Thanks Thanks:  0
Needs Pictures Needs Pictures:  0
Picture(s) thanks Picture(s) thanks:  0
Results 1 to 6 of 6
  1. #1
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,540

    Default Joining flat S/S sheet

    I'm welding some stuff for the scouts at the moment (I mean - what else would you do on a 34 degree day in the middle of your holidays?)
    As the request has been made by people who don't weld but have high expectations, some of the things asked for are proving to be technically "challenging". Most I've overcome but the one that has me worried is this -
    2 pieces of 304 S/S, 1.2m long, 0.4m wide (1.2mm thick). The desire is to join them so that they make a strip minimum 1.8 long, 0.4m wide. I tried this morning with the TIG but still have some distortion (I tacked around every 75mm before welding). I was going to cut it apart tomorrow and try again but am not sure whether I can get much better with the current method. What I think is happening is that the heat input while welding is expanding the material but because of the poor conductivity of S/S, it's just buckling locally rather than diffusing the heat. I tried something similar with some plain steel and while there is some distortion it is far less.
    Tomorrow's plan for improvement (home duties permitting) is to
    • Tack the ends together at a similar spacing but this time leave a slight gap so that any distortion of the edge of the sheet won't push up, and
    • Weld on a wet towel to try and suck any heat out of the sheet to minimise distortion and keep it flat.


    Anyone got any better ideas or tips/suggestions on how this should be done?
    The welder has a pulse setting. Would that help significantly? (I hardly ever use it so don't really know how much benefit it would be). The weld will be dressed back, so off the torch appearance is not vital (food prep surface).
    I tacked the two corners and then tacked the middle. Should I be tacking from the middle out perhaps?

    Michael

  2. #2
    Join Date
    Aug 2008
    Location
    Adelaide
    Age
    68
    Posts
    1,373

    Default

    Small tacks more frequently than 75mm and tack from the centre out with a gap between the two pieces. I use a slab of aluminium or copper clamped to the job as a chill bar (which also stops the back of the root oxidising if I can't back purge the work). Pulse may help to keep the heat down but requires practice (and be careful if any observers are epileptics!).

    Travel speed and keeping the amps down is important, you can also use thicker filler to drag some of the heat out of the pool as well. Are you using a gas lens?

  3. #3
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,540

    Default

    Thanks Gavin I'll try that.
    I'm not using a gas lens (although I have one somewhere). I think I have an Al slab or two around. Would probably work better than a wet towel (steam is the problem there).

    Michael

  4. #4
    Join Date
    Feb 2010
    Location
    Ballina, NSW
    Posts
    900

    Default

    I would try and clamp the butt join down really solid against a chill block. I don't know what metal you have lying around but if you had some 10mm aluminum plate to put underneath, then clamp some heavy angle iron on top of your sheet both sides of the join (use some thin aluminium sheet as a spacer to avoid rust contamination if needed). Then after I had it clamped down solid I would tack probably every 50mm and weld while it was all still clamped. The idea of the angle iron is so that you can still access the butt without taking away the clamps. You could flip the angle iron to point upwards if you think it might bend too much.

    I would also backstep weld between the tacks, starting on the inside, alternating sides until I'd finished.

    I think you'll still get some wrinkles this way. You need to decide if you want lots of small wrinkles, or a more even look but overall more distortion (in which case you'd weld it all in one run). Fully agree that minimising heat input is the key factor and pulsing will help. Not sure about using thicker filler though? that might ultimately slow you down, and I think the key is to weld quickly and keep the overall heat input down.

    Never had to do it before - just suggestions. So good luck.

    fitup.JPG fit2.JPG

  5. #5
    Join Date
    Jun 2005
    Location
    Helensburgh
    Posts
    618

    Default

    I guess it is doable but it will never look any good. Also depending on what grade SS carbon migration becomes an issue which depending on what it is to be used for might not be a big problem. If the weld starts to crack you have problems!
    CHRIS

  6. #6
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,540

    Default

    I had another go yesterday and the result was better - after dressing it was at least smooth although still had a slight dish in it. Tacking (30mm centres) was no problem but heat in when welding was an issue. I found doing small segments say 50mm long and alternating sides was the best. The chill blocks helped a bit but staying in contact with them was tricky. The bench set-up was a bit of a lash up so bolting things did not necessarily mean rigid.

    Thanks for the suggestions guys.

    Michael

Similar Threads

  1. VICTORIA Brass Flat Bar Assorted Sizes & 1/4" SWB Threaded Rod & 260 Carbide Brass Sheet
    By thumbsucker in forum METALWORK - Machinery, Equipment, MARKET
    Replies: 7
    Last Post: 18th Mar 2013, 03:36 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •