Welding Exhaust pipe?

  1. BudmannG Member

    Posts: 8
    I am new to welding and figured I would google about mig welding and found this site. Very nice write up on the tutorials!

    I have a 90 amp mig welder I just bought. I am trying to weld exhaust pipe together. It is really for my innercooler setup on my car. I have tried it on low settings and it don't seem to go through themetal as shown in the tutorials. I have tried it on high and I get blow through.

    Now with the gasless mig welder, how do I control the heat? Is it with the wire feed dial?

    This is my welder!

    90 AMP FLUX MIG WIRE WELDER

    NO GAS REQUIRED Specifically designed to use self-shielding flux-cored welding wire, eliminating any need for gas and regulators normal MIG welders require. Self regulating feed control Thermal protection with warning light Carry handle on lid Input: 115 volt, 15 amps, single phase Welding current (2 settings) 63 to 68 amps (low), 79 to 90 amps (high) Duty cycle: 10% @ 80 amps, 18% @ 60 amps Wire capacity: 0.035'' or 0.030''

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  2. weldequip Member

    Posts: 5,068
    England
    Hi,
    With Gas-Less MIG welders you tend to struggle welding very thin sheet as they don't burn as smooth as a standard Gas type MIG, having a stronger, more unstable arc which causes burn through on very thin metal.
    With your machine only having two settings you can't fine tune the arc & it's a case of all (high) or nothing (low). The minimum setting on low on your machine (63 amps) is also way too high - 30amps is typical on most machines which is half yours.
    BEST ADVICE - try & do overlap joints if at all possible ie. double the material thickness.
    weldequip
  3. BudmannG Member

    Posts: 8
    So does that mean I won't be able to weld the body panels on my car when I am ready to do that?
  4. weldequip Member

    Posts: 5,068
    England
    If you intend butt welding the existing panels then yes, I'm afraid you will struggle with burn-through. If you are fabricating new panels or patches yourself, use thicker steel & you will have a good chance.
    weldequip
  5. BudmannG Member

    Posts: 8
    That is the only reason I bought this thing. Dangit!

    Can someone point me in the direction of welder that will go down as far as I need it. My budget is very limited as of right now.
  6. weldequip Member

    Posts: 5,068
    England
    Don't let me put you off! I'm only talking from experience, but my experience is that the lower the better for a MIG to be able to successfully weld thin car panels - they are tissue paper thin nowadays!
    Have a go, but I think you will find that you are constantly blowing holes through the stuff & it may cost you more in the long run with botched panels.
    In the UK the Clarke range are good & they are also available in the States.
    weldequip
  7. Danger Member

    Bud, I have the Chicago Electric 151 220v series and set it up with shield gas. In everything I've read you simply can't do good sheet metal work with flux core wire as it runs too hot. .020 wire with sheilding gas is the recommended way to go from what I'm told (certainly not an expert...but done some reading). ;)
    Last edited: Jul 31, 2006
  8. BudmannG Member

    Posts: 8
    I will look into getting a different welder.

    I did go out and give another try, but with no avail. I got the same results. So I put my welder up for sale. And had a friend do the piping that I was working on. I am looking at getting another welder, Just wount be all to soon. I will take my time at buying one now and consider all the pros and cons with it. I have not picked one out yet, but I will. I want to do all the body work myself.

    Thanks guys,
    Bud
  9. malcolm

    malcolm Administrator Staff Member

    Posts: 8,168
    Bedford UK
    That sounds sensible. 25 - 30 amps is the normal minimum setting for a MIG welder.

    A 90 amp max welder would just about butt weld 2mm sheet, and a 130 amp should comfortabaly overlap weld 2mm sheet and butt weld 3mm.
  10. geetee Member

    Posts: 29
    Edinburgh
    I have a Clarke 100E from Machine Mart and I would say its pretty good with car bodywork.
    I taught myself to weld with this machine and then went on to save a "teabag" Cavalier with it.
    Also done things like stainless exhausts and brackets etc.... no problem.
    Think they cost about £150. Bargain.

