Originally Posted by
Tman1965
Don't do that!
The advice isn't good, not to say it's sh****.
It's obvious, that
singlespd neither went to welding school for the theoretical part, nor did he ever weld any aluminum alloys.
I recommend to weld some aluminum with TIG or MIG and get some hands-on experience before giving dangerous advice and talking about other's welding school.
Aluminum welds are almost always "softer" than the material before welding.
Cannondale uses 6061 for most of their frames.
I guess we should ask the OP if the guy who welded it knew how to fix bike frames and did he drill the crack on both ends to keep the material from cracking more. Did he then grind a valley along the crack for the filler rod to pool and penetrate and did the welder use the correct filler rod for the type of aluminum used in the frame? Was it heat treated? We dont know. If everything was done correctly then I dont see any reason why it cant be ground down. Its up to the OP to decide if he want to take a chance