Criticism please!

  1. Will! Member

    Messages:
    98
    Location:
    Derby - England
    Ey up, I joined roughly forever ago, then never actually got around to welding my car up. Life got in the way. I have however decided to weld up a skate rail as a bit of faff to do over the weekend - cheap thicker material is probably somewhat more forgiving anyway. Probably the first serious welds I've done in 'ever'. There's a bunch I'm not totally happy with though, can I have some criticism please?!

    Machine is a Clarke Pro 90 (not the EN one), set to max and wire on '7', whatever that means in volts and mm/min. 0.6mm wire. CO2 gas, at about max on the tiny disposable gas bottle regulator.

    Plate is about 6mm I think. Straight butt welded, no prep - partial penetration, I welded both sides.
    The RHS is 3mm, ~1mm land, 45° bevel (eyeballed with an angle grinder).

    I've tagged the more obvious defects, things I don't like.

    A - I finished here and went back a bit with the bead, I presume this is just cold lap caused by doing that, and doing it too fast.

    B - funny stringy bits at the toe, no idea why.

    C - Porosity but I'm not sure why. I was welding outdoors but there was no wind at all. A bit of dirt on the steel that I missed?

    D - Loads more cold lap. I was weaving a bit on the fillet, dwelling on the top toe, is this caused by not dwelling enough on the bottom toe?

    E - More cold lap. Travelling too fast? I notice it's necked here a bit.

    F - Welding around a corner. Should I have been starting on the corner, welding the length of one side and finishing on the next corner so all of my welds were straight without manipulating the torch too much?

    G - More cold lap again, see D.

    Any other advice?

    Thanks!

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  2. minimutly Member

    Messages:
    1,488
    Location:
    Pembrokeshire Wales
    You're doing well with that welder!
    It's too small for what you're doing though, so cold lap is no surprise. You need a bigger welder...
    And get a pub gas co2 bottle as well, better still argon/co2 mix.
     
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  3. barking mat

    barking mat Barking at Pigeons

    Messages:
    4,605
    Location:
    Brittany, The Arz Valley.
    No prep!

    Go on give it a fiddle with an angle grinder.

    Failing that, not too bad frankly.

    In my eyes!
     
    addjunkie likes this.
  4. Munkul

    Munkul Jack of some trades, Master of none

    Messages:
    3,144
    Location:
    Cumbria
    Doing well enough. Your faults are mostly related to the physical limitations of your machine.

    You need more amps (wirespeed) BUT that machine simply isn't capable of supplying enough current or voltage. Especially on those box section fillets. You should have at least 140 amps for those joins.

    Technically you're not supposed to stop on a corner - you're supposed to go around it like you have done, and the stop/start join on a straight. Most people just stop-start at the corners though, unless its something critical.
     
  5. Will! Member

    Messages:
    98
    Location:
    Derby - England
    Thanks all. I got the machine on the basis that I was only ever going to do thin sheet with it and it'd just get an MMA set for thicker work because I'd be welding outside anyway - except I never bothered to get the other one.

    I'm off out to get some Ar/CO2 in a bit, if I get time later, I'll post some photos of the other welds I've yet to do.
     
  6. Will! Member

    Messages:
    98
    Location:
    Derby - England
    Here's a couple more with 14% CO2 mix instead of 100% CO2 (disposable again, I've only got three welds to do then it probably won't come out again until next year).

    I did all of these in some convoluted position on the floor, rather than at a bench - that was a new experience.

    First - Cold lap again, can I solve this by dwelling at the toe a bit longer or is it just a case of there being no way I'm welding 3mm thick section with a 90amp welder without getting cold lap? Huge blob at the end because I couldn't get myself into a position to go around the corner.

    Second - There was some wind today, I think this regulator is at its limit. I'll probably repair this bit because it offends me. The restart was poorly placed as well.

    Third - Looks such a mess because the fit up was garbage, I didn't actually notice until I got around the corner. I used a lower voltage setting to build up a bead on the tube to close the gap, then ground it back so it didn't protrude much, then went over it. The tie in with the previous bead was poor again, this welding around a corner lark is harder than I expected, even after doing some dry runs to test the range of motion.

