# Arc welding 3mm mild steel ?



## flanajb (21 Aug 2011)

I need to make a frame out of 75mm * 50mm * 3mm mild steel box section. The frame is for my planned cnc that I am going to make.

I have never welded before and was hoping there might be a forumite on here who can provide some guidance.

I am planning on arc welding the joints (I will have to learn how to weld first.)

1. Can I arc weld 3mm mild steel or is it too thin ?

2. If I can, what rods should I use ?


Thanks


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## Peter T (21 Aug 2011)

If you don't know how to weld, you might want to consider MIG rather than MMA.

It's much easier to get the hang of and decent equipment, that will run off a 13 amp supply, is relatively inexpensive.

Good luck,


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## flanajb (21 Aug 2011)

Peter T":2swivc1y said:


> If you don't know how to weld, you might want to consider MIG rather than MMA.
> 
> It's much easier to get the hang of and decent equipment, that will run off a 13 amp supply, is relatively inexpensive.
> 
> Good luck,


Thanks Peter, I will have a look into MIG instead.


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## No skills (21 Aug 2011)

Defo look into mig welding, its pretty easy with some practice and a little advice here and there.

If you plan on doing a bit of welding in the future for other projects then seriously look at getting a mig with a regulator that you can use with large bottles of gas rather than the tiny 300g (or there abouts) disposable efforts, you can easily spend a lot of money on disposable bottles making them a poor option compared to a rented larger bottle.

You could use 0.8 gassless mig wire to save all of that but the weld sometimes isnt as neat (imo).

Get some spare material to practice on, both to practice the welding and also to practice making 90 degree joints - you will be supprised how much a small spot weld can pull a set up joint out of square if it isnt clamped down properly.

hth


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## flanajb (21 Aug 2011)

No skills":x28oydm1 said:


> Defo look into mig welding, its pretty easy with some practice and a little advice here and there.
> 
> If you plan on doing a bit of welding in the future for other projects then seriously look at getting a mig with a regulator that you can use with large bottles of gas rather than the tiny 300g (or there abouts) disposable efforts, you can easily spend a lot of money on disposable bottles making them a poor option compared to a rented larger bottle.
> 
> ...


Thanks for the tips. If I want to be able to weld 3mm, what spec MIG welder would you recommend ?


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## DaveyP (21 Aug 2011)

> You could use 0.8 gassless mig wire to save all of that but the weld sometimes isnt as neat (imo).



+1 on that.

Unless its a good mig that has a high quality feed then arc is a lot simpler and cheaper, but its a learning curve.. the good news is that once the art is learnt then its never forgotten it just that the first part is steep.

A good mask, a magnetic square or two is important and loads and loads of practice, start flat then when thats mastered progress to vertical and then for the experts is overhead (but I've never got as good as that).. getting the arc started is akin to striking a match, easy to say but


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## No skills (21 Aug 2011)

[/quote]Thanks for the tips. If I want to be able to weld 3mm, what spec MIG welder would you recommend ?[/quote]

As mentioned arc is a bit cheaper if this is a one off, if not then buy the best you can afford - absolute minimum 90-100 amp or you will be very limited on how thick you can weld (go 150 if you can). Havent brought a mig for 15 years so I might be a bit rusty  some used to come with a nasty plastic liner that the wire runs through, avoid this like the plague!

The more expensive machines will have better adjustment for power level and finer control of wire speed.

again hth


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## t8hants (21 Aug 2011)

Not that I would want to discourage anybody from learning to weld as I am a fabricator by trade, but if it is an important project why not get a professional to do it for you, and you can learn on something that is possibly slightly less critical. You can buy a lot of proffesional weld time for the cost of basic DIY equipment. 

If you want to take it up as a new skill then that is a different matter. I would avoid the gasless MIG sets myself as they are only really aimed at the DIY car repairer. You have not mentioned a budget for your equipment, if going new get the best you can afford in a MIG set with good wire feed control, and a Bowden cable wire feed liner. Inverter arc sets are brilliant, if second hand older is usually better built. You will need to learn how the material distorts with the heat, the correct settings for the thickness, etc, etc. I haven't looked, but I expect there is a load of You Tube clips to watch. Once you have cracked the black art you will wonder how you got by without it. 

Gareth


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## No skills (21 Aug 2011)

Also.. #-o you will want c02 or a c02 and argon mix (know as argo shield at BOC) for welding mild steel.


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## jasonB (22 Aug 2011)

Hitachimad who sometimes frequents this site has his on welding forum, plenty of info there regarding choice of machine and size vs thickness

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

J


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## chunkolini (22 Aug 2011)

I do a lot of welding myself, definitely go for Mig, get at least a 130 amp welder, Clarke make some great hobby welders, mine lasted 6 years of serious abuse. Dont buy an SIP hobby welder or some chinese junkland Ebay bargain.
Well worth doing a night class' or getting a mate who knows to to give you a few lessons, I taught myself from scratch and almost went mad, then it clicked.
The best forum on the web is http://www.mig-welding.co.uk/forum/index.php as mentioned above, a bit like here, lots of knowledge and no big heads or bullies.

It is a skill well worth picking up, but it can wreck your life.
I did my basic course thinking 'try a bit of sculpturing', then 6 years back I walked out of a 20 year career to work full time as an artist.
You will also go mad. Spending hours wearing a bucket on your head staring at a tiny spark is not good for the sanity.
Anywhere in industry the welders are always the maddest ones.

If you are planning on making a CNC router you are obviously of a technical bent and will find welding as said already will become an essential.

Good luck with it, if you want to pick the remains of my brains feel free to email me via my website, www.artinsteel.co.uk

Chunko'.


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## monkeybiter (22 Aug 2011)

Where's Mr. Brock when you need him?


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## t8hants (22 Aug 2011)

Just wait till you get your first dose of arc-eye!!

_Arc-eye burning like fire,
Arc-eye, when I close there's pain.
Oh will my eyes that hurt so badly ever see again?
Arc-eye._ :shock: 

Gareth


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## monkeybiter (23 Aug 2011)

Or zinc-ague, after welding galvanised steel, 24hrs of feeling rubbish.

EDIT: That's strange, I thought 'rubbish' would be allowed


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