Mig welding : 100% confidence : 0% know how

[giraffeinbath]

Because I seem intent on doing things the hard way I was going to have a go at butt mig welding a plate into my cargo floor + wheel arch so that I don't end up with a big raised unsightly patch on the inner and outer sides of the holes that need repairing.

Question is, whats the best way to tidy and flatten the weld once complete?

Would this be the correct use of flapper discs? i.e. to flatten the raised weld without wearing thin the surrounding metal?

The closer I can get to it looking like there is no patch at all the happier I'll be.

 

[Joval]

Haven't done a heap of welding myself but yeah, flap disc to hide the weld - but watch the heat, those things heat the metal very quickly.

 

[giraffeinbath]

....but watch the heat, those things heat the metal very quickly.

Righto. Anyone know what is the best grade of flapper wheel to grind back the weld?

 

[Alzy]

I have been using ones from homebase!! They come in a pack of 5 i think.. They are costing me a fortune but do the job brilliantlyand you have to buy a rubber pad to use them on the grinder!! I asked this a while back but can`t seem to find the post!! I think J+M mentioned something!!

HTH

 

[Joval]

I get them cheap on ebay - 120 and 80 grit... I think..

 

[giraffeinbath]

Cool, cheers.

Time to start welding up an old washing machine for practice before I start cutting up the van

 

[Joval]

More than likely galvanized, watch the poisonous fumes or even better get some clean sheet steel to practice on.

 

[Justin & Muttley]

More than likely galvanized, watch the poisonous fumes or even better get some clean sheet steel to practice on.

WHS^^

You'd be better off making a trip to your local friendly scrapyard - an old door or wing would be much more suitable for practice!
I get my flap-wheels from the local boot sale - but eBay is also a good alternative, I find them easier to control than grinding discs and you do get a much flatter finish (although you do need to watch the heat so don't press too hard and keep it moving!).

If all else fails you should be able to get some sheet steel from whoever supplies your local body shop, ask around - those guys are usually really helpful...

Good luck with it...

 

[giraffeinbath]

More than likely galvanized, watch the poisonous fumes or even better get some clean sheet steel to practice on.

Shame I didn't read that before I started, still breathing though so it's all good

Fresh Question:
If you are butt welding two pieces of steel, is it best to have them so that the edges are touching, or is it better to have a small gap between them for the weld to penetrate between the two edges easier?

 

[Justin & Muttley]

More than likely galvanized, watch the poisonous fumes or even better get some clean sheet steel to practice on.

Shame I didn't read that before I started, still breathing though so it's all good

Fresh Question:
If you are butt welding two pieces of steel, is it best to have them so that the edges are touching, or is it better to have a small gap between them for the weld to penetrate between the two edges easier?

Best to have them butted together, but with the edges ground to an angle so you're laying the weld into the resulting 'V' - I always find that if you have a gap you're more likely to blow holes in it!!

 

[Joval]

I find I get less distortion with a very small gap, but yeah it's very hard to do it without blowing holes.

 

[giraffeinbath]

I'm aiming to try and complete the welds so that there is a fairly smooth raised weld on the opposite side of the join as opposed to being able to still see the edges from the reverse side.

Is this correct?

Is there anything wrong with doing one side and then welding the other if the weld hasn't penetrated in the way it should?

 

[Joval]

Every thing you need to know can be found here -

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

I bought my gear and got started with the great help from people on the forum there.

 

[giraffeinbath]

Every thing you need to know can be found here -

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

I bought my gear and got started with the great help from people on the forum there.

Just the job

 

[Justin & Muttley]

I'm aiming to try and complete the welds so that there is a fairly smooth raised weld on the opposite side of the join as opposed to being able to still see the edges from the reverse side.

Is this correct?

Is there anything wrong with doing one side and then welding the other if the weld hasn't penetrated in the way it should?

Nothing wrong with this at all - I had to do the same today on a piece I was fabricating! Penetration is the key, if you've got solid metal from one side to the other then it's right!

Practice on some scraps then cut through them to check your penetration, if all looks well then go for it...

 

[Guest]

thinner metal shouldnt need much of a gap if any at all, you will naturally get a small gap anyway, you really only space and angle the edges if your butt welding thick steel for better penetration. The weld on the opposite side to your weld shouldnt be as thick as the facing side for good solid weld.

http://www.mig-welding.co.uk is an excellent reference (some really good tutorials) and check out the forums for others first trys.