neatening mig welds with tig

[mark1]

hi all new on here, so sorry if wrong section.

bascially am fitting a muiltypoint roll cage in in my rally car, started to mig weld it up as me mig weldings pretty good, do alot of seam welding etc, but becoz of the roll cage postions etc the mig weldings looks quite messy...

soo couple of things can i get a tig and basicali go over the mig weld and melt it down abit to smooth it down?

i have neva tig welded befor so i will practis on some other bits first, how hard is tig welding?

i also need to buy a tig what would you gues reccomend? only needs to be dc, max thickness will be doing is about 4mm mild steel.

cheers mark

 

[Wozzaaah]

If the welds are 'messy' are you sure they're structurally sound?
You can run over them with a tig welder but with the cost of buying the kit, the amount of gas you'd use and the time it would take would it be worth it just for the appearance?
It's unlikely smoothing them off would have much (if any) effect on their integrity.
Regarding machine choice, DC inverter, about 140-160 amps and HF start would be about right so what sort of money are you planning on spending?

 

[mark1]

yes defo stuctuali sound, my friends is a welding inspector on oil rigs etc, and hes had a look at it said its fine, just abit messy, will upload a picture.

am looking to buy a tig welder anyways as i do alot of welding and tig will be really help full i have only done a few bits on my cage anyways so will finish the rest all completely with the tig,i dont myn speing upro aroung 600incuding vat... or am i been tight hmm lol. already have account for gas so it doset bother me, like say will be using it alot once i have it and picked it up etc,

cheers

 

[mark1]

 

[mark1]

thats the worst 2, main issuse i have is just getting the torch in there.

 

[Wozzaaah]

I was expecting to see a lot worse than that, they're not too bad at all to be honest.
If they're the worst ones then I wouldn't bother with going over them but if you've got the gear, gas and time then I suppose there's no reason why not.
£600 will get you a decent machine, something like this one from Weldequip's shop or something from R tech.

 

[hotrodder]

soo couple of things can i get a tig and basicali go over the mig weld and melt it down abit to smooth it down?

i have neva tig welded befor so i will practis on some other bits first, how hard is tig welding?

Doesn't really work like that. To remelt and 'wet out' the existing weld you need throw quite a bit of heat at it which can cause far more problems. To neaten things up with TIG the existing welds would really need to be ground back some first and filler used when rewelding.

Some people pick up TIG quite quickly, many find it very difficult... if limited access possitional welding is your issue with MIG expect things to be about eleventy million times worse with TIG

 

[mark1]

cheers mate,i do alot of motorsport prep work usual seam welding, and just welding the cages in as usual come ready done so a case of welding mounts in and the cages legs or welding mounts in onli for bolt in cags but i have gone silly with my cage and bought the wrc spec on.

yes defo need a tig, i have been looking at a few main things am unsure of is what power i need, so will 160 be ok?

what brands are good? and whats best to avoid?

thanks

 

[Engineer]

Sadly TIG welding isnt as easy as simply buying a machine and starting work! Not sure if you intend to use the car you have done cage welding on in serious competition, but if you do, and the cage is T45 rather than gas pipe, its not that great an idea to MIG weld it.

 

[hotrodder]

Yep 160A will cover your 4mm steel max thickness needs, personally i don't see the point in a DC only TIG if your world is motorsport (a 200A AC/DC machine would cover pretty much everything including aluminium casting repair) but if you'll never want/need to weld aluminium...
£600 budget is quite a ways short for top brand name kit, Wozzaaah posted links to two safe choices.

 

[mark1]

Doesn't really work like that. To remelt and 'wet out' the existing weld you need throw quite a bit of heat at it which can cause far more problems. To neaten things up with TIG the existing welds would really need to be ground back some first and filler used when rewelding.

Some people pick up TIG quite quickly, many find it very difficult... if limited access possitional welding is your issue with MIG expect things to be about eleventy million times worse with TIG

cheers mate, main issue if the with of the mig torch and the angle etc to get it in there, when speaking to a few mate, tht work in motorsport aswell they say its so much easyer to tig weld them, ombs will have couple months practic befor i touch my cage etc,

Sadly TIG welding isnt as easy as simply buying a machine and starting work! Not sure if you intend to use the car you have done cage welding on in serious competition, but if you do, and the cage is T45 rather than gas pipe, its not that great an idea to MIG weld it.

yer i realise its not tht simple, like above will practic for couple months 1st, yer the cars for stage rally, but its CDS steel not T45.

Yep 160A will cover your 4mm steel max thickness needs, personally i don't see the point in a DC only TIG if your world is motorsport (a 200A AC/DC machine would cover pretty much everything including aluminium casting repair) but if you'll never want/need to weld aluminium...
£600 budget is quite a ways short for top brand name kit, Wozzaaah posted links to two safe choices.

reason been i have just got my own bodyshop and we do alot of rally prep, fitting hi spec engines, brake, Suspension upgrades etc,... so i have just laid out 1000's on tools compressors, mig welder plamsma cutters ramps etc etc, so just after a cheap ish tig to last me a year whislt i learn it proper then buy a good AC/DC one with budget off around 2000.


also whats the hardest metals to tig? ali, stainlessm mild steel etc?

 

[hotrodder]

Torch angle of attack etc applies to TIG as well and is compounded by the fact the filler wire is fed seperately which also means you don't have a spare hand for support after you've contorted yourself to reach the weld. Granted TIG torches can be smaller* but you won't get a nice small torch with a cheap machine.

Aluminium is generally considered harder to weld, personally i'd say it's just different. Mild steel is certainly the most forgiving, stainless is very similar to weld (puddle behaviour is a lit different) but less forgiving of excessive heat input, pulling the wire out of the gas shield etc

*they're typically supplied with a wp17 size, over twice the size of a wp9 which is limited amperage wise as it's air/gas cooled (can fix that by going water cooled but more £££ for a torch and obviously need a water cooler too). Flex headed versions of any/all of the above can make life easier but typically will need to be bought as an extra

 

[Engineer]

If you want something cheap and cheerful to get started look at a DC scratch start TIG/MMA set. If you are welding reasonably thin material (up to 120A) then you can get hold of a quite compact air cooled torch, which will make things easier.

I personally find aluminium easiest to TIG weld, but main problem you will have on using TIG to prep shells etc, is that it doesnt like dirty material, and unless its all very clean or ideally new, getting to grips with MIG properly is going to be an awful lot faster, and produce reasonable results.

 

[langy]

I weld a lot of cages and a 160HF would do the job nicely, Definitly don't bother with a scratch start as you will be dissapointed, a 200 AC/DC HF will be even better, also get a foot pedal as it will give you much better control.

As Hotrodder said TIG can be picked up very quickly or can take ages to master, it depends on the person. When i learn't the guy teaching me said it shouldn't take me long to pickup as i knew gas welding, I reckon i was putting down good quality welds in under an hour.