How to fix this crack

[Mark @ Everlast]

Not trying to discourage you, but this is what I had mentioned at the outset.

 

[woodlandfarms]

Hey Mark. You gussett idea was run around a few times. Problem is it interferes with the hose connections below (or the ability to get to them. Trust me, it was heavily considered.

 

[SPYDERLK]

Just for crack repair. I've been told it forces the stresses into the hole. By theory the crack should not go past the drilled hole.

Then again, why crowd forces toward the end of a crack? I think it is a sound byte simplism. The actual issue being the heat build up during the weld helps to make the metal more mobile at the endpoint and the stresses naturally relieve better. ... Even better to also hit it with a needle scaler while cooling.

 

[RedNeckGeek]

Cracks propagate at sharp edges, like corners, and especially at the bottom and ends of cracks. If you drill a hole at the very end of the crack, you make a smooth rounded shape larger than the sharp end of the crack. It doesn't change the stress levels at that point, but because stresses aren't concentrated at the sharp crack tip, the crack doesn't propagate as easily.

Having said that, though, it makes absolutely no sense to drill the holes then obliterate them with weld metal.

Just as it makes no sense to weld over a crack. You may stop a leak for a while, but the stresses that led to the original crack are still there, as is the sharp tip of the crack, and you can be assured it will crack through the weld again.

 

[woodlandfarms]

So added some more welds and prepped for paint. Threw some JB Weld over the crack in the back.

 

[jack707]

Are you using fc or hard wire? For that repair? Asking because if I was doing the repair I would want penertration of the parent metal into the base that is deep. Either I would use stick and 7018 or duel shield 75/25.

 

[j.lwelding]

gouge/air arc the crack out, take it to a welder in town and he can use this process to take out bad weld, and actually make a groove into base metal to get more penetration. it wont crack again if done proper.

 

[rankrank1]

gouge/air arc the crack out, take it to a welder in town and he can use this process to take out bad weld, and actually make a groove into base metal to get more penetration. it wont crack again if done proper.

Could the OP have alternatively used his plasma to gouge in a do it yourself manner in lieu of an arc/air gouge which pretty much requires a gigantic welder? ( I do not have a plasma so I would have drilled holes at end of the cracks and ground a groove with my grinder just as the OP did myself. That said, it is always nice to explore the alternatives for future learning).

 

[Shield Arc]

I have used my plasma to scarf out welds. It works OK. For me it was hard to control the depth. With a carbon arc all you do is push the rod in deeper. Also a carbon arc will open up a crack, so it is more visible.

 

[j.lwelding]

Could the OP have alternatively used his plasma to gouge in a do it yourself manner in lieu of an arc/air gouge which pretty much requires a gigantic welder? ( I do not have a plasma so I would have drilled holes at end of the cracks and ground a groove with my grinder just as the OP did myself. That said, it is always nice to explore the alternatives for future learning).

yes plasma will work too but will require a gouging tip, not a cutting tip.