    Salisbury, uk
    Use either burn back knob, once it's set to how you like, you need never touch it again
     
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  16. Malky Member

    Messages:
    147
    Location:
    Scotland
    thanks for that, seems fine where I've got it now not had any welded tips anyway so take it it doesn't need reset every time the power settings change then, clever.
     
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