TIG vs MIG Welding

  1. malcolm

    malcolm Administrator Staff Member

    Posts: 8,264
    Bedford UK
    I sold a car during the summer and am planning to spend some of the money on a new toy.

    I'm generally happy with my old and rusty Clarke 155T MIG, but I'm only neat down to 1mm and don't enjoy welding anything thinner than that. I'm about to start welding on the first of 2 or 3 Renaults which have approx 0.7mm floor pans so it's about time I sorted myself out with something. Most of all I want perfect neat welds on thin stuff.

    I've seen how neat TIG welds are on thin metal, but have never used one. What sort of TIG would I need to make perfectly neat welds on metal as thin as 0.5mm? Also are there any disadvantages of using TIG for repairing my Renaults. I guess working speed will be slightly slower, but is there anything I'm missing? Is welding upside down possible with a TIG?

    A snowboarder can pick up skiing quite quickly. Is it the same going from MIG to TIG? I'm not planning on having lessons, but would pick your brains on the forum.

    And if a TIG is the way forward, what spec? In particular is a foot pedal useful when I'll not be sitting at a bench. Should I be looking at any particular wave shape for ease of use? Presumably HF start would be a basic requirement. Anything else?

    Finally AC vs DC. The much cited difference is the ability to weld aluminium on AC. Does AC have any other advantages?

    So many questions. I'm interested in ideas so I don't buy myself a pile of junk. Perhaps I'm barking up the wrong tree and want a fancy MIG. Budget is going to be around £1,000.
     
  2. Hitch

    Hitch Moderator Staff Member

    Posts: 10,268
    Somerset
    I wouldnt have thought tig will be great for cars. It takes a lot of practice to be able to tig in awkward positions like overhead.
    Not to mention the metal will need to be very clean....
    Do you have a very steady hand Malc? You will need one!

    As for working speed, it will be considerably slower than Mig
     
  3. malcolm

    malcolm Administrator Staff Member

    Posts: 8,264
    Bedford UK
    Clean metal I can do. MIGs can only make decorative welds on dirty metal so I try for shiny metal before welding. A slower working speed I could probably cope with - welding would give me something to do while the metal is cooling to prevent distortion. A steady hand might be more of an issue, but I suppose I could cut down on the coffee if it would get me a better weld.

    What are the problems with overhead TIG welding that MIG doesn't have?
     
  4. Hitch

    Hitch Moderator Staff Member

    Posts: 10,268
    Somerset
    You will have the advantage of no sparks to get you, but you will need the steady hand to hold the torch and the other the wire. Avoiding stubbing the tungsten gets harder when your not in a comfortable position.

    Thats the problems i have with it, everyones different i suppose.
     
  5. malcolm

    malcolm Administrator Staff Member

    Posts: 8,264
    Bedford UK
    That sounds a lot like grounding the tip on a MIG. Everything goes wrong when that happens - fuses blow, wire gets stuck up etc. And I should imagine the tip needs to be a little closer to the workpiece with TIG as the arc isn't assisted by the mig wire.

    How about welding vertical with TIG? I''m puting together a jig that should prevent me from ever needing to weld underneath the car again. I don't like metal blobs in my ears.

    Otherwise would sticking with MIG be sensible? Are there any MIG features that would help on the thin stuff?
     
  6. I've never used a TIG in my life but I've been doing a lot of thinking about it and here's what I've come up with so in my opinion ... You'll have at least the same problems with out of position TIG as you do with O/A due to using a filler rod. The use of a foot pedal while working on a car would be difficult at best I should think as usually welding a car (as you know) you're crouching or just plain sprawled all over the place, but, if you have a pedal for doing bench work all the better !
    As for MIG to TIG, as I'm told by Terry, a guy I know who's been in the welding game for more years than I've lived, there's no comparison, it's totally different ! going from TIG to MIG on the other hand is a no brainer. O/A to TIG, he says, helps A LOT.
    HTH
    Jim
     
  7. weldequip Member

    Posts: 5,071
    England
    I agree with the other guys, TIG is THE process for bench work but for a lot of typical car repairs it's just not practical. Laid on your back trying to weld under a wheel arch is hard enough with MIG, never mind trying to position the TIG torch AND then trying to get a filler rod in!
    You know what you need Malcolm, a PORTAMIG machine with 20 Amps bottom end performance!!
    weldequip
     
  8. malcolm

    malcolm Administrator Staff Member

    Posts: 8,264
    Bedford UK
    Sounds like a TIG isn't a good option for what I want to do - the Renaults are quite small but I'd never fit a whole one on the bench, and it sounds like I might be neater with a MIG at funny angles. I'd still like to play with TIG at some point, but for the Renaults I'm probably looking at a MIG.

