Why not an inverter arc ?

[Dave M]

Hi guys, my first post... and for a change i thought i'd ask you all a question
I've used an Arc welder in my distant past and was ok'ish on 2-4 mm stuff.... more recently i've used a Mig, though i should add i mostly did basic tacking with it (rebar re-enforcing ) and only occaisionally did anything like proper welding..... but that was some years ago.
Anyhow, i will be in need of starting again so i can weld the sills and boot of my Disco.
Lots of good advice on here about what budget welder to get, but my question is even more basic than the norm.
I realise Arc is hard to do on thin steel, and Mig is the norm, mainly it seems because you can get the amps down low... if that is the reason , why can't an Inverter DC Arc welder do as good a job as a Mig? It would seem to my mind that as the amps can get so low , and as it's Dc it should surely do the same job.
Obviously an Inverter is cheaper to start with and requires no gas so running it would be cheaper...... I expect there is some very obvious reason why it's not done.... so please oh knowledgeable ones what is the reason?

Dave

 

[PTvor]

One obvious reason is that an arc rod is best suited to welding metal about it's own thickness to about twice its own thickness and there are no rods on the market thinner than 1.6mm. A lot of inverters go down to 5 or 10 amps, but that's not much use if the thinnest rods you can buy need 40 to 60 amps. The inverters go down that low, because it's easy to design in and useful for TIG.

1.6mm rods are a bit different in their action and seem to have a lot of flux in comparison to the amount of weld metal.

I imagine that there were attempts to make thinner arc rods but they weren't practical, and they certainly don't seem to be easily available now. 1.6mm rods are becoming harder to find because most of their market has been taken by MIG.

I think years ago there were people welding car bodies with arc, but it was a skilled business and when MIG became cheaper, it was obviously the way to go. O_A was more popular back in the day with people who were seriously interested in welding thin stuff.

As in most things, new techniques become available and cheaper and displace older methods. There was a time when woodworkers would have a stack of moulding planes which required skill to use and maintain. These days, routers do almost all that work.

 

[cumbriasteve]

In the days of the Hillman Minx, Anglia's, Cortina Mk1 etc the bodywork was a little thicker than it is now, even at that, attempts to make repairs with an arc machine was flaming hard work and involved heat sinks and a 'strike up' plate next to the patch.

It was possible and I put a few cills and outriggers on but it was very hard work, messy and certainly not consistent, I would certainly not like to return to those days.

 

[zzr1200]

As stated above minmium rod thickness is 1.6mm, plus years ago you could tack weld sills on and pass a mot, now the mot requires full welding of patches/repairs.

Hell, I can even remember when pop riveted patches where mot acceptable for some repairs.....mind you I am an old git....

 

[Lawnmowerboy]

hi, my advice was if you really wanted to get an arc buy one of those cheapo tig kits from ebay foor about £50 its the first tig we had in the workshop running off my little cemont blumaster 130!

 

[Dave M]

See, i said there would be an obvious reason as to why not
As i know nothing about Tig, and even less chance of learning to do it well enough.... i'll stick to Mig.
Shame , because all of the welding will be outside in the elements....

As soon as funds allow i'll hunt for a cheap Clarke set... the wife runs a bar ,so should be able to get my Co2 for free....... then you'll get all my pics from my first attempts to pull apart and hopefully re-educate me.
Thanks for the replies chaps.

Dave