Internal Corner Best Practice

[Wendelspanswick]

I am curious on the best practice for doing a fillet weld with two internal corners?
With a pushing torch do you start in one corner with a negative torch angle, rotate the torch to the correct angle and push to the opposite corner.
Or do you push from the middle into the first corner and then start from the middle again into the opposite corner.

And the same question with MMA dragging a rod, start in a corner and end up pushing in the opposite corner or start in the corners and stop in the middle?

 

[J.B. Welding]

That's a very good question. I have done all the above but it's probably good practise to go out from/into the middle, especially with MMA. I would say the total length of the run is the deciding factor for me, also the application-sometimes pulling the mig an inch or so out of a corner is acceptable, IMHO.

 

[Bill Edwards]

It is a good question and, for me, there isn't a one answer fits all approach to take.

With stick, I'll perhaps be happy to let the rod go 5 degrees past vertical to push into a joint. But then, sometimes when the rod has burnt down to that point, the electrode holder gets in the way.
Again with MIG, I always push the torch but would probably be quite happy to start at 90 degrees, then go to the push angle for the run and finish.

But I think that on a critical joint where I was going to be fussy about my angles and where it needs to be right, I think I would start in the middle with the MIG to push out to each corner - probably grinding out the start before the second run.
With stick, I think it'd be a close call depending on the job. I'm not crazy about starting in a corner - you've got more metal to heat up and less margin for error, I'd prefer to finish in a corner if at all possible, but if it meant I'd need a silly rod angle I may think twice.

 

[Wendelspanswick]

Cheers for that, like you I tend to take the easy way out and do it in one hit but it's been bugging me if, on a critical joint, I ought to be doing it in two hits.

 

[Kent]

depends on the length of the run and the material. Something you might best asses with a dry run, would not want a tie in if it could be avoided inside a corner but it might have to be that way.
Just consider changing the inclination of the whole joint for better access if you can, sometimes what seems like its going to be harder is often easier

 

[roofman]

Ime no pro welder but whenever possible i like to start one end and work into the corner pushing and go right through to the other open end in one run with MIG..i find the corner looks nice and complete and with keeping the heat on i get full and regular penetration.But ime a roofer so what do i know but you did ask

 

[Richard.]

It's a question we probably all ask ourselves when faced with it but never worry about the right answer. I'm like you I usually do it in one hit and have the wrong torch/stick angle either coming in or going out for an inch or so till back on the straight. I'd imagine the correct way with mma is start in the corner and work out and pushed mig would be to do the opposite. It's one of them things where in most cases you take a practical approach over the "correct practice".

 

[Liquid Metal]

Dont want to make a habit of starting/stopping on internal or external corners..... much better to run a little towards the corner, around the corner, then away from it and along a side.
Stop/starts on corners put the stops/starts where most of the stress occurs. Especially with box section frames!!

 

[Jrstainless]

Mig it in one go
And never start on a start.
Jr