    The Portamig does look like a lovely welder - I'll send you a message weldequip.

    Before I plunge into anything - don't they do MIGs with a square wave current to help with arc stability at low power and make TIG like welds? Would one of those be out of my budget?
     
  9. weldequip Member

    Posts: 5,071
    England
    Square Wave output is on AC so applies to TIGS rarther than DC MIGs.
    There are some really sophisticated sets on the market now that can produce spatter free, TIG like welds but they are serious money and when they go wrong... scratch head & send back to the manufacturer (MORE serious money!).
    weldequip
     
  10. Bigjoe Here,there and everywhere!

    Hi Malcolm,
    TIG really is the top of the pecision welding stakes but unless its fresh new metal it can be a bitch and welding car bodywork can be awkward although you can fuse new metal into a panel without introducing filler wire which makes the metal easier to work,and you can get remote torches for most good Tig machines now which remove the need for a foot pedal.

    You buy yourself a synergic mig machine malcolm, :cool: :D :D
     
  11. weldequip Member

    Posts: 5,071
    England
    Synergic MIGs are great but ENTRY level is £800 for a semi-synergic (which are poor quality) & you are looking at least £1500+ for a decent true synergic.
     
  12. migmag

    migmag Member

    Posts: 646
    North east
    Aint the higher end AC/DC tigs capable of plasma cutting????

    How mutch eisier would a plasma cutter make resto work plus you could weld ally ect if the time arose.......
     
  13. weldequip Member

    Posts: 5,071
    England
    Not to my knowledge. There are one or two 'Multi-Systems' on the market but most AC/DC TIGS are just that.
    weldequip
     
  14. migmag

    migmag Member

    Posts: 646
    North east
  15. Nial Member

    Posts: 45
    Edinburgh
  16. I had a look through that ages ago when I was looking for tips on replacing rear quarter panels, I didn't learn much but he's made a bloody good job of the car !
    TIG I think, would be ideal for doing the rear quarters on a mini, the but joint where the replacement panel connects to the rear pillar and the door pillar is in a position where TIGing would be more than feasable and you could run a REALLY nice clean bead there with the minimal of clean up after. I however did mine with O/A and linished afterwards and slapped a bit of filler on (not much at all) I have to do the other rear quarter at some point (very soon) so if anyone wants to lend me a TIG .... :) This time however I'm going to lead load the finished result.
    The reason for lead loading this time ? First and foremost I've never tried it, so I'm just itching to have a go (breathing mask at the ready) secondly, the filler on the other side has just started to swell ever so slightly as filler does eventually and thirdly, you get loads of bits and pieces in a lead loading kit :)
     
  17. Nial Member

    Posts: 45
    Edinburgh

    Aye, the advantage of his rotisserie is that you should be able to get
    reasonable access to whatever you're welding.

    I've never used TIG, but surely welding in akward places is no worse than
    with gas where you need access with both hands? Or do you need much
    better control of the TIG tip than a gas nozzle?



    Nial.
     
  18. malcolm

    malcolm Administrator Staff Member

    Posts: 8,264
    Bedford UK
    The mini restoration looks fantastic - soda bath then tig welded together. Looks like a really detailed job.

    I'm keen to try out a TIG for car welding. Might pick up a cheapo on eBay and have a kick about. Can always sell it if I don't get on with it.
    It would be really handy to have the slope-down feature for thin metal. Seems a common feature on TIGs, but doesn't seem to appear on MIGs in my price range.
     
  19. Justme

    Justme Member

    Posts: 1,788
    Pwllheli Wales
    Whats "slope down" ?
    Justme
     
  20. Hitch

    Hitch Moderator Staff Member

    Posts: 10,268
    Somerset
    Down slope control will control the amps after you release the button on the torch, slowly reducing the amps so you dont end up with craters in the weld, or burn through on the edges.
     
Recent Posts