Attempt to Tig Auminium

  1. doggone1 Member

    Messages:
    70
    uk
    picked up a Castotig 3002 locally and thought id have a go on some thin ally sheet first attempt was pretty dire and using a filler rod very quickly second attempt seems much better starting to get used to it a bit more adding less filler and speeding up a bit also getting used to lift start as hf doesnt seem to be working not sure whats happening at the end of the weld initialy I was lifting the torch away as soon as i finished but am leaving it threre for a few seconnds now also on my first attempt I was starting before the weld pool had formed.
     
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  2. pressbrake1

    pressbrake1 Forum Supporter

    Messages:
    1,801
    essex england
    Keep going and suddenly it will be easy
     
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  3. Hood

    Hood Forum Supporter

    Messages:
    9,989
    Location:
    Carnoustie, Scotland
    The second lot look pretty decent for the first few attempts.
    Clean material is a must and plenty of practice will get you doing some nice welds.
    You seem to have a decent rhythm going by the spacing :thumbup:
     
    Hopefuldave likes this.
  4. doggone1 Member

    Messages:
    70
    uk
    Thanks for that I need to work on the weld finish I think I can get the rhythm better I was practicing on some 1mm 1.5mm sheet that was kicking around would it be worth getting the hf fixed this is only a hobby for me and dont seem to be getting to much contamination with lift start last time I did gas welding was about 40 years ago on a rusty escort van when I let it down of the jacks bloody doors wouldnt shut properly
     
  5. Hood

    Hood Forum Supporter

    Messages:
    9,989
    Location:
    Carnoustie, Scotland
    HF is much nicer to use but you won't, or shouldn't, get contamination from lift start. Scratch start is different as you can get contamination with it.
     
  6. doggone1 Member

    Messages:
    70
    uk
    Thanks Ill leave as is then seems to weld very well apart from the operator would love to try hf to see the difference
     
  7. b4lamb Member

    Messages:
    26
    Location:
    Wales, UK
    There should be no reason HF start should not work on a.c. and aluminium. Sometimes I have to touch the tungsten down and then raise before pressing the HF start switch. It's like it needs to equalise the static voltage potential between the tungsten and the workpiece before HF start will work. Not every time but once in a while.
     
  8. Gazello Member

    Messages:
    57
    Location:
    Bavaria
    The hf does nothing on ac at Older Fronius it uses a extra 400v pulse to reingnite the Arc During welding only the Start gives hf Puls , that why it Is so silent at ac , Same Prínciple Uses Rehm Tiger and Lincoln v205t
     
    doggone1 likes this.
  9. doggone1 Member

    Messages:
    70
    uk
    Had another go this evening I am getting more confident with starting and the weld pool forming and adding filler so I havnt been practicing this but concentrating on getting the end of the weld right but Im still getting a crater I am using a foot pedal ive tried lifting of the amps and adding more filler but still seem to be getting a crater even though it is a lot smaller than my first attempts some are better but the filler rod has stuck to a couple where ive removed it to late
     
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    Last edited: Oct 24, 2019
    b4lamb likes this.
  10. b4lamb Member

    Messages:
    26
    Location:
    Wales, UK
    I wouldn't worry too much about the crater at the end of the run as this can be touched in on a second spot weld. A crater is normally controlled by having a nice slow taper of current on 'button' or 'pedal' release that you can set up on your TIG set (ramp down) so you don't have to control this with your foot pedal.
    I see you don't have a very wide clean width but at least you can see it so its fine for very clean Alu. I would tent to want to increase that a little (positive to negative ratio). The brown staining on some of your runs is usually caused by bridging the arc with the filler wire momentarily or trying to add filler before the puddle forms.
    I would move on to practicing lap joints and then a corner fillet now you can lay beads and then some butt welds last.
    You have not mentioned the difficulty of striking an arc at start up so it sounds like you have overcome that?
    What is the underside of your plate looking like?
     
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  11. hotponyshoes Member

    Messages:
    1,711
    Location:
    Somerset. Uk
    I dont know if it's the proper way to deal with ot but I find that you can lift off with je pedal at the end of the weld but still keep the arc going, then let it cool a bit and you can see the crater form, then give it a quick dab on the pedal with a bit more power and put another dap of filler into the crater to fill that in.
    Off the pedal to break the arc and hold the torch in he same spot so the end of the weld cools under the post flow gas.
    If you have enough post flow for the weld to solidify while the gas is still flowing it's easy to press again if you need to restart the arc and add a bit more filler to loose the crater completely.
     
    b4lamb likes this.
  12. doggone1 Member

    Messages:
    70
    uk
    Thanks for all the advice Ive turned the cleaning up a bit and this has helped striking the arc is getting better and the underside seems to have good penetration ill get some pics tomorrow.
    Ill have another go at the crater with your suggestions and see how I get on i have been using the foot pedal and this puts the machine into 2 step mode reading the manual it seems crater fill down slope only works in 4 step I guess because you control it with the pedal.
    Ill try without the pedal in 4 step mode and see what happens then move on to some butt and fillet welds my first real job for this will be to tig braze a repair to a mudguard for an RD350 im restoring prior to chrome seems to be the preferred method of repair by chrome platers I did try with mig but this didnt turn out good enough for chrome as it needs to be perfect prior to chrome any suggestions on braze or better options
     
  13. doggone1 Member

    Messages:
    70
    uk
    Had a busy day but managed to get 15 minutes in this evening I tried a but weld and was surprised how hard it was compared to laying a bead on top for some reason I had the ally plate laying on top of some steel.
    I concentrated again not so much producing a good weld but getting rid of the crater and im getting the idea now just need to practice more.
    With regards to the welds some where done with a contaminated tungsten I was using a 1.6mm but had the welder set on about 3.2 to see how it affected my lift starts and they were not good I think having the tungsten size set wrong was maybe the reason as they were fine the other day didnt realize till later so will try again with it set correctly
     
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  14. Brad93

    Brad93 M J B Engineering

    Messages:
    6,622
    Location:
    Essex
    Why are you using lift start?
     
  15. doggone1 Member

    Messages:
    70
    uk
    My hf doesn't work unfortunately
     
  16. doggone1 Member

    Messages:
    70
    uk
    couple of samll runs trying to get rid of the crater what do you think
     
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  17. Hood

    Hood Forum Supporter

    Messages:
    9,989
    Location:
    Carnoustie, Scotland
    They look too cold to me.
     
  18. doggone1 Member

    Messages:
    70
    uk
    Thanks Ill turn the amps up a bit penetration underneath wasnt great did the end of the weld look ok thats the bit im strugling with
     
  19. Hood

    Hood Forum Supporter

    Messages:
    9,989
    Location:
    Carnoustie, Scotland
    The craters are definitely less pronounced than previously but that could well be because the weld was cooler to start with.

    Personally I wouldn't get too hung up on it as it will come with experience.
     
  20. b4lamb Member

    Messages:
    26
    Location:
    Wales, UK
    Your butt weld did not penetrate to the rear probably because your steel backing plate bridged the gap between the two plates you were welding. This is a no no. You should always leave a gap on the rear. By all means use heat sink bars or plates to the rear but leave a gap between them at the joint position about 10 mm wide I.e 5mm either side of the join. If this was the case and you did leave a gap then you are running to cold. You should be looking to see a moving keyhole that you constantly keep filling with filler rod.
    TIG brazing is not simple but ideal to prevent distortion. Getting the current setting correct and absolute cleanliness is the key areas to concentrate on. Welding sets are designed to weld not braze so making sure the arc is not melting the steel is of importance. Unlike using a gas torch the arc temperature is much hotter so you are relying on heat dissipation in the parent metal and braze rod dips to be high enough so that it prevent excessive local heat build up.
    Re tungstens, I always use the next size up for the current rating when ac welding as the tungsten tip heats up much hotter due to the a.c. balance setting. That's why the tip balls when a.c. welding. I'd use 2.4 mm tungsten for the thickness alu plate you are welding and I would use white tip zirconiated or 5% lanthanated (not that easy to get) not Thoriated.
     
    minimutly and Ianb like this.
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