thicker plate to 4mm box vertical

  1. Richard.

    Richard. Forum Supporter

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    Your best ones yet imo.
    Look great.
     
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  2. Brad93

    Brad93 M J B Engineering

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    Much much better!
     
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  3. smashweld Member

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    ....decided to do the BFH test on a test piece this morning.
    Where would you want it to break off?
    After hammering the angle back n forward a few times it broke off at the edge of the weld...the HAZ?
    Ideally what should happen when conducting these scientific tests?!
     
    • IMG_20180116_101752.jpg
    • IMG_20180116_101744.jpg
  4. Richard.

    Richard. Forum Supporter

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    Weld should break ideally along the HAZyes.
     
  5. smashweld Member

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    Cheers Richard.
    Was thinking I'd read before that shouldn't happen but must be getting mixed up with something else
     
  6. Richard.

    Richard. Forum Supporter

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    Looking at where that broke it’s exactly where I’d expect anything sound to go first. How sound is a different matter. If it broke along the haz too easily then you’ve potentially wrecked the mechanicals of the plate with an oversized grain structure in the haz. However if that took a significant amount of force then it’s a job well done. A BFH isn’t the best way to judge this though as you cannot really measure force too well. A bend test would be a far more suitable way to determine how sound it actually is.
     
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  7. Instructor_Nige Member

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    Dam that is one beautiful looking weld there backpurge.. that's weld porn that is

    Nige
     
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  8. paulmitchell1984 Member

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    Fancy teaching me to weld haha...looms good and neat..verticals arw my enemy lol
     
  9. smashweld Member

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    IMG_20180207_152836.jpg Similar to my original post....

    Got some weld on trailer brake backing plates to do...
    45mm diameter axle to 5mm thick backing plates. ...been experimenting with the old plates that's been cut off with some 50mm solid bar.
    Struggling to get penetration in to the bar without the weld being massive on the bar side of the join.
    Its a 250 mig...weld just sits on top of the bar unless its almost at the highest setting.
    No acetylene just now but would preheating help much? Is it even possible with the mig without preheating or some other prep?

    Any thoughts welcome!
     
  10. Richard.

    Richard. Forum Supporter

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    Good fusion on 50mm bar isn’t really going to happen with dip transfer vertical up mig (110-130amps 18-20v roughly.)
    If it’s a job that cannot be positioned into the gravity position then I’d possibly be looking at a dual sheild flux core.
    This will weld in all positions in a spray transfer.
     
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  11. smashweld Member

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    Cheers Richard....I dunno what those are tbh!
    Do you mean just different wire or a different welder too?
    Another thought...
    Would a stick welder do it?
    I went digging this out..not been used for 20 odd years....do you think it will do before I start putting ends back on the cables?

    Btw...The axles could come off to weld on the flat but ideally want to leave them in place
    IMG_20180207_162608.jpg
     
  12. Richard.

    Richard. Forum Supporter

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    Oh of course. Mma (stick) would be perfect if you have that process available. Dual shield flux core is a flux core wire for your Mig. It essentially is stick welding properties in a mag wire.
     
  13. smashweld Member

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    There's actually two of these welders here...oil filled/cooled?
    This old stick welder must have been used more recently than I thought...it used to be used in another shed with older bigger style plug. Never noticed the blue plug on the short lead.
    20-220amps it says. What sort of thickness of mild steel is that good for?
    Out of interest would it be good for stainless too?

    Sorry all the questions...looking forward to using it tho!
     
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  14. smashweld Member

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    another thicker to thinner question...

    thoughts/how would you tackle these? wedge shape hinges/locking bar tab to 5-6mm box

    IMG_20180227_155129.jpg
     
  15. Brad93

    Brad93 M J B Engineering

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    I would of ground the lugs and the box section back to clean metal for starters.
     
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  16. smashweld Member

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    :ashamed: ok that's pretty fundamental!

    would you usually use multiple passes/preheat?

    was thinking starting at the thin end of the wedge would be better so there's more heat by the time get to the thicker end
     
  17. smashweld Member

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    been reading this https://ewi.org/gas-metal-arc-welding-basics-travel-speed-and-contact-to-work-distance-ctwd/

    looks like I have misunderstood something fairly important....

    I thought if you stay in the puddle then it produces more heat and burns in to the metal more... but what actually gives better penetration is when the arc is at the leading edge of the puddle!? That explains the whole vertical up vs down thing.....the way I understood it was the puddle is dropping faster going down so less time to stay in the puddle and let it burn in!

    so for thicker stuff on the flat best to turn the power up and move quicker?

    edit - actually...just been reading this now... so does this only apply to stick welding? (I was shown how to weld on a stick welder...'self taught' on mig, maybe why I think like this)

    http://www.lincolnelectric.com/en-g...-theory/Pages/variables-weld-penetration.aspx

    Travel Speed: how fast the electrode travels down the joint affects how much time the arc energy has to transfer into the base plate at any particular point along the joint. As travel speed increases, the amount of time that the arc is over a particular point along the joint is less and the resulting level of penetration decreases. As travel speed decreases, the amount of time that the arc is over a particular point along the joint is greater and the resulting level of penetration increases (see Figure 6).
     
    Last edited: Mar 3, 2018
  18. Brad93

    Brad93 M J B Engineering

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    It applies to all forms of welding.

    You always need to be on the leading edge of the puddle for maximum penetration. Mig welding is one of the worst for lack of fusion discontinuities due to people not being on the leading edge.
     
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  19. Richard.

    Richard. Forum Supporter

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    It’s also good at telling lies. Mag runs can look stunning (if I ain’t welded them that is :laughing:) yet can hide the fact it hasn’t fused the metal in much the same way I can hide a big bar of galaxy from my kids and keep a perfectly straight face :D
     
  20. smashweld Member

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    ...not stunning but I can definitely make welds look decent with MIG but know they're rubbish after they come flying off after a few hits with the hammer!

    I take it the bit I quoted on the lincoln site about travel speed is correct but just doesn't say that it's possible to go too slow
     
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