sheet cutting with mig?

[hifly]

Hi, I have a small art type project that requires shapes to be cut in to thin sheet steel, neatness is not needed but i do need tight curves an a cut of around 3 to 5mm

I don't have a plasma cutter and its not worth spending the money on one just for this project

i tried cutting the shapes with my mig on high setting, the size and control were good but about 20% of the time it starts to build a weld up rather than blow through which is a pain.

does anyone think that modifying a mig nozzle to take a tig electrode will give me what i want or will i just be wasting my time and money?

if you think it may work which electrode would you suggest?

my mig is a clarke migpro 90.

Cheers
Vince

 

[Wedg1e]

Fundamental difference in operating process, not sure how it would work. What would probably 'work' after a fashion would be to replace the MIG tip (and wire) with a TIG tungsten electrode: the arc would strike and melt the metal but how you'd maintain the arc and how long the electrode would last with CO2/ Argon or straight CO2 are open to question... either way the 'cut' would be as raggy as a blown-off limb.

 

[Lawnmowerboy]

Imo you're on a hiding to nothing. It would be quite hard to get a tungsten to fit.

 

[hifly]

i have a lathe so i can mod a mig nozzle to hold a tig electrode,

i probably won't use any gas as i just want a cut, the mig does a fine job until it starts building up a weld, raggy is fine, in fact its better than a clean cut for this project.

any idea which electrode as there seems to be a lot of them, red, blue white etc and dia from 1mm to 4mm

thanks for the thoughts so far.

Vince

 

[pedrobedro]

A tig electrode without gas cover will disappear in no time if you can get it to work at all. Just do it and tell us what happened, if it melts your tip and swan neck we will know not to try it I can't see how anyone can offer advice on tungsten type for the use you are looking at, it's an unknown quantity.

 

[hotrodder]

I wouldn't worry about tungsten flavour, without gas i doubt you'll be able to maintain a stable arc for a couple of reasons, 1st to do with ionisation potentials (voltage needed to get an arc going) and secondly the tungsten needs something to protect it from burning up (oxidising). As said with argon/co2 mixes tungsten electrodes burn up pretty quickly because CO2 is dissociated by the heat and has an oxidising effect. Thirdly MIG uses the opposite polarity to TIG which means that even using pure argon the tungsten would melt as ~ 2/3 of the arcs heat occurs at the +ve electrode.

 

[hifly]

oh well never mind, i will just have to carry on with the mig, i only have co2.

another good idea ruined buy it not working.

but worth asking before i spent any money on it.

Cheers
Vince

 

[dickie bell]

i may be missing the point here but have you tried using a jigsaw and drill holes for any tight rad's ?

 

[hifly]

i may be missing the point here but have you tried using a jigsaw and drill holes for any tight rad's ?

the hole needed for a jigsaw blade will be to big, the cut to neat and i will not get the ragged style or size of slot i am looking for.

i need a plasma cutter but i don't have one.

you know what its like when you get a vision of how you want something to look and it is "art"

its ok i will use the mig and grind off anything it tries to weld.

Cheers
Vince

 

[chevy2]

You could cut sheet steel if you have an arc welder by turning up the amps way high and use the rod as a cutting lance?

Done it several times quite a few years back and boy it sure does leave a rough cut edge!

 

[langy]

the hole needed for a jigsaw blade will be to big, the cut to neat and i will not get the ragged style or size of slot i am looking for.

i need a plasma cutter but i don't have one.

you know what its like when you get a vision of how you want something to look and it is "art"

its ok i will use the mig and grind off anything it tries to weld.

Cheers
Vince

Surely its got to be neater than the way your currently doing it

 

[Jim_gsxr1000]

yeh for sure, can make a really good job with the jigsaw

 

[hifly]

yeh for sure, can make a really good job with the jigsaw

its just not what i am looking for, thanks anyway.

no stick welder.

i could reverse the polarity of my mig

so what is the difference between the colours of tig electrodes?

 

[Jim_gsxr1000]

Red= Throated slightly radio actictive good for steel
Grey= cerated good for steel
Gold= 1.5% latharanated also good for steel
white= Zicronated good for aluminium
Green= pure tungsten only as a last resort if you run out of everything else

 

[astro_al]

Thought about an oxy-propane setup? A million uses, not too expensive to get, can leave a nice ragged edge if required, will cut through anything or enable you to heat stuff up in order to manipulate it. A great asset.

Al.

 

[madkayaker]

Plus get a metal kettle and fresh brew in the garage

 

[hotrodder]

This thread shows what happens to the tungsten when there's a leak from assembling the torch back to front... http://www.mig-welding.co.uk/forum/showthread.php?t=27276&highlight=oxidising With straight CO2 or gasless i'd be suprised if an arc can be maintained for more than a couple of secs

 

[KemppiFrog]

Sounds like a plasma would be too neat compared to what you must be getting now.

£50s worth of stick welder would do it, can't you borrow one? Might even come in useful for other things

 

[ems]

It might be worth contacting a local blacksmith to see if they'll cut it for you.

 

[Daz1968]

On thin sheet I use a dremmel with various cutters dependant on what I am doing.