Open root bevel joint problem.

  1. heinz57

    heinz57 The Wannabe Welder!

    Posts: 118
    England
    I've been stick welding at college for a couple of weeks and have done some nice welds on laps, t's and vertical down welds. But I can't master the open root bevel flat position.

    The material is either carbon or mild steel, from 5 to 10mm thick, i use a 2.5mm gap and raise the work off the bench slightly. I have a root face of about 1.5mm and use a 2.5mm electrode (6013 i think) the amps are about 80. I get penetration and the slag underneath the weld just drops off nicely but its a bit wavey and sags in some places and not in others. The top of the weld sits nicely in the grove but there's lots of slag inclusions and thats if i can even get the slag off, it seems to resist a fair bit.

    The technique i use is to move the electrode straight down the work slowly my arm parallel and then whip it back to prevent keyholing every 2 secs. I've tried this technique but no joy. Can anyone suggest technique or point me to a video, cheers.
     
  2. Delgado Member

    Posts: 369
    Slough UK
    I've not done tons of open root stuff with MMA, but I think maybe your amps are a little high, try turning them down to about 70/75, personally I like to have as little keyhole as possible, and I wiggle the electrode slightly from side to side in the gap as I see/feel the rootface breaking down. If the keyhole starts getting too big then you could make the electrode angle flatter (so that the heat is pushed back into the weld pool and not into the keyhole) and give it a bit of a quick weave whilst increasing your travel speed, then change the angle back to almost vertical when it closes back up to the size you want.:welder:

    At any rate, it aint easy but I'm sure you'll get there with a bit more practise.

    :welder:




    As I said, this isn't something I've ever had to do much of (so don't look too closely:laughing:), but I had a bit of a play in the workshop a minute ago using your set up but with 72amps and 6mm mild steel. The stop/start is a bit dodgey, as in my haste I didn't feather it properly, and it has a little bit more root reinforcement than I'd like (not clear from the photo but it's about 3/4mm);

    06102010069.jpg

    PS, might also help to increase the root face to 2/2.5mm, but I guess it's down to personal preference.
     
    Last edited: Mar 10, 2011
  3. It is tough and i know exactly what you are having trouble with, i started a college course last september and did the open v butt test first, luckily for me i have been welding for 18 years so the open v butt was easy to me but one of the other guys still can't get it right even now, i have set it up and checked it for him and even watched him but still he can't get it, unfortunately it's not an easy fix, you're doing it right but the trick part just hasn't clicked in you yet, it will though trust me, one way to help a lot would be to ask the tutor for a 7016 rod instead of the 6013, the 7016 rods are fast freezing low hydrogen rods so basically they will freeze much quicker on the underside than the 6013's would and that would stop the excessive root beading from forming, the college you go to will have a stock of these but they won't let them out to everyone because of cost however if you're serious about welding as a career then your tutor should let you use these rods because when you are welding for a living you will use 7016's for root passes 9 times out of 10.

    One piece of advice i can give you if you have to use the 6013's is to keep the arc as short as possible, dipping in and out making the arc length long and then short is what is causing the dripping on the underside, consistency is key, whatever travel speed and arc length you start your run with is what you should finish it with too so that you leave a nice even bead on the underside.
     
  4. heinz57

    heinz57 The Wannabe Welder!

    Posts: 118
    England
    Thanks fellas! There are some 7016 rods available im sure, but for budget reasons they generally only provide 6013's as im told it's a good all rounder
    AC/DC all position rod. There is a rod oven so im guessing there are other rods available. I'll ask and see if i can give it a go with the 7016.
     
  5. As Steve says, keep as short an arc as possible and move quickly but consistently
     
  6. Lewis Medlock

    Lewis Medlock Member

    Posts: 241
    Hereford
    I spent bloody ages trying to nail the arc butt at school, I tried every bl**dy rod and loads of variations of root face/gap and either blew a whopping great big hole or failed to penetrate.

    I finally got it with a 3.2 7016 and lots of stubborn determination (coming quite close to throwing things about the workshop!)

    Here's my effort
    http://www.mig-welding.co.uk/forum/showthread.php?p=190064#post190064

    All the best, Jim
     
  7. cookie munsta

    cookie munsta Member

    Posts: 175
    australia
    If your running a 6013 at amps then your too cold for 8mm and up plate.
    it will tell you that it is within range and it is, but slight variations in hand movement will affect it. start at 100 amps and adjust to suit, and be confident. a confident state of mind is a steady state of hand, if you screw it up you should have a consistent example in which to determine fault and improvement as opossed to picking through a inconsistent mess for what went wrong. I hope:welder: it helps keep us updated
     
  8. heinz57

    heinz57 The Wannabe Welder!

    Posts: 118
    England
    Cheers Jim, i hear what you're saying, thanks for the pics!!
     
  9. heinz57

    heinz57 The Wannabe Welder!

