Need some help with some thin stuff

  1. Neil Aldridge New Member

    Messages:
    11
    Location:
    United Kingdom Midlands
    Ok so I’m welding 1mm sheet for small fuel tanks, i have my r-tech c315 mig on all its lowest settings with 0.6 wire and a glance at the voltage when running is about 15 volts and it sounds fine but i keep burning through, i can maybe do about a one inch bead on an open corner then burn straight through, there’s bloody bits of scrap all over the floor with crappy welds on and I’m slumped in the corner with my head in my hands blobbing like a baby!
     
  2. tom2207 Member

    Messages:
    1,568
    Location:
    uk northern ireland
    copper backing strip ,,, and rather than doing runs , do good hot tacs , overlap them and it will end up looking like tig.
    and do some more practice on your off cuts till you get the technique and rhythm right .
    Patience and practice.
     
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  3. cianh91

    cianh91 Member

    Messages:
    613
    Location:
    kildare ireland
    Try downhand welding it moving fast but as said above tacks or stitch’s little at a time
     
  4. Neil Aldridge New Member

    Messages:
    11
    Location:
    United Kingdom Midlands
    The copper backing strip wont work as its a fuel tank ie completely enclosed i did the last tank by overlapping spots but it wasn’t pretty deffo didn’t resemble tig and took a lot of dressing afterwards (ill add photos of that another day)
    I also tried downhand but i had to move so fast it was difficult to stay on the open corner and i still burned through (pics below) A0F8556C-C1CE-4644-BFF4-9DC218F0D8BE.jpeg 7AC2C5E5-74E7-4BE1-911A-AEA3BCAD2604.jpeg would upping the wire to .8 or 1mm help to reduce Heat transfer?
     
  5. GrahamGKD

    GrahamGKD Forum Supporter

    Messages:
    1,221
    Bournemouth UK
    There is a tutorial here - you should be able to make the multiple tack / stitch method look pretty neat with a bit of practice.
     
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  6. Dcal

    Dcal Forum Supporter

    Messages:
    1,994
    Location:
    Antrim Northern Ireland
    Do it down hill.
    Get the puddle going and keep on the leading edge of the pool and just keep in front.
    The rest will look after itself.
    If you go too far in front you will burn a hole, which I think is whats happening.

    If I was doing it I would use 0.8mm wire but you should be ok with 0.6.
     
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  7. Neil Aldridge New Member

    Messages:
    11
    Location:
    United Kingdom Midlands
    Thanks guys ill give them a go
     
  8. Neil Aldridge New Member

    Messages:
    11
    Location:
    United Kingdom Midlands
    Do you think using .8 as opposed to .6 reduces any heat transfer or is that just preference?
     
  9. Dcal

    Dcal Forum Supporter

    Messages:
    1,994
    Location:
    Antrim Northern Ireland
    0.6 should take less current to melt but the wire feed needs to be higher to get the amount of weld volume you need, so swings and roundabouts.
    I don’t get on with 0.6 and weld everything with 0.8, 1mm is pretty thick in the scheme of things.
    I've never welded at the lowest power settings in my life and don’t know how you would get a good weld if you did.
     
  10. tom2207 Member

    Messages:
    1,568
    Location:
    uk northern ireland
    weld the small end on last , and use a backing strip , if you cant hold it behind the joint use a stick as a packer
     
  11. eddie49 Member

    When I saw that you have an R-tech I thought it should certainly go low enough to handle 1mm. However
    • Nett weight 85KG
    so it is not an inverter

    and:
    • Welding range 40-315 amps
    This is a large 3-phase machine aimed at fabrication, the lowest current setting is too high. You need to use a machine with a low of 20 to 30 Amps.
     
    Last edited: Jun 4, 2020
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  12. tom2207 Member

    Messages:
    1,568
    Location:
    uk northern ireland
    use 1.5 steel ,,,
     
  13. Shedendman

    Shedendman Member

    Messages:
    4,231
    east sussex
    Agreed ^^^^^^^^^^^@eddie49
    Not only that from your photos you're doing an outside corner joint to,those aren't easy
    Forget long runs its zap wait,zap wait zap wait.............move elsewhere repeat
     
  14. eddie49 Member

    The minimum voltage you are seeing is quite low, but since this is a 300 Amp machine, the secondary windings and other components in the output circuit will be massive and very low resistance, so even 15 volts causes too much current for thin sheet.
     
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  15. Dcal

    Dcal Forum Supporter

    Messages:
    1,994
    Location:
    Antrim Northern Ireland
    I was in the garage and have an Rtec mig so thought I'd give it a go.
    Only 1mm sheet I have is galv so gave the edges a quick clean.

    Settings are 17.5v 4.2m/min

    IMG_2279.JPG

    Samples were 120mm long.
    3 tacks top, bittom and middle.
    Start at the top and keep in front of it.
    You need to be quick and confortable

    IMG_2280.JPG

    IMG_2282.JPG

    IMG_2283.JPG

    This was my second go and you could certainly dial it in and improve with practice
    Pulsing would also work and would be easier to control.
     
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  16. Shedendman

    Shedendman Member

    Messages:
    4,231
    east sussex
    No mention on what gas is being used here OP
     
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  17. slim_boy_fat

    slim_boy_fat Forum Supporter

    Welcome aboard, Neil :waving:
    That made me laugh out loud :clapping:, I think most of us [pros excepted] have been there at some point! :ashamed:

    Why did you think it would? :dontknow: Afaik, only the very best 'miggers' can achieved that. :scared:
     
  18. Matt Thomson

    Matt Thomson Member

    Messages:
    81
    Location:
    North Ayrshire, Scotland
    I found that overlapping spots certainly worked well on some 1mm sheet I was making Skydrol drip trays with. Being a beginner, I personally found it easier with the 0.8 mm wire, 3 stitch bursts and a damp cloth to take some of the heat out to stop it warping (which the first attempt did). A quick tidy up with a die grinder and twistloc pads had it looking pretty nice. It didn't take long to clean up at all. Might be worth a go that way? 20180830_104911.jpg
     
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  19. Feet 'n Inches

    Feet 'n Inches Out of the rat-race at last

    Messages:
    207
    Location:
    Devon, England
    Do you have the means to fold the steel or are you building it from 6 individual pieces?

    I made a 3 mm tank for an amateur stock car racer some years ago, folding two pieces of steel into a U shape and then joining them together. Filler and drain were cut out and welded before joining.

    Looks something like this quick sketch.

    tank.jpg

    Reduces the amount of welding and any distortion problems (bearing in mind it was 3 mm thick).
     
  20. Munkul Member

    Messages:
    2,091
    Cumbria, UK
    17 volts is too high - you want around 14-15 volts. Start at the lowest voltage it will set, and turn up until it's just burning acceptably. It depends a lot on the quality of the machine, though.
    Some machines will take a higher set voltage because it will droop more during welding.

    Personally I'd probably be spot/tack/stitch welding it, an outside corner seam at that thickness is hard!
     
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