i would V the break out then run the bead so you can get full penetration in the joint ok you would have to ream it out
Hi guys, seeing someone mentioned us by name in an earlier post (www.gripsport
. com.au) I thought I might stick my head up and voice an opinion. Hope no one minds.
Under normal circumstances thwang's advice would be spot on, but in this case I'd suggest NOT "Vee"ing out the crack and NOT trying for a full penetration weld.
The weld at the crack itself should really only be to position the broken tube and cosmetically hold the area together. A full penetration weld would not only be a waste there (and require machining/reaming of the seat tube) but would actually create a greater heat affected zone (and hence weakness) than a quick and "cooler" weld. The actual strength of a repair like this needs to come from well designed gussets either on both sides OR wrapped around the back.
Here's a couple of photos to show what I'm on about. Two of them are actually headtube repairs (or more accurately where the headtube was about to rip off the frame), but they'll give the idea. The actual repair to all the crack shown are (by design) little more than cosmetic... the strength comes from the gusseting.
Good luck with the repair.