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  1. #16
    Join Date
    Jan 2004
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    Mackay North Qld
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    6,446

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    Almost invariably electrode welding novices seem to go to 1.6mm Wall Thickness and SHS and RHS to "practice " on. More than likely it is because the thin section material is cheap and will later comprise the components of their first project.

    It is very hard achieve for a beginner and deters many who do not take the time to understand the physics of burning an electrode .

    Trainee electrode welders are trained on thicker section stock for a damn good reason. One must first be able to control the arc. To practice those welds on an unforgiving sliver of metal is unproductive and not much is learned other than how to blow holes.

    Arc length and travel speed are big factors in affecting how much heat can be absorbed by the metal item being welded on.

    It is all very well to to say lower the amps but if this is done and the electrode arc length is in excess, the thin wall metal thickness takes in this heat and cannot dissipate it quickly enough and burn through soon follows.

    Add to this the travel speed if too slow promotes overheating and the same occurs.

    I say first learn and practice on a heavier wt metal first and perfect a short arc length ( with slightly higher amperage) and higher travel speed. When this skill is achieved,it is then far easier to transfer to thin wall tube.

    Also, a comment on smaller diameter electrodes. Have those recommending them used them?

    Apart from being more costly than standard gauge electrodes they are not easy to weld with as they have a narrow footprint and covering the seam is harder than it looks. They electrode being thin is harder to keep steady. I have found it is sometimes necessary to cut them in half to reduce the moving about.

    More on welding thin wall tube a bit later.

    Grahame

  2. #17
    Join Date
    Oct 2020
    Location
    Greendale Vic. Australia
    Posts
    64

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    Very helpful Grahame thanks. A little counter-intuitive really, that thin material is more problematic, but it makes perfect sense when explained.
    I feel a little better now, because my welds on 3mm steel are quite acceptable. So I'll keep practicing with stuff like that, and maybe go thicker too before I go back to try thin stuff.

  3. #18
    Join Date
    Nov 2004
    Location
    Bungama SA
    Age
    52
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    960

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    Yep agree with others stick on thin section is a PITA, using 2.5 6013's I tack every cm or so then between tacks this should give you enough metal to stand the heat soak of a continuous bead over top.
    Welding Galv is not good on thin section but it can be done, remember to wear a respirator!
    ....................................................................

  4. #19
    Join Date
    Sep 2005
    Location
    Bendigo
    Age
    60
    Posts
    419

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    Quote Originally Posted by Grahame Collins View Post
    Also, a comment on smaller diameter electrodes. Have those recommending them used them?
    Grahame

    Yes !

    But with any welding on thin wall, skill and practice is an advantage.

  5. #20
    Join Date
    Dec 2018
    Location
    NSW
    Posts
    586

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    Will attempt to burn some 2.5mm GP rods this weekend in MMAW-pulse using my TIG... Sure it can be done, just a matter of finding the sweet spot.

  6. #21
    Join Date
    Jan 2004
    Location
    Mackay North Qld
    Posts
    6,446

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    Some extra thoughts on welding thinwall tube.

    So far, in discussing the welding of thin walled square or rectangular tube no one has made comment on the welding joint configurations and the different techniques required.

    The techniques used for the configurations are important in conjunction with the arc length ,electrode type ,diameter and amperage selection.

    Irrespective of whether you welding rectangular or square tube the configurations that apply are the same for both of them.

    Two configurations

    1. Longitudinal butt
    2. Tee joint with butt joints and fillet joints


    No 1
    Both tubes are longitudinal on the same axis. Butt weld - end to end - edges to edges and no gap if cut square. a tack on each corner and Bob's your uncle. If your electrode / amperage/ arc length/travel speed parameters are all good , no problem.

    Thats the easy one, but now there is a different set up.


    No.2
    Something we will call a tee piece, and now there are two different configured joints on the same piece.

    Butt weld and fillet weld- perpendicular end to longitudinal section joint- Again, a tack at each end and a bead between the two. Oh! bugger! the cut edge edge doesn't butt up cleanly with nil gap because of that damn radiused edge on the longitudinal member.
    Run a bead down that sucker on the open cut end of the butt and for sure the arc will burn through instantly as there is minimum volume of metal to dissipate heat. The perpendicular end is wide open not even touching the opposite part meant to be welded to it.

    Time to re evaluate the procedure, then. The fillet portions will be easier to execute first.
    Being a close fit joint it is easier to manage and the bead/s will add some needed volume to the structure and its’ ability to dissipate heat.

    Quenching with water will not hurt.

    To finish off the open gap I like to build it up from the longitudinal closed side slowly quenching and eventually sealing the gap.

    If the joint does not need a complete seal just weld the fillets leave it as is.

    I have a bench built from 50 x 25 welded in this fashion.It is 26 years old and never moved.

    Grahame

  7. #22
    Join Date
    Nov 2017
    Location
    Geelong, Australia
    Age
    57
    Posts
    2,651

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    Another thing to consider if using a DC welder is polarity.
    Electrode positive puts more heat into the work and gives better penetration.
    For thin stuff using electrode negative gives less penetration and reduces the tendency to blow holes.

    Steve

  8. #23
    Join Date
    Dec 2018
    Location
    NSW
    Posts
    586

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    Quote Originally Posted by Commander_Keen View Post
    Will attempt to burn some 2.5mm GP rods this weekend in MMAW-pulse using my TIG... Sure it can be done, just a matter of finding the sweet spot.
    Tried something different with a pulsed stick weld on 20x20 1.6mm wall SHS. Butt joint welded mostly in the flat position. Lincoln easyarc 6013's in 2.5mm.
    Ran a 60A hot start for 0.1s (mainly to get a good arc strike).
    This then went down to an average pulse of 55A, set to 100Hz on a 20% balance on the 'hot' side of the pulse.

    Not my best work, and only had a few moments to dial it in (could have played with it way more), but an acceptable result for what the joint would require. Realistically I'd reach for the TIG or MIG if this was a job that needed any degree of speed or weld integrity.












  9. #24
    Join Date
    Jan 2016
    Location
    Gosford
    Age
    63
    Posts
    173

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    I've been welding some thin wall tube with small rods over the last few days. Interesting and challenging but a bit of fun.

    2.0 mm E6013 sticks on thin wall is very hard to direct onto the target. 60 year old eyes don't help. I also have just obtained a Bossweld 180 Inverter, (just for fun as it was a display model heavily reduced in price at the big shop). I can melt the electrode but when I put my eyes back in, the join is mainly still open with a few crossovers along the way. It takes several passes just to get a join. Slag is excessive as well with these small diameter rods. Even with stop and start, inclusions and grinding in between passes made me give up eventually and go to my flux core gasless MIG just to get the job going. Not worth using gas.

    I'm welding 2.0 mm wall tube so 1.6 mm wall would be very difficult. I can't imagine trying to use 1.6mm electrodes. I tried reverse polarity with the 2.0 mm rods but it was worse and I couldn't hold an arc. I haven't tried the AC transformer yet so that would be my next attempt at using these small diameter electrodes. I will keep trying although it's going to take some practice to master these wobbly things.

    I'm having no difficulty at all with the flux core wire on gasless and I've got some metal joined together now after spending a rainy day in the shed.


    Sent from my SGP521 using Tapatalk

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