T joint issue

[teign2nz]

Hi
To start with I'm not a welder. More gluing with metal but I'm working on it.
Below is a link to an issue I have......

http://www.doityourself.com/forum/welding-metalworking/456680-help-stick-welding-t-joints.html

I'm using a little 80A inverter with 5mm steel angle iron to practice on. But the other day I had the same issue with better kit.

There appears to be no answer. So here is a guess.....

An arc will always go to one place only at a time. If in the case of a T joint enough heat is generated then both parts will fuse together. Due to low available amps the arc takes on side and only melts a little metal around it. Not enough to bridge the gap.

If this is the case is the answer to get a more powerful welder?
Hold the arc in one place until a good pool forms across the two metals then move very slowly?
If possible vertical weld so the new weld reinforces/ heats the lower weld?
Give up coz I'm talking bo..ocks?
Cheers

 

[pedrobedro]

Get some thinner rods that will go into the join. Grind or chisel all your old weld out and start again don't try to work over the top of it or you will just end up with a bigger lump joined to nothing.

 

[GrahamGKD]

Hi,
I’m no particular expert but I have done quite a bit of MMA (stick) welding on various home projects. 80A does sound a bit on the low side for 5mm but what rods are you using – there should be a spec for the range of current, whether they are suitable for AC, DC etc. on the box?

Not sure if you have seen it but there is a great arc welding tutorial here.

You should be able to see where the arc is going while you are welding? I’m guessing you are striking the arc to the piece that has the welding return (earth) connected to it and never bridging to the other part? Watch the arc and manipulate the rod until is it striking to both pieces and then carry on with the weld while watching the arc and making adjustments if it is trending one way or the other. With the problem you mention I wonder whether you are allowing the arc to get too long (not holding the end of rod close enough to the work).

If this is the case is the answer to get a more powerful welder?
You say you tried a better machine and had the same problem?

Hold the arc in one place until a good pool forms across the two metals then move very slowly?
In my experience if you move too slowly you tend to get flux inclusion in the weld – it depends how slow you mean really? The normal practice to build up the weld is to do multiple passes.

If possible vertical weld so the new weld reinforces/ heats the lower weld?
If you can’t sort it with normal downhand welding then I think you will only make things more complicated by going vertical?

Give up coz I'm talking bo..ocks?
Never give up mate – you can crack this!!

 

[penfold]

I'd have thought your (lack of)penetration problems will be made worse with thinner rods, not better. Thicker rods(assuming your machine can burn them), more heat, more penetration. 80A should be enough for 1/8" rods and a 5mm T-joint should be achievable. Can you arrange the joint so that the planes being joined form a V rather than an L? Making the 'downhand' more 'downhand' can help in marginal cases IYSWIM.

 

[PTvor]

An 80A inverter should be fine with 2.5mm mild steel rods although you might find the duty cycle a bit of a problem. 2.4mm =3/32". I don't think you'll get away with a 3.2mm (1/8th) rod myself.

One thing you may be able to do is turn the work so that you are making the weld in the angle of a V rather than an L and let gravity help rather than hinder.

The other thing to remember with most 6013s is that you can touch weld, that is weld feeling the flux in light contact with the metal and let the burn back of the core wire into the flux coat supply the gap.

It helps a lot of you've cleaned up the surface you are trying to weld so it's bright, and not relying on the flux to deal with rust and millscale.

It would be far easier with a 1/8th rod and a machine which supplied enough current to run it properly, which with my inverter is about 110A according to the dial.

Apart from that it's just practice.

 

[teign2nz]

Hi
Been busy so sorry for not getting back.
Many thanks for the replies. Useful info there.
Just had a moment to play again.
Was using 2.5mm rods.
I picked up some 2mm.
What a difference. Won't win any awards but there was real welding there...Well to my eyes anyway.
I think tomorrow time willing I'll try the let gravity work for you idea with the 2.5mm.
cheers again.
Ian

 

[pedrobedro]

Getting into the join makes the difference, gravity will not help melt the metal only the arc can do that but the V will give you better access than the L set up. As above let the rod rest in the gap and draw it towards you, it will feel like the hand set is sinking into the metal gradually under it's own weight when you get it something like

 

[PTvor]

If you haven't been doing it, grind the surfaces of the steel where you are going to make the weld back to bright steel with an angle grinder, and grind the spot where you are going to put the earth clamp so that it's bright and you have a good earth contact.