    Just a small query, but can't you convert the "no-gas" welders to run with gas?
  11. fireicer

    fireicer Member

    Posts: 13
    this is an interesting and common thread

    Hi all

    i to a few years back was new to welding but i had got a head start with my engineering workshop practice which tought how to arc weld but hang on i purchased a mig welder.

    i have noticed on this thread that there seems some confusion to current settings i know i found that a headache when i started to mig weld and could never get it right and then i figured out why.

    i was using gassless wire now lets set the score strait. wire and gass is a very comfortable kind of welding especially when doing bodywork with 0.6mm wire and argo gas but if you do this outside when there is a breez then you have more chance of being bitten by a snowman. the wind blows your argo away from the weld meaning you dont get a cage of gas needed to sterile the weld. on comes the flux cored wire, you can weld in gale force winds with this stuff but you need to change your techneque yup learn to weld all over again.

    why? because the flux in the wire forms a plasticie coting ontop of the weld much like a laquer very shortly after it has been welded to the steel which means that it breaks or destroys the connection of the current circuit you need to form the arc. oops. techneque is needed to get this wire to weld well and this means you have to move the weld from side to side at a steady speed as if you were following a zig zaged line across your but weld. oh and you must leave a small gap betwen 0.5 and 1mm so that the weld can penetrait both weld equally and evenly replaicing the gap with the steel wire making a seemingles end of the weld you can flap wheel grind down and therfore become invisable. its all about time patients acuracy of your wrist and seting the wire speed correctly.

    sure we know we need about 25-40 amps to weld the cheese paper thin cars of today but 40 amps on some cars is to much and 25 amps for some is way to low. a 4 or 6 setting welder is what to look for note sometimes you need 50-60 amps even on tisue paper depending on what its fasend to as large metal items will steel the heat you need for the weld to pool or pudle.
    Do not try and weld back over a gasless weld it will just spatter and blob. if you want to weld over a gassless weld clean it get a twist knot wire brush and clean it real good then use break cleaner to wipe it free from greas and laquer then try it. i dont advise it though, just grind it back and start again. make sure you do not remove or thin out the tin plate of your car to thin as that will surely require less current and more current where it thicker meaning the weld will look very uneven and will leave it with a 20% weld efficincy. not good.

    by the way mig welding is very very poor welding results in comparison to tig and arc but they are adequate for what they are used for.

    you must practice practice practice with all forms of wire gas and gassless to realise that the movement of the rist is the key.

    rule of thumb let the welder do the work and when using gassless wire do not try weld ontop of a gassless weld untill you grind it clean and i mean clean.

    set the wire speed correctly and i do mean correctly.

    play with your current on a gash peice of the same steel your welding and look at the penetration it should go all the way through equally i.e. top and underside will apear to look very similar bottom side may seem slightly less on the weld but that is fine aim though to get the top weld to look like the weld apearing underneath equal hight as the top and your good to go.

    too much current it will blow holes but not moving at a constant rate will also blow holes you must keep it moving at the seteady rate that you found on a gash peice. if you still blow holes then make short widths i.e. 10mm stop anouther 10mm then stop and so on.

    Check out this page for further info and very cool pictures with vids of how to move your wrist in the welding of gassless wire in your mig. also shows howto set the current to the matirial and the wire speed.

    Oh did i forget to mention practice practice practice. its the only way it will be of quality is to practice:

    http://www.mig-welding.co.uk/tutorial.htm


    the guys tutorial works i tried it he is bang on read it learn it and boy you could charge once you get your practice. this is the most awsome page for mig welding i found on the net so you sure are in the right place.
  12. malcolm

    malcolm Administrator Staff Member

    Posts: 8,168
    Bedford UK
    Welcome fireicer. Reckon I'd agree with most of that (especially the bit about "this is the most awsome page for mig welding") :laughing:

    The comment about MIG giving very very poor results in comparison with the alternatives is interesting. The real benefits of MIG in industrial use are speed and ease of positional welding. Main disadvantage is excessive filler wire in some circumstances. Just wondering what the where the thought had come from.
  13. fireicer

    fireicer Member

    Posts: 13
    good question

    thank you for the plesent welcome malcolm.

    the thought on the poor results in comparison more comes from richard finch's welder's handbook (ISBN:1-55788-264-9):p and my experience which interestingly describes the weld process being hard to see, heavy smoke being produced and the highly bright arc which makes it very difficult to see the weld pool. in turn means that even when the weld looks good the actual is only 40% of what it should be because 80% of the weld is welded on one peice and not the other meaning the weld bead is only lapped over until the weld progresses. Of course this can be rectified as mentioned within the tutorial hehe by methods described

    the book goes on to describe it as being down to cold starts etc or untill the actuall arc heats up the matirial the weld looks good but has a very low actually welded on both pieces of material before it heats up.

    yes it is true the comparison of efficiency with mig welding is far greater in industry as to arc and tig, a mig can do the job in much less time and means you can weld more in shorter time but does not mean that the actual weld is better and yes the weld is good enough as it does pass the crash tests which it was tested, 9g's acording to form. It also is obvious that mig welding is far more flowing as you dont have to stop and change rods:welder: hence production is far more efficient again.