    Posts: 118
    England
    I was in the 70 amps range and it keyholed quite easily if i wasn't careful. I think 100 amps is gonna be way hot, what technique would you use at 100 amps?

    The machine is an old AC, pickenhill or something. Cheers.
     
  10. cookie munsta

    cookie munsta Member

    Posts: 175
    australia
    How thick is the plate? if you start at say 100 for 8- 10mm plate and adjust either up or more likely down. make is material is clean of cutting oils rust etc, root face of 1.5mm and root gap of 1.5 -2mm. Most of the welders I've used are fairly newer so their amp settings are reliable. 70 amps just sound a bit cold to me but if its working
     
  11. heinz57

    heinz57 The Wannabe Welder!

    Posts: 118
    England
    I found something out yesterday about the pickenhill welder that we use. It hasn't been calibrated in about forty years!!!:o

    I was using a 2.5mm 6013 rod on 180 amps dcep!!! and it welded 10 times better! I started laying down some nice root welds on 10mm mild steel. I had the rod at about 70 degrees pushed into the root and dragged it back
    (or pulled it) and whipped the rod as suggested every 10mm or so just behind the crown of the molten metal, actually i think its more of an upward horizontal flick rarther than a lifting motion but that's just me.
    I will be back in the bay today doing nothing but this technique until i get it 100%. I find that without the flicking motion on a 6013 rod i get a massive slag inclusion down the underside centre of the weld. I did try a 7018 rod as well, but just the one. I'll try and lay my hands on some more
    and report back. Thanks to those who replied.:clapping:
     
  12. As you get more experienced you tend to ignore what the dials say and set the machine according to what you see through your screen
     
  13. heinz57

    heinz57 The Wannabe Welder!

    Posts: 118
    England
    Cheers Backpurge.

    Can anybody help me answer this one?
    If i'm doing an open root bevel joint and i'm using a 2.5mm electrode, what size should the root gap be? I've been using a 2.5mm gap with a 2.5mm electrode and i'm not getting penetration a lot of the time. If i increase the amps then i burn through. My speed can be faster or slower but i still get the same problem.

    Any ideas fellas? cheers. :mad::mad::mad:
     
  14. Lewis Medlock

    Lewis Medlock Member

    Posts: 241
    Hereford
    I've just got my vertical Arc butt marked at school, it's taken 4 MONTHS!! of Wednesday afternoons (and some practice in my own time) to get there :o

    The test piece got a distinction with a "capping run appears rough" note, I was delighted!



    Not penetrating means the root gap isn't big enough, or it's closing up as you develop the weld, or the arc gap is too long.

    Blowing through is either too many amps, too big a root gap or most likely too small a root face.



    I had exactly the same problem (not penetrating or blowing through). I finally worked out that I was so concerned with blowing holes that my arc gap was too long, this led to no penetration.
    I got really bold/brave and stuffed the electrode right into the root prep which kept a nice short arc length. It sounded awful, like I was blowing holes, but did the trick.

    Be bold, have a decent root face - which enables you to have a decent root gap and confidently stuff the electrode deep into the root :)

    I used about a 2-3mm root face with about a 3mm root gap at about 70 amps with a 2.5 6013 "Superblue" electrode.


    Best of luck to you :welder:
     
  15. Lewis Medlock

    Lewis Medlock Member

    Posts: 241
    Hereford
    Without moving too fast

    Jim
     
  16. heinz57

    heinz57 The Wannabe Welder!

    Posts: 118
    England
    Thanks for that Lewis, i'll make a slightly bigger root face next time i try and congrats on passing your weld test mate! :clapping:
     
  17. When I did my course the Vee Butt root was always in 7018. As we were using AC transformer sets it was a b****r to get them running. They run nicely on DC at home! The 6013 that subsequent passes were done in were far easier by comparison
     
  18. heinz57

    heinz57 The Wannabe Welder!

    Posts: 118
    England
    Yeah, 7018's seem to run better with about 50% arcforce as it's a low penetration rod and ac does give off some splatter. :welder:
     
  19. Lewis Medlock

    Lewis Medlock Member

    Posts: 241
    Hereford
    How's it going Heinz? I bet you're bored of grinding bevels on plate ;)

    Jim
     
  20. heinz57

    heinz57 The Wannabe Welder!

    Posts: 118
    England
    Hi Lewis, I cracked it mate!!!

    I can now do open root bevels in my sleep :clapping:.

    It's all about digging in the rod and turning up the arc force even with a 6013 rod! Works for me. I tried using a bigger root gap (3.2mm) and it worked nice, then after numerous attempts i went back to a 2.5mm gap and got my mojo going!:D

    I'm now working on vetical bevels, my first one was a pass, it seems much easier although i still need lots more practice.

    I just tried vertical t joints and im trying to find what works best for me there, i learnt one thing straight away and thats use much less current - wow. Just going to concentrate on that for now, how's yours comming?
     
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