Natural undercut, Tig welding .

[Noods]

I've got a piece of 20mm X 20mm square box steel 3mm thick which I need to tig to another piece of flat 3mm steel.. I ask, is there a special technique for this or a change of settings? The 20mm bar has natural curved corners creating an undercut, which means it might be a challenge for me!
Added a pic below to try to show what I mean..

Many thanks
X

 

[eSCHEn]

Usually the wee valley from the round corner(s) makes it easier mate. It gives the gas somewhere to pool and because you have that metal side underneath it it stops blow through.

No special technique, get a nice close fit with clean steel and crack on

 

[Noods]

Usually the wee valley from the round corner(s) makes it easier mate. It gives the gas somewhere to pool and because you have that metal side underneath it it stops blow through.

No special technique, get a nice close fit with clean steel and crack on

Do you push the puddle under the undercut? Also do I approach with a 45 degree angle to my electrode?

 

[eSCHEn]

I can't tell from the picture but this is what I think you've got?

 

[Kent]

I see no great problem just crack on

 

[Noods]

I can't tell from the picture but this is what I think you've got?

View attachment 87081

Exact copy of what I've got mate ..

 

[eSCHEn]

Cool

So if the radius isn't too tight, just get your tungsten super duper sharp and get it pointed directly in the crevice. Proceed like a normal fillet.

If the radius precludes that, then aim at the bottom plate and wash the pool into the crevice with a little twist of the wrist. Sort of like this, red arrow is main direction and green is the wash motion:

Watch you don't cut in the toes with the edges of the arc, easy done (DAMHIK)

 

[Noods]

Cool

So if the radius isn't too tight, just get your tungsten super duper sharp and get it pointed directly in the crevice. Proceed like a normal fillet.

If the radius precludes that, then aim at the bottom plate and wash the pool into the crevice with a little twist of the wrist. Sort of like this, red arrow is main direction and green is the wash motion:
View attachment 87083

Watch you don't cut in the toes with the edges of the arc, easy done (DAMHIK)

Cut in the toes ?

 

[addjunkie]

Thats welder speak......if you make an **** and undercut the bottom piece you will weaken it.

And does it need to be tig. Can you not just bash on with a mig.

 

[Noods]

Thats welder speak......if you make an **** and undercut the bottom piece you will weaken it.

And does it need to be tig. Can you not just bash on with a mig.

Unfort I only have tig at present ..

 

[Richard.]

As above mate. Treat it like a fillet joint.

 

[Noods]

Not too bad... Would have liked it a little neater... X

 

[eSCHEn]

Like you say Noods, could be neater but there's nowt wrong with that mate.

What's if for BTW, or is it just a tester?

 

[Noods]

Like you say Noods, could be neater but there's nowt wrong with that mate.

What's if for BTW, or is it just a tester?

I still struggle with seeing sometimes and my hand shakes so I doubt I will ever be as neat as I'd wish to be... X

 

[eSCHEn]

I doubt I will ever be as neat as I'd wish to be...

You're not alone in that feeling mate

 

[Richard.]

It's a job well done IMO.

 

[Freddy0309]

I still struggle with seeing sometimes and my hand shakes so I doubt I will ever be as neat as I'd wish to be... X

I struggle sometimes with shakes and 2 things that help me is either a slide which is just literal a bit of scaffold tube on a stand that I slide my hand across and flexi head torch, a little tweak up means it feel comfier for me. I picked up some scaffold pole for free and use a scaffolding clamp to position close to the work piece or mount in the vice. Might be worth asking a local firm if they have a piece you could have

 

[Noods]

It's a job well done IMO.

Luv you Man..

Need the luv at the mo.... Just lost my little Sister to the dreaded C..
Lost without her.... X

 

[eSCHEn]

Loads of love from up here mate. Always

 

[Richard.]

Luv you Man..

Need the luv at the mo.... Just lost my little Sister to the dreaded C..
Lost without her.... X

Sorry to hear that N.
****** disease has got a lot to answer for.