    Other things I've learnt:
    The gap between the highest voltage and the one below on this machine is huge, one step down and it barely even melted the parent metal - probably because even maximum was too low.
    My automatic visor is too dark when off to actually see what I'm doing sometimes.

    On another note - These welds were very sooty around the toes, parent metal was cleaned with an abrasive wheel, is it likely that the wire is dirty? The actual bead was clean.

    Any more advice (other than buy something more powerful / a new regulator) would be appreciated.

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  7. Lordspectre

    Lordspectre If it aint broke, tinker with it anyway

    Messages:
    212
    Location:
    Ireland
    In terms of the machine ya have dude ya didn't do bad as at all. Ya cleaned the material and did alright in regards to the gas too much is as bad as too little but it's probably a bit of dirt that got in the way. You would need a welder capable of about 150 amps to give th t thickness of material a good go but as said ya did well with what you had. Chamfering the ends off the 2 pieces of material your welding togehter would help a bit in regards to penetration and building up the size of the weld but still a better machine is the way to go.....Xmas is a coming
     
  8. Will! Member

    Messages:
    98
    Location:
    Derby - England
    I neglected to comment on the prep - 45° chamfer on the RHS, 1mm land. Same as the first post.

    I think it's MMA inverter time if I make another. Applying a MIG welder to outdoor welds is definitely a sub-optimal tool for the job, regardless of amps.

    I had a couple of tacks that were basically metal Aero bar before I built a cardboard fortress around where I was welding, it didn't take much to make a mess of it.
     
    Lordspectre likes this.
  9. Lordspectre

    Lordspectre If it aint broke, tinker with it anyway

    Messages:
    212
    Location:
    Ireland
    Sometimes a workman can blame his tools the MMA do you the right job next time
     
  10. barking mat

    barking mat Barking at Pigeons

    Messages:
    4,605
    Location:
    Brittany, The Arz Valley.
    I've seen much worse...
     
    mtt.tr likes this.
  11. Nauticus

    Nauticus If l let my mind wander, its often gone for weeks!

    Messages:
    90
    Location:
    Lincolnshire, UK.
    As mentioned here before by Lordpectre, too much shielding gas is usually just as bad as too little shielding gas.

    The higher velocity of the shielding gas leaving the nozzle has a venturi effect on the surrounding atmosphere, dragging oxygen and nitrogen etc. into the gas steam and seriously diluting it.

    Get a 'Peashooter' (less than £10) to check your gas flow accurately at the nozzle, Set your flow somewhere between 6 and 10 litres per minute. (I manage quite happily on 6 but others here have quoted higher rates). Experiment at different gas flows to find the best rate for you and your current machine. Get into the habit of checking your flow each time you start a welding session. You need the lowest flow without getting porosity.

    Creating a barrier to prevent draughts around the immediate welding area is far more effective than jacking up the gas flow - since the venturi action of a high velocity of shielding gas leaving the nozzle will cause dilution of the shielding gas shield - and that is exactly what you are trying to avoid. Even a gloved hand cupped around the welding point helps.

    Malc.
     
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  12. DAPPH

    DAPPH as dyslexik as I'm daft

    Messages:
    2,873
    Location:
    Near to Cross Hands Llanelli SouthWales GB
    Thanks for the words about higher gas flow , I think I may have been having mine too high at 10 l/min & got welds that could have been better .
     
    Nauticus likes this.
  13. Ed. Member

    Depending on the torch, if it is a small torch 10l/min should not be be an issue, on my large torch I run about 12-14l/min depending on whether I am outside or not. The smaller torch I run at about 10l/min. Generally I do a test sample, if porosity occurs then I up the flow, if not, good to go as is. I would also make sure that the nozzle is also clear of splatter as sometimes a bit may fall off during a weld and it will contaminate what would be a normal good weld bead. Porosity and contamination will give you a similar result so need to check.
     
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