[weldnoob]

Hello to all... I am TIG beginner and I can make decent joint with coupons either fillet or butt... In all cases there is no gap between plates,a and it is not problem for me...
But, I cannot repair any crack where there is a gap between edges of the crack... When I try to start on the begining of the crack, I cannot brridge the crack with filler metal. Simply "keyhole" technique doe not work. It happens that the edges melt and the gap is becoming wider, instead to be joined...
I am just guessing now, what would be the solution:
- Either to butter the edges lengthwise, with low amperage and small diameter of filler rod and get the gap to almost zero?
- Or start to butter the edge of the beginning of the crack, spot by spot along the crack...
- Or to put some "patch", cut from some Alu. plate and place it over the crack to cover the gap, and make some kind of lap joint with patch over cracked part?

Do you have some practical advice?

[anthonyfawley]

More filler should do the trick. you could also push the filler in as you go. Try going a little slower.
Hope this helps
Anthony

[weldnoob]

More filler should do the trick. you could also push the filler in as you go. Try going a little slower.
Hope this helps
Anthony

Thanks, I will make some cracks in several plates and practice like you say (starting pool before the crack, slower travel speed, lower amperage, pushing rod in pool...)...

[sschefer]

More filler should do the trick. you could also push the filler in as you go. Try going a little slower.
Hope this helps
Anthony

Thanks, I will make some cracks in several plates and practice like you say (starting pool before the crack, slower travel speed, lower amperage, pushing rod in pool...)...

Cracks are full of jagged edges that melt back quickly and appear to make the crack open up. You need to grind out the crack first and then clean it before you can weld it successfully. That seems to violate the tight fitup rule but if you use the lay rod technique and make two passes you'll be fine.

Depending on the crack I use a die grinder or a 4-1/2" cut-off wheel the get about 1/2 way into the depth of the crack and then bevel the sides if I can.

[weldnoob]

That seems to violate the tight fitup rule but if you use the lay rod technique and make two passes you'll be fine.

Sorry to say, I was unabel to do any successfull lay-wire bead so far.
Simply, the filler rod was being burnt before melted and being sucked in the pool... Is there any advice how to apply lay-wire at alu?

[sschefer]

That seems to violate the tight fitup rule but if you use the lay rod technique and make two passes you'll be fine.

Sorry to say, I was unabel to do any successfull lay-wire bead so far.
Simply, the filler rod was being burnt before melted and being sucked in the pool... Is there any advice how to apply lay-wire at alu?

It sounds like you're torch angle is either too vertical or too flat. With the lay wire technique, you don't dip but you also don't just lay the wire down either. You stil feed it in and maintain control of the rate of feed and you still keep it under the flame and in the gas coverage. Once you get your puddle started lay the torch back about 15 degrees so the flame bounces up and you have room to put the rod under it. That's the best I can explain it. Jody has some excellent vid's on here. Have a look at them and you'll see how do to it correctly.

[ogorir]

when you're learning lay-wire until you can really get a steady filler feed, grab the filler rod about a foot back from the end and just shove at the puddle. practice your filler feeding and eventually you won't need to do that, but it makes it easy to learn how much rod you have to push into the puddle, ect, to make lay-wire work.