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  1. #1
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    Default Joint prep for stick welding skid plates

    Hi all. I regularly need to replace worn sections of skid plates from a slasher. The material is 75 x 12 MS. If I use a wide V it takes a lot of time, electrodes and heat to fill the gaps. If I try a narrower joint, I can't seem to keep the slag out. Any tips for stick welding a narrow V butt joint? It's not really a high-strength part, but I want full penetration because they usually wear paper thin before I get to them. Thanks.

    PS: I'm using an old AC Welder and my skills are a bit ordinary.

  2. #2
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    Hi Bryan, any chance of some pics of where, what and how your trying to weld, please. A picture can tell a thousand words, particularly if you can mark where you need to place the skid sections. The position of the weld, can dictate what needs to be done. No point in advising you how to prepare for a horizontal situation, when you need a vertical or overhead weld.
    If you need a hand PM me.
    Regards
    Kryn
    To grow old is mandatory, growing up is optional.

  3. #3
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    What size rods?

    For such a job I would probably use el cheapo $10 for 5kg chinese rods.
    Gold, the colour of choice for the discerning person.

  4. #4
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    Dont use 6013(satin craft etc)rods for thicker sections unless you want to V it out heaps and do 50million passes!

    Rods like 16TC or 18TC from WIA are better for thicker sections
    ....................................................................

  5. #5
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    A 70° included angle prep. Use 3.25 or even 4mm electrodes if the machine will run them. Leave a 3mm flat on the bevel base and you should peno through it with a 3.25.

    If not confident just do the skid as a whole unit and after the first run in the vee ,flip it over and back grind it with the A/grinder until you reach the original bead and run an electrode in it to fill the groove.

    I would intermittent weld the skids on for ease of removal next time around. As RC says use some cheapy electrodes -as it only mild steel. E7024 Geminis would be good enough.

    Grahame

  6. #6
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    If you're replacing them that often, is it possible to change them to be bolted on instead? Threads facing down to the wear surface so that the heads don't wear away, then each time you could just drill and tap the new piece of MS as required (and probably replace the bolts cause they'd be too short by now!). Probably quicker then cutting, grinding, welding every time?

    Or alternatively, what about running over the skid plates with some hardfacing rods intended for use on grader blades/bucket teeth? Might give you a lot longer intervals before having to replace them?

  7. #7
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    Hi guys. Thanks for the replies. In order:
    I will get some pics today.
    I'm using 3.2 rods. I'll check the box but they're just cheap GP ones from ebay - not 13s.
    70 deg sounds good. The 3mm flat, would you gap that or butt it? Because it goes around a corner I need to do it in 2 pieces so it kind of has to be done in situ, but I can get some weld on the back. I will follow the maker's stitches. It was designed for easy repair.
    I have suggested to the boss that we modify it for bolt-on replacements, but that sounds a bit too fancy to him. I'm hoping if I can get the method optimised, the weld repair should be quite economical. I'm interested in hard facing but I have no experience with it. I'm worried about distortion.

  8. #8
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    You can see where I've patched it before, but I need to go bigger this time.
    The rods are Gemini 12s.
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  9. #9
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    Think it was mentioned but e7024. Iron power rods will smash the metal down. For flat position only and a 3.2 rod will need about 150ish amps

    Sent from my SM-G900I using Tapatalk

  10. #10
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    Quote Originally Posted by brendanh View Post
    Think it was mentioned but e7024. Iron power rods will smash the metal down.
    I don't understand. Does that mean a lower profile bead, or a high deposition rate?

  11. #11
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    It dawned on me that the two straight joints will never wear through; only the angled one is an issue. Anyway I thought I'd prep at least one of the straight ones to Graham's spec, for the exercise. I aimed for a 1.5mm root gap because of a dim memory about half the material thickness. After grinding out the slag from the first attempt I realised I'd somehow fluffed the angle and it was closer to 50 degrees. Widened it out, tried again. Better, but still a small inclusion. By that stage I needed to stop playing and just get it done.

    Once I get some room I can lay peelers all day, but in a narrow gap I always get inclusions. You see flat welded to pipe all the time, so it must be possible. The only things I've found that help are smaller electrodes for the root pass, and tilting the job uphill. There must be something I'm missing.
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  12. #12
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    Quote Originally Posted by Bryan View Post
    I don't understand. Does that mean a lower profile bead, or a high deposition rate?
    Definitely high deposition. Once you set the amps right you can walk these electrodes on their flux cone and the slag will rooster tail off as it cools.

    Iron powder electrodes are capable of depositing up to 160% of the wire core volume. Almost 100% of the core wire ( theres a small loss due to spatter) and the rest is from iron powder ( surprise, surprise!) particles in the flux.
    Basically they are a down-hand horizontal /vertical rod- meaning a fillet with one member flat and other vertical or in your case a flat butt joint.

  13. #13
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    When I was teaching the unemployed to weld, I'd get them to hold the rod in the touching position, so that as the electrode burnt away it would move along the joint. I did this as the start procedure to prevent the slag inclusions, as they progressed, the electrode would be lifted up, getting the weld down nice and neat.
    Hope this helps,
    Kryn
    To grow old is mandatory, growing up is optional.

  14. #14
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    Quote Originally Posted by Bryan View Post
    I don't understand. Does that mean a lower profile bead, or a high deposition rate?
    High deposition rate. You can get slag inclusion on starts, similar to 6013 so you need to watch that.
    Im not sure how deep they penetrate, and if your running on ac the peno will be less then dcep. Depending if you need a full peno weld or not a root run with a 6011 might be a good idea. It mighy even help on the tight sections you where talking about.

    Sent from my SM-G900I using Tapatalk

  15. #15
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    Quote Originally Posted by brendanh View Post
    High deposition rate. You can get slag inclusion on starts, similar to 6013 so you need to watch that.
    If there is slag inclusion on a 6013 start, I would suggest that the electrode has not been set with enough amps and it is being held with the arc length too long. Good penetration is a function of the arc length being held short. For a start or restart go downstream a couple of wire diameters ,strike arc ,lift 6mm or so and scoot back to the start point with short arc.This brings the metal to welding temperature and a good start results.

    If one were to do a cut and polish test comparing the two different electrodes penetration I doubt if you could discern the difference.
    Its all about fitness for purpose-there is no great load on the skids- just abrasion.

    Grahame

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