    mig welding as far more simple and much more productive than arc or tig and speeds up all forms of weld process. It Works and is certified as a good standard and a strong weld but is not the best you can get. well especially if your welding up a presure container such as a compressors reservior tank which requires a perfect seal. robotic welds in mig are far better today but we dont always have the room or money to have such high tech welding equipment lol and i am sure excelent well prcticed welding can come very close to that type of weld.

    i found mind you that it is always better to go for the bigest most powerfull mig you can afford:mad: because upgrading a small low current welder is not possible due to its construction and components but a more powerfull welder can be toned down to your needs:hug: . that has been my experience.

    The book is a very interesting read for types of welding, history and practical examples. still not as good as the live tutorials (link in my post above):laughing:
  14. charlie-b New Member

    i have got a clark mig 155 turbo i find it is perfect for body repair exhusts and chassis
  15. Tino

    Tino Member

    I don't agree with this. Firstly the mig if set and operated by a skilled welder in the right circumstances can produce better welds than mma or tig. Solid wire with gas will give a lower hydrogen value in the weld than even basic (lo-hydrogen, hydrogen controlled) mma electrodes. Each process has it's place and in it's place will be the best. Also the 500-600amp mig sets I use are far from simple to use.
  16. wallopadonkey

    wallopadonkey Expert Grinder !

    it aint perfect but its getting better

    on the subject of welding exhausts had to do a reair of a snapped exhaust not a clean break but i ground it and cleaned it , tacked it in 3 places then low power weave over the whole lot welded with a good hobby machine clarke 160tm, .6mm wire, power 1 max for spots and 1 min for seam with wire speed of 5 i was using argoshield light shielding gas and it was welded in the garden with a temporary wind break to help gas cover
    i think my welder goes down to 30 amps at 1 min with low wire speed
    hope this helps
    oh i painted it high temp matt black and passed mot no probs!
    dave
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  17. Tino

    Tino Member

    Another vote for Clark

    I to use a Clark mig for thin stuff at home, and like the others have found it very good with 0.6-0.8 wire and gas. Nice job Wallopadonkey.:welder:
  18. rustyreks New Member

    Posts: 1
    New Zealand
    There is another option that hasnt been mentioned you can try your welder at the lowest setting and pack some copper sheet behind the area you are welding this will take the heat away in the old days they used dampened asbestos as another option i have welded up really thin metal that kept blowing out on the lowest settings on my mig it has gas but without the copper kept blowing out i even welded up headlight casings that people said could nt be done with a mig welder usually tig is the best for really thin metal got that tip from a very good repair man i know thats an old trick of the trade certainly worth a try rustyreks
  19. KTMMICK

    KTMMICK Member

    by the way mig welding is very very poor welding results in comparison to tig and arc but they are adequate for what they are used for.
    I think you are very mis-informed somehow..........yes Tig is very good, but slow in comparison as is Arc. Any weld in the hands of a competent trained person will yield excellent results.
  20. runnach Banned

    Posts: 1,827
    Edinburgh
    I realise not everyone has this option, but for me oxy-acetylene is by far the best method for welding old motors, floors panels ect.

    Regarding exhaust repairs, last week repaired Merc SLK exhaust, usual symptoms, poor welding and corrosion allowed for exhaust to wander a wee bit. I've added pics, SLK exhaust is the one with two cats, saved me around grand doing repair :o

    About month ago exhaust on Shitroen fell off:laughing: pipe at cat (exhaust gas in >>) parted due to corrosion, cat going out>>>, I repaired this 2 year ago due to blowing because of corrosion around weld. Extra 2 years is good going, I asked for cat to be returned when I picked up car from exhaust fitters, I repaired this evening, pic with red-ish paint around weld is 2 year old repair. Close up (no paint) is tonights repair.

    If I had decided to repair using MIG, I would have toiled for sure, my preference for O&A on these type of occasions made repairs far easier, one can dance the flame around, giving welder far more control on heat input, where with MIG, it's a quick burst and pray you don't burn through.

    I'm actually not an O&A fan, but it certainly has its uses!!!

    Cheers............
    • Citroen 2 yo repair.JPG
    • Citroen Cat broken.JPG
    • Citroen cat repaired..JPG
    • Citroen new repair..JPG
    • SLK broken brk.JPG
    • SLK corroded brk.JPG
    • SLK exhaust.JPG
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