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Thread: Please advise/help with my welding

  1. #1

    Please advise/help with my welding

    To make it short and sweet: I can't weld thin sheetmetal for *****.

    I keep blowing holes. I tried more wire feed, less, backing with a copper plate, a steel plate, nothing works.

    When I get to 2mm thick steel, no big issues (not nice, but holds).

    I fully intend to invite a welder friend for teaching, but in the meantime, some of the good people here could offer advice (or trash talk, I have thick skin).

    See damage below (yes it's a Beetle, I was not about to start on a 911...)

  2. #2
    I tried gas welding the thin metal in my car. I was so good at it that I decided to have it professionally restored.
    Seriously, wait for your pro friend. Practice on something that you can melt holes in without inducing tears.
    Bill S

  3. #3
    Quote Originally Posted by V1 Rotate View Post
    I was so good at it that I decided to have it professionally restored.
    Bill S
    Lol. I know the feeling. That is why I am doing it on a no name no date Beetle.

    Still I would like to know whether it is me, or is the machine not adjustable enough to avoid blowing holes everywhere.

  4. #4
    Serial old car rescuer Arne's Avatar
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    I'm going to guess (in my inexperience) that the arc is too hot. Looks like your welder only has limited power (amp/volts) settings. I've been learning to weld on my own VW project (Rabbit Pickup 16v), but the Eastwood MIG-135 I bought a couple months ago has stepless power settings, same as for the wire feed. I still have to be careful, but I can weld without blowing holes. At least most of the time.

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    - Arne
    Current - 2018 718 Cayman, Rhodium Silver, PDK

    Sold - 1972 911T coupe, Silver Metallic; 1984 911 Carrera coupe, Chiffon white; 1973 914 2.0, Saturn Yellow; 1984 944, Silver Metallic

  5. #5
    Senior Member uai's Avatar
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    I think it just comes down to 3 things.
    Practice, practice and practice. As well as preparation of the fit of the sheetmetal.
    Backing with copper really helps, but only helps if the copper is snug to the metal. A good (3M or similar brand) auto darkening welder helmet is also essential.
    Trying to weld a butt weld in 0.8 mm takes lots of practice. First try to use only points at 2.5 cm then grind them down then add points in between grind down again and then fill the 6-8 mm gaps in between.
    Another possibility is to have very little (2mm) overlap (see pic below). But it takes a proper beading machine to do them that small the pliers are not my cup of tea.
    What I think improved my welding skills (apart from practice) was the small grinder that allows to grind the welds without weakening the material around and generating very little heat.
    My absolutely favourite grinder is this one with the 20.000 RPM: I also have a couple of cheaper ones (all well known brands no china stuff - but the dotco kills them all)
    https://issuu.com/dvksagetechnik/doc...elschleifer4/2
    in conjunction with these discs
    https://www.pferd.com/de-de/produkte...cd/cd-38-z-36/
    It allows very accurate agressive and cool grinding - with good eye and hearing protection it made grinding (which is my most hated job besides sandblasting) nearly comfortable.

    Here the lower sill has an overlap of 2mm - weld grind weld grind - in the end it's one closed weld
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    Here is a patch that is held in place with little magnets - those magnets are fine, but do not try to weld near the magnet or with the magnet on the rear of the sheetmetal - it's impossible.
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    my next task is learning tig welding thin sheetmetal
    Last edited by uai; 02-02-2021 at 10:18 AM.

  6. #6
    Senior Member bob joyce's Avatar
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    do not try to run a bead. I know most videos show a guy running a continuous bead. Do not try to do that.... Instead start your weld and only moving 5mm or so and then let off the Triger. Then Triger again and run for 5mm....and so on and so on....... You will soon learn how much time in-between pausing. maybe a second or three or less. but you will learn to not let the heated metal fall out. Your job when welding 1mm metal is to keep the build up of heat to a minimum.....
    P,S. if your welding helmet is fairly new, has auto darkening et. it my also have a slot that will accept a 3 power magnification lens .... This realy helps a lot

  7. #7
    Senior Member
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    Few of my tips::
    - clean metal better, it should be clean enough to make a surgery. This is OFTEN the case, too much impurities
    - do not leave root gap when welding thin sheets, triple the time fitting panels before welding
    - then my opinion; your welding machine doesn’t look too good... I use Kemppi Minarcmig (and similar Esab, but prefer Kemppi), these are about million times better in every way than old machines (and fully automatic if wanted, just select materian and thickness) . And good automatic helmet.
    - short bursts with thin metal
    - practice, practice, practice...
    Last edited by Will 1967; 02-02-2021 at 10:32 AM.
    - Ville -

    1967 911 Slate Grey/red, fully restored + 66' "r-ish" hotrod project

  8. #8
    Senior Member
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    I don't see mention of wire size, on body sheetmetal I like to drop down to .023" wire, can you get .5mm dia? to me this is the only way to be able to weld the wire hot and not just stick to the metal or burn holes. you need to be welding with the sound of heavily frying bacon or meat, the only way to have that on the this stuff is to drop down in wire size. Keep the magnets and copper backing plates where you can.

    Best of luck!

  9. #9
    Senior Member
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    Quote Originally Posted by uai View Post
    What I think improved my welding skills (apart from practice) was the small grinder that allows to grind the welds without weakening the material around and generating very little heat.
    My absolutely favourite grinder is this one with the 20.000 RPM: I also have a couple of cheaper ones (all well known brands no china stuff - but the dotco kills them all)
    https://issuu.com/dvksagetechnik/doc...elschleifer4/2
    in conjunction with these discs
    https://www.pferd.com/de-de/produkte...cd/cd-38-z-36/
    THIS! Already wrote almost same things before seeing this reply But I forgot this important bit. I hardly ever use normal angle grinder to finish any welds, mostly this kind of sander with 3M 36 grit Rolocs (50 and 75mm), and small pneumatic grinders with 75mm cutting and grinding discs.
    - Ville -

    1967 911 Slate Grey/red, fully restored + 66' "r-ish" hotrod project

  10. #10
    Many thanks to all!
    Unless I missed a thread about welding in this forum, this is shaping up to be a reference for us amateurs.

    So far:
    -Clean more,
    -No beads, spaced welds
    -Thinner wire (I have 0.8mm)
    -Backing close as can be.
    -Grind flat often.
    -Get a better welder (I'll keep that for last...)

    Please keep it rolling! I'll keep on practicing, have enough scrap sheet.

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