beginner trouble with lap/t joint

[mrcharly]

I tried a lap/t joint at the weekend, with no success.

Tried to get the rod in tight into the corner, but kept sticking. If the rod didn't stick, a bead formed on either side of the corner, but didn't build up in between. I was using 2.5mm rods on 3mm steel.

I'm wondering if I should have tried running a bead along one piece, cleaned the slag off and added a bead joining the other piece.

When prepping the steel, I bevelled one piece of steel, only later reading that's not the way for lap or t joints. Could my problem have been a 'hollow' in the steel in the joint?

 

[GrahamGKD]

Hi Mrcharly,
Do you mean a fillet weld? I've had both of those problems in the past. Try getting the rod hot on a bit of scrap immediately prior to welding to help reduce the sticking. To help with an even deposit to both pieces watch the arc and the pool. If you see the flux running ahead of the direction of welding this will cause problems. Try angling the work down slightly to get the flux running towards the newly laid weld rather than ahead of the arc. Another trick is to start the arc at the very edge (if the work allows this) so that the first bit of flux drops over the edge (if you can follow that). Try angling the rod more acutely to the work (still evenly between the two pieces though), at least at the start of the weld. Look for an even ark between the two pieces.

I don't think laying two beads will help unless the fist bead flows to both work pieces properly. I don't think the bevelling will have helped your cause, although it shouldn't preclude being able to do the weld.

Hope this helps.

Graham.

 

[mrcharly]

Ok, will try that.

I have a need to weld flat bar to plate - the plate is vertical. Also need to join angle-iron in situ. So all vertical welds.

I'd assumed that doing it flat would be easier to start with.

Is it better to go a bit higher or lower with the current?

 

[GrahamGKD]

Yes, I'd recommend getting the feel for it in the downhand position first and then move on to the positional stuff. A higher current may help (depends on what you are on now) - if you go too high you will see undercutting at the edges of the weld and more spatter. Look for the recommendation for the rods you are using (normally on the pack). Are you using AC, DC positive or negative? Graham.

 

[mrcharly]

AC.

I tried setting the welder to the range recommended on the pack, and the current was obviously too low. The range on the welder shows a current about 10A higher than recommended for that thickness, but it seems to work - which makes me think that the welder is lying about the current output. It's a Clark, btw.

 

[Uniqueusername]

AC.

I tried setting the welder to the range recommended on the pack, and the current was obviously too low. The range on the welder shows a current about 10A higher than recommended for that thickness, but it seems to work - which makes me think that the welder is lying about the current output. It's a Clark, btw.

Completely disregarding displayed settings is pretty much par for the course on any welder let alone those from the more basic end of the spectrum.
Basically, if it feels cold then it is...................

You didn't help it by bevelling but everyone faces such joints in the real world, just crank it up a few more turns and try again.
Are you welding up or down hill ?

 

[mrcharly]

horizontal atm.

Once I've got that trick, I'll try vertical.

I did try running some beads on a vertical bit of steel - very lumpy, pooling at bottom